SyntaxFix

Programs & Examples On #Elapsedtime

SQL Server - calculate elapsed time between two datetime stamps in HH:MM:SS format

select convert(varchar, Max(Time) - Min(Time) , 108) from logTable where id=...

Can a normal Class implement multiple interfaces?

A Java class can only extend one parent class. Multiple inheritance (extends) is not allowed. Interfaces are not classes, however, and a class can implement more than one interface.

The parent interfaces are declared in a comma-separated list, after the implements keyword.

In conclusion, yes, it is possible to do:

public class A implements C,D {...}

Angular ng-click with call to a controller function not working

You should probably use the ngHref directive along with the ngClick:

 <a ng-href='#here' ng-click='go()' >click me</a>

Here is an example: http://plnkr.co/edit/FSH0tP0YBFeGwjIhKBSx?p=preview

<body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>
    {{msg}}
    <a ng-href='#here' ng-click='go()' >click me</a>
    <div style='height:1000px'>

      <a id='here'></a>

    </div>
     <h1>here</h1>
  </body>

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = 'World';

  $scope.go = function() {

    $scope.msg = 'clicked';
  }
});

I don't know if this will work with the library you are using but it will at least let you link and use the ngClick function.

** Update **

Here is a demo of the set and get working fine with a service.

http://plnkr.co/edit/FSH0tP0YBFeGwjIhKBSx?p=preview

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope, sharedProperties) {
  $scope.name = 'World';

  $scope.go = function(item) {
    sharedProperties.setListName(item);


  }

  $scope.getItem = function() {

    $scope.msg = sharedProperties.getListName();
  }
});

app.service('sharedProperties', function () {
    var list_name = '';

    return {

        getListName: function() {
            return list_name;
        },
        setListName: function(name) {
            list_name = name;
        }
    };


});

* Edit *

Please review https://github.com/centralway/lungo-angular-bridge which talks about how to use lungo and angular. Also note that if your page is completely reloading when browsing to another link, you will need to persist your shared properties into localstorage and/or a cookie.

Difference between innerText, innerHTML and value?

to add to the list, innerText will keep your text-transform, innerHTML wont

What exactly is OAuth (Open Authorization)?

Simply put OAuth is a way for applications to gain credentials to your information without directly getting your user login information to some website. For example if you write an application on your own website and want it to use data from a user's facebook account, you can use OAuth to get a token via a callback url and then use that token to make calls to the facebook API to get their use data until the token expires. Websites rely on it because it allows programmers to access their data without the user having to directly disclose their information and spread their credentials around online but still provide a level of protection to the data. Will it become the de facto method of authorization? Perhaps, it's been gaining a lot of support recently from Twitter, Facebook, and the likes where other programmers want to build applications around user data.

What is the difference between '/' and '//' when used for division?

// is floor division, it will always give you the integer floor of the result. The other is 'regular' division.

Cannot deserialize instance of object out of START_ARRAY token in Spring Webservice

Taking for granted that the JSON you posted is actually what you are seeing in the browser, then the problem is the JSON itself.

The JSON snippet you have posted is malformed.

You have posted:

[{
        "name" : "shopqwe",
        "mobiles" : [],
        "address" : {
            "town" : "city",
            "street" : "streetqwe",
            "streetNumber" : "59",
            "cordX" : 2.229997,
            "cordY" : 1.002539
        },
        "shoe"[{
                "shoeName" : "addidas",
                "number" : "631744030",
                "producent" : "nike",
                "price" : 999.0,
                "sizes" : [30.0, 35.0, 38.0]
            }]

while the correct JSON would be:

[{
        "name" : "shopqwe",
        "mobiles" : [],
        "address" : {
            "town" : "city",
            "street" : "streetqwe",
            "streetNumber" : "59",
            "cordX" : 2.229997,
            "cordY" : 1.002539
        },
        "shoe" : [{
                "shoeName" : "addidas",
                "number" : "631744030",
                "producent" : "nike",
                "price" : 999.0,
                "sizes" : [30.0, 35.0, 38.0]
            }
        ]
    }
]

How do I concatenate const/literal strings in C?

Also malloc and realloc are useful if you don't know ahead of time how many strings are being concatenated.

#include <stdio.h>
#include <string.h>

void example(const char *header, const char **words, size_t num_words)
{
    size_t message_len = strlen(header) + 1; /* + 1 for terminating NULL */
    char *message = (char*) malloc(message_len);
    strncat(message, header, message_len);

    for(int i = 0; i < num_words; ++i)
    {
       message_len += 1 + strlen(words[i]); /* 1 + for separator ';' */
       message = (char*) realloc(message, message_len);
       strncat(strncat(message, ";", message_len), words[i], message_len);
    }

    puts(message);

    free(message);
}

Export JAR with Netbeans

It does this by default, you just need to look into the project's /dist folder.

How do I ignore files in a directory in Git?

PATTERN FORMAT

  • A blank line matches no files, so it can serve as a separator for readability.

  • A line starting with # serves as a comment.

  • An optional prefix ! which negates the pattern; any matching file excluded by a previous pattern will become included again. If a negated pattern matches, this will override lower precedence patterns sources.

  • If the pattern ends with a slash, it is removed for the purpose of the following description, but it would only find a match with a directory. In other words, foo/ will match a directory foo and paths underneath it, but will not match a regular file or a symbolic link foo (this is consistent with the way how pathspec works in general in git).

  • If the pattern does not contain a slash /, git treats it as a shell glob pattern and checks for a match against the pathname relative to the location of the .gitignore file (relative to the toplevel of the work tree if not from a .gitignore file).

  • Otherwise, git treats the pattern as a shell glob suitable for consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in the pattern will not match a / in the pathname. For example, Documentation/*.html matches Documentation/git.html but not Documentation/ppc/ppc.html or tools/perf/Documentation/perf.html.

  • A leading slash matches the beginning of the pathname. For example, /*.c matches cat-file.c but not mozilla-sha1/sha1.c.

You can find more here

git help gitignore
or
man gitignore

Setting the character encoding in form submit for Internet Explorer

I've got the same problem here. I have an UTF-8 Page an need to post to an ISO-8859-1 server.

Looks like IE can't handle ISO-8859-1. But it can handle ISO-8859-15.

<form accept-charset="ISO-8859-15">
  ...
</form>

So this worked for me, since ISO-8859-1 and ISO-8859-15 are almost the same.

Can I hide/show asp:Menu items based on role?

To find menu items in content page base on roles

 protected void Page_Load(object sender, EventArgs e)
{
   if (Session["AdminSuccess"] != null)
        {
           Menu mainMenu = (Menu)Page.Master.FindControl("NavigationMenu");

    //you must know the index of items to be removed first
    mainMenu.Items.RemoveAt(1);

    //or you try to hide menu and list items inside menu with css 
    // cssclass must be defined in style tag in .aspx page
    mainMenu.CssClass = ".hide";

        }   

}

<style type="text/css">
.hide
    {
        visibility: hidden;
     }
  </style>

Current time formatting with Javascript

2.39KB minified. One file. https://github.com/rhroyston/clock-js

Current Time is

var str = clock.month;
var m = str.charAt(0).toUpperCase() + str.slice(1,3); //gets you abbreviated month
clock.weekday + ' ' + clock.time + ' ' + clock.day + ' ' + m + ' ' + clock.year; //"tuesday 5:50 PM 3 May 2016"

MySQL INNER JOIN select only one row from second table

 
SELECT U.*, V.* FROM users AS U 
INNER JOIN (SELECT *
FROM payments
WHERE id IN (
SELECT MAX(id)
FROM payments
GROUP BY user_id
)) AS V ON U.id = V.user_id

This will get it working

How can I undo a mysql statement that I just executed?

You can only do so during a transaction.

BEGIN;
INSERT INTO xxx ...;
DELETE FROM ...;

Then you can either:

COMMIT; -- will confirm your changes

Or

ROLLBACK -- will undo your previous changes

How to find length of a string array?

 
String car [];

is a reference to an array of String-s. You can't see a length because there is no array there!

Given a URL to a text file, what is the simplest way to read the contents of the text file?

 
import urllib2
for line in urllib2.urlopen("http://www.myhost.com/SomeFile.txt"):
    print line

How do I connect to this localhost from another computer on the same network?

Provided both machines are in the same workgroup, open cmd.exe on the machine you want to connect to, type ipconfig and note the IP at the IPv4 Address line.

Then, on the machine you want to connect with, use http:// + the IP of the target machine.

That should do it.

Return a `struct` from a function in C

 
struct emp {
    int id;
    char *name;
};

struct emp get() {
    char *name = "John";

    struct emp e1 = {100, name};

    return (e1);
}

int main() {

    struct emp e2 = get();

    printf("%s\n", e2.name);
}

works fine with newer versions of compilers. Just like id, content of the name gets copied to the assigned structure variable.

Deleting all files from a folder using PHP?

 
$files = glob('path/to/temp/*'); // get all file names
foreach($files as $file){ // iterate files
  if(is_file($file)) {
    unlink($file); // delete file
  }
}

If you want to remove 'hidden' files like .htaccess, you have to use

$files = glob('path/to/temp/{,.}*', GLOB_BRACE);

How can I tell how many objects I've stored in an S3 bucket?

Here's the boto3 version of the python script embedded above.

import sys
import boto3

s3 = boto3.resource('s3')
s3bucket = s3.Bucket(sys.argv[1])
size = 0
totalCount = 0

for key in s3bucket.objects.all():
    totalCount += 1
    size += key.size

print('total size:')
print("%.3f GB" % (size*1.0/1024/1024/1024))
print('total count:')
print(totalCount)`

How to code a BAT file to always run as admin mode?

 
go get github.com/mattn/sudo

Then

sudo Example1Server.exe

Count table rows

You have to use count() returns the number of rows that matches a specified criteria 

select count(*) from table_name;

Do you (really) write exception safe code?

Your question makes an assertion, that "Writing exception-safe code is very hard". I will answer your questions first, and then, answer the hidden question behind them.

Answering questions

Do you really write exception safe code?

Of course, I do.

This is the reason Java lost a lot of its appeal to me as a C++ programmer (lack of RAII semantics), but I am digressing: This is a C++ question.

It is, in fact, necessary when you need to work with STL or Boost code. For example, C++ threads (boost::thread or std::thread) will throw an exception to exit gracefully.

Are you sure your last "production ready" code is exception safe?

Can you even be sure, that it is?

Writing exception-safe code is like writing bug-free code.

You can't be 100% sure your code is exception safe. But then, you strive for it, using well-known patterns, and avoiding well-known anti-patterns.

Do you know and/or actually use alternatives that work?

There are no viable alternatives in C++ (i.e. you'll need to revert back to C and avoid C++ libraries, as well as external surprises like Windows SEH).

Writing exception safe code

To write exception safe code, you must know first what level of exception safety each instruction you write is.

For example, a new can throw an exception, but assigning a built-in (e.g. an int, or a pointer) won't fail. A swap will never fail (don't ever write a throwing swap), a std::list::push_back can throw...

Exception guarantee

The first thing to understand is that you must be able to evaluate the exception guarantee offered by all of your functions:

  1. none: Your code should never offer that. This code will leak everything, and break down at the very first exception thrown.
  2. basic: This is the guarantee you must at the very least offer, that is, if an exception is thrown, no resources are leaked, and all objects are still whole
  3. strong: The processing will either succeed, or throw an exception, but if it throws, then the data will be in the same state as if the processing had not started at all (this gives a transactional power to C++)
  4. nothrow/nofail: The processing will succeed.

Example of code

The following code seems like correct C++, but in truth, offers the "none" guarantee, and thus, it is not correct:

void doSomething(T & t)
{
   if(std::numeric_limits<int>::max() > t.integer)  // 1.   nothrow/nofail
      t.integer += 1 ;                              // 1'.  nothrow/nofail
   X * x = new X() ;                // 2. basic : can throw with new and X constructor
   t.list.push_back(x) ;            // 3. strong : can throw
   x->doSomethingThatCanThrow() ;   // 4. basic : can throw
}

I write all my code with this kind of analysis in mind.

The lowest guarantee offered is basic, but then, the ordering of each instruction makes the whole function "none", because if 3. throws, x will leak.

The first thing to do would be to make the function "basic", that is putting x in a smart pointer until it is safely owned by the list:

void doSomething(T & t)
{
   if(std::numeric_limits<int>::max() > t.integer)  // 1.   nothrow/nofail
      t.integer += 1 ;                              // 1'.  nothrow/nofail
   std::auto_ptr<X> x(new X()) ;    // 2.  basic : can throw with new and X constructor
   X * px = x.get() ;               // 2'. nothrow/nofail
   t.list.push_back(px) ;           // 3.  strong : can throw
   x.release() ;                    // 3'. nothrow/nofail
   px->doSomethingThatCanThrow() ;  // 4.  basic : can throw
}

Now, our code offers a "basic" guarantee. Nothing will leak, and all objects will be in a correct state. But we could offer more, that is, the strong guarantee. This is where it can become costly, and this is why not all C++ code is strong. Let's try it:

void doSomething(T & t)
{
   // we create "x"
   std::auto_ptr<X> x(new X()) ;    // 1. basic : can throw with new and X constructor
   X * px = x.get() ;               // 2. nothrow/nofail
   px->doSomethingThatCanThrow() ;  // 3. basic : can throw

   // we copy the original container to avoid changing it
   T t2(t) ;                        // 4. strong : can throw with T copy-constructor

   // we put "x" in the copied container
   t2.list.push_back(px) ;          // 5. strong : can throw
   x.release() ;                    // 6. nothrow/nofail
   if(std::numeric_limits<int>::max() > t2.integer)  // 7.   nothrow/nofail
      t2.integer += 1 ;                              // 7'.  nothrow/nofail

   // we swap both containers
   t.swap(t2) ;                     // 8. nothrow/nofail
}

We re-ordered the operations, first creating and setting X to its right value. If any operation fails, then t is not modified, so, operation 1 to 3 can be considered "strong": If something throws, t is not modified, and X will not leak because it's owned by the smart pointer.

Then, we create a copy t2 of t, and work on this copy from operation 4 to 7. If something throws, t2 is modified, but then, t is still the original. We still offer the strong guarantee.

Then, we swap t and t2. Swap operations should be nothrow in C++, so let's hope the swap you wrote for T is nothrow (if it isn't, rewrite it so it is nothrow).

So, if we reach the end of the function, everything succeeded (No need of a return type) and t has its excepted value. If it fails, then t has still its original value.

Now, offering the strong guarantee could be quite costly, so don't strive to offer the strong guarantee to all your code, but if you can do it without a cost (and C++ inlining and other optimization could make all the code above costless), then do it. The function user will thank you for it.

Conclusion

It takes some habit to write exception-safe code. You'll need to evaluate the guarantee offered by each instruction you'll use, and then, you'll need to evaluate the guarantee offered by a list of instructions.

Of course, the C++ compiler won't back up the guarantee (in my code, I offer the guarantee as a @warning doxygen tag), which is kinda sad, but it should not stop you from trying to write exception-safe code.

Normal failure vs. bug

How can a programmer guarantee that a no-fail function will always succeed? After all, the function could have a bug.

This is true. The exception guarantees are supposed to be offered by bug-free code. But then, in any language, calling a function supposes the function is bug-free. No sane code protects itself against the possibility of it having a bug. Write code the best you can, and then, offer the guarantee with the supposition it is bug-free. And if there is a bug, correct it.

Exceptions are for exceptional processing failure, not for code bugs.

Last words

Now, the question is "Is this worth it ?".

Of course, it is. Having a "nothrow/no-fail" function knowing that the function won't fail is a great boon. The same can be said for a "strong" function, which enables you to write code with transactional semantics, like databases, with commit/rollback features, the commit being the normal execution of the code, throwing exceptions being the rollback.

Then, the "basic" is the very least guarantee you should offer. C++ is a very strong language there, with its scopes, enabling you to avoid any resource leaks (something a garbage collector would find it difficult to offer for the database, connection or file handles).

So, as far as I see it, it is worth it.

Edit 2010-01-29: About non-throwing swap

nobar made a comment that I believe, is quite relevant, because it is part of "how do you write exception safe code":

  • [me] A swap will never fail (don't even write a throwing swap)
  • [nobar] This is a good recommendation for custom-written swap() functions. It should be noted, however, that std::swap() can fail based on the operations that it uses internally

the default std::swap will make copies and assignments, which, for some objects, can throw. Thus, the default swap could throw, either used for your classes or even for STL classes. As far as the C++ standard is concerned, the swap operation for vector, deque, and list won't throw, whereas it could for map if the comparison functor can throw on copy construction (See The C++ Programming Language, Special Edition, appendix E, E.4.3.Swap).

Looking at Visual C++ 2008 implementation of the vector's swap, the vector's swap won't throw if the two vectors have the same allocator (i.e., the normal case), but will make copies if they have different allocators. And thus, I assume it could throw in this last case.

So, the original text still holds: Don't ever write a throwing swap, but nobar's comment must be remembered: Be sure the objects you're swapping have a non-throwing swap.

Edit 2011-11-06: Interesting article

Dave Abrahams, who gave us the basic/strong/nothrow guarantees, described in an article his experience about making the STL exception safe:

http://www.boost.org/community/exception_safety.html

Look at the 7th point (Automated testing for exception-safety), where he relies on automated unit testing to make sure every case is tested. I guess this part is an excellent answer to the question author's "Can you even be sure, that it is?".

Edit 2013-05-31: Comment from dionadar

t.integer += 1; is without the guarantee that overflow will not happen NOT exception safe, and in fact may technically invoke UB! (Signed overflow is UB: C++11 5/4 "If during the evaluation of an expression, the result is not mathematically defined or not in the range of representable values for its type, the behavior is undefined.") Note that unsigned integer do not overflow, but do their computations in an equivalence class modulo 2^#bits.

Dionadar is referring to the following line, which indeed has undefined behaviour.

   t.integer += 1 ;                 // 1. nothrow/nofail

The solution here is to verify if the integer is already at its max value (using std::numeric_limits<T>::max()) before doing the addition.

My error would go in the "Normal failure vs. bug" section, that is, a bug. It doesn't invalidate the reasoning, and it does not mean the exception-safe code is useless because impossible to attain. You can't protect yourself against the computer switching off, or compiler bugs, or even your bugs, or other errors. You can't attain perfection, but you can try to get as near as possible.

I corrected the code with Dionadar's comment in mind.

T-SQL to list all the user mappings with database roles/permissions for a Login

 
CREATE TABLE #tempww (

    LoginName nvarchar(max),
    DBname nvarchar(max),
    Username nvarchar(max), 
    AliasName nvarchar(max)
)

INSERT INTO #tempww 

EXEC master..sp_msloginmappings 

-- display results

declare @col varchar(1000)

declare @sql varchar(2000)

select @col = COALESCE(@col + ', ','') + QUOTENAME(DBname)

from #tempww Group by DBname

Set @sql='select * from (select LoginName,Username,AliasName,DBname,row_number() over(order by (select 0)) rn from #tempww) src

PIVOT (Max(rn) FOR DBname

IN ('+@col+')) pvt'

EXEC(@sql)



-- cleanup
DROP TABLE #tempww

File 'app/hero.ts' is not a module error in the console, where to store interfaces files in directory structure with angular2?

In my case I had forgotten to save changes to the file 'app/hero.ts', after saving and restarting ng serve the issue was resolved.

How to use tick / checkmark symbol (?) instead of bullets in unordered list?

As an addition to the solution:

ul li:before {
 content: '?'; 
}

You can use any SVG icon as the content, such as the Font Aswesome.

enter image description here

_x000D_
_x000D_ 
ul {_x000D_
  list-style: none;_x000D_
  padding-left: 0;_x000D_
}_x000D_
li {_x000D_
  position: relative;_x000D_
  padding-left: 1.5em;  /* space to preserve indentation on wrap */_x000D_
}_x000D_
li:before {_x000D_
  content: '';  /* placeholder for the SVG */_x000D_
  position: absolute;_x000D_
  left: 0;  /* place the SVG at the start of the padding */_x000D_
  width: 1em;_x000D_
  height: 1em;_x000D_
  background: url("data:image/svg+xml;utf8,<?xml version='1.0' encoding='utf-8'?><svg width='18' height='18' viewBox='0 0 1792 1792' xmlns='http://www.w3.org/2000/svg'><path d='M1671 566q0 40-28 68l-724 724-136 136q-28 28-68 28t-68-28l-136-136-362-362q-28-28-28-68t28-68l136-136q28-28 68-28t68 28l294 295 656-657q28-28 68-28t68 28l136 136q28 28 28 68z'/></svg>") no-repeat;_x000D_
}
_x000D_ 
<ul>_x000D_
  <li>this is my text</li>_x000D_
  <li>this is my text</li>_x000D_
  <li>This is my text, it's pretty long so it needs to wrap. Note that wrapping preserves the indentation that bullets had!</li>_x000D_
  <li>this is my text</li>_x000D_
  <li>this is my text</li>_x000D_
</ul>
_x000D_
_x000D_
_x000D_

Note: To solve the wrapping problem that other answers had:

  • we reserve 1.5m ems of space at the left of each <li>
  • then position the SVG at the start of that space (position: absolute; left: 0)

Here are more Font Awesome black icons.

Check this CODEPEN to see how you can add colors and change their size.

Bootstrap 4 - Glyphicons migration?

It is not shipped with bootstrap 4 yet, but now Bootstrap team is developing their icon library.

https://icons.getbootstrap.com/

https://github.com/twbs/icons

How to get HTTP Response Code using Selenium WebDriver

You can use BrowserMob proxy to capture the requests and responses with a HttpRequestInterceptor. Here is an example in Java:

// Start the BrowserMob proxy
ProxyServer server = new ProxyServer(9978);
server.start();

server.addResponseInterceptor(new HttpResponseInterceptor()
{
    @Override
    public void process(HttpResponse response, HttpContext context)
        throws HttpException, IOException
    {
        System.out.println(response.getStatusLine());
    }
});

// Get selenium proxy
Proxy proxy = server.seleniumProxy();

// Configure desired capability for using proxy server with WebDriver
DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(CapabilityType.PROXY, proxy);

// Set up driver
WebDriver driver = new FirefoxDriver(capabilities);

driver.get("http://stackoverflow.com/questions/6509628/webdriver-get-http-response-code");

// Close the browser
driver.quit();

anaconda - graphviz - can't import after installation

Graphviz is evidently included in Anaconda so as to be used with pydot or pydot-ng (both of which are included in Anaconda). You may want to consider using one of those instead of the 'graphviz' Python module.

How do I ignore ampersands in a SQL script running from SQL Plus?

You can set the special character, which is looked for upon execution of a script, to another value by means of using the SET DEFINE <1_CHARACTER>

By default, the DEFINE function itself is on, and it is set to &

It can be turned off - as mentioned already - but it can be avoided as well by means of setting it to a different value. Be very aware of what sign you set it to. In the below example, I've chose the # character, but that choice is just an example.

SQL> select '&var_ampersand #var_hash' from dual;
Enter value for var_ampersand: a value

'AVALUE#VAR_HASH'
-----------------
a value #var_hash

SQL> set define #
SQL> r
  1* select '&var_ampersand #var_hash' from dual
Enter value for var_hash: another value

'&VAR_AMPERSANDANOTHERVALUE'
----------------------------
&var_ampersand another value

SQL>

NPM Install Error:Unexpected end of JSON input while parsing near '...nt-webpack-plugin":"0'

delete npm and npm-cache folders in C:\Users\admin\AppData\Roaming\ (windows) then execute cmd

npm cache clear --force

npm cache verify

update npm to latest version

npm i -g npm

then create your project 1)Angular

npm i -g @angular/cli@latest

ng new HelloWorld

2)React

npm i -g create-react-app

create-react-app react-app

How to create enum like type in TypeScript?

As of TypeScript 0.9 (currently an alpha release) you can use the enum definition like this:

enum TShirtSize {
  Small,
  Medium,
  Large
}

var mySize = TShirtSize.Large;

By default, these enumerations will be assigned 0, 1 and 2 respectively. If you want to explicitly set these numbers, you can do so as part of the enum declaration.

Listing 6.2 Enumerations with explicit members

enum TShirtSize {
  Small = 3,
  Medium = 5,
  Large = 8
}

var mySize = TShirtSize.Large;

Both of these examples lifted directly out of TypeScript for JavaScript Programmers.

Note that this is different to the 0.8 specification. The 0.8 specification looked like this - but it was marked as experimental and likely to change, so you'll have to update any old code:

Disclaimer - this 0.8 example would be broken in newer versions of the TypeScript compiler.

enum TShirtSize {
  Small: 3,
  Medium: 5,
  Large: 8
}

var mySize = TShirtSize.Large;

Visual Studio C# IntelliSense not automatically displaying

I simply closed all pages of visual studio and reopened ..it worked.

Python: how to print range a-z?

Hints:

import string
print string.ascii_lowercase

and 

for i in xrange(0, 10, 2):
    print i

and

"hello{0}, world!".format('z')

Read next word in java

Using Scanners, you will end up spawning a lot of objects for every line. You will generate a decent amount of garbage for the GC with large files. Also, it is nearly three times slower than using split().

On the other hand, If you split by space (line.split(" ")), the code will fail if you try to read a file with a different whitespace delimiter. If split() expects you to write a regular expression, and it does matching anyway, use split("\\s") instead, that matches a "bit" more whitespace than just a space character.

P.S.: Sorry, I don't have right to comment on already given answers.

How do I add multiple "NOT LIKE '%?%' in the WHERE clause of sqlite3?

I'm not sure why you're avoiding the AND clause. It is the simplest solution.

Otherwise, you would need to do an INTERSECT of multiple queries:

SELECT word FROM table WHERE word NOT LIKE '%a%'
INTERSECT
SELECT word FROM table WHERE word NOT LIKE '%b%'
INTERSECT
SELECT word FROM table WHERE word NOT LIKE '%c%';

Alternatively, you can use a regular expression if your version of SQL supports it.

How to create a new variable in a data.frame based on a condition?

If you have a very limited number of levels, you could try converting y into factor and change its levels.

> xy <- data.frame(x = c(1, 2, 4), y = c(1, 4, 5))
> xy$w <- as.factor(xy$y)
> levels(xy$w) <- c("good", "fair", "bad")
> xy
  x y    w
1 1 1 good
2 2 4 fair
3 4 5  bad

How do I prevent Conda from activating the base environment by default?

So in the end I found that if I commented out the Conda initialisation block like so:

# >>> conda initialize >>>
# !! Contents within this block are managed by 'conda init' !!
# __conda_setup="$('/Users/geoff/anaconda2/bin/conda' 'shell.bash' 'hook' 2> /dev/null)"
# if [ $? -eq 0 ]; then
    # eval "$__conda_setup"
# else
if [ -f "/Users/geoff/anaconda2/etc/profile.d/conda.sh" ]; then
    . "/Users/geoff/anaconda2/etc/profile.d/conda.sh"
else
    export PATH="/Users/geoff/anaconda2/bin:$PATH"
fi
# fi
# unset __conda_setup
# <<< conda initialize <<<

It works exactly how I want. That is, Conda is available to activate an environment if I want, but doesn't activate by default.

How to convert local time string to UTC?

Thanks @rofly, the full conversion from string to string is as follows:

time.strftime("%Y-%m-%d %H:%M:%S", 
              time.gmtime(time.mktime(time.strptime("2008-09-17 14:04:00", 
                                                    "%Y-%m-%d %H:%M:%S"))))

My summary of the time/calendar functions:

time.strptime
string --> tuple (no timezone applied, so matches string)

time.mktime
local time tuple --> seconds since epoch (always local time)

time.gmtime
seconds since epoch --> tuple in UTC

and

calendar.timegm
tuple in UTC --> seconds since epoch

time.localtime
seconds since epoch --> tuple in local timezone

R legend placement in a plot

You have to add the size of the legend box to the ylim range

#Plot an empty graph and legend to get the size of the legend
x <-1:10
y <-11:20
plot(x,y,type="n", xaxt="n", yaxt="n")
my.legend.size <-legend("topright",c("Series1","Series2","Series3"),plot = FALSE)

#custom ylim. Add the height of legend to upper bound of the range
my.range <- range(y)
my.range[2] <- 1.04*(my.range[2]+my.legend.size$rect$h)

#draw the plot with custom ylim
plot(x,y,ylim=my.range, type="l")
my.legend.size <-legend("topright",c("Series1","Series2","Series3"))

enter image description here

Add php variable inside echo statement as href link address?

This worked much better in my case.

HTML in PHP: <a href=".$link_address.">Link</a>

Limit to 2 decimal places with a simple pipe

It's Works

.ts -> pi = 3.1415

.html -> {{ pi | number : '1.0-2' }}

Ouput -> 3.14
  1. if it has a decimal it only shows one
  2. if it has two decimals it shows both

https://stackblitz.com/edit/angular-e8g2pt?file=src/app/app.component.html

this works for me!!! thanks!!

Detect if range is empty

 
Dim cel As Range, hasNoData As Boolean

    hasNoData = True
    For Each cel In Selection
        hasNoData = hasNoData And IsEmpty(cel)
    Next

This will return True if no cells in Selection contains any data. For a specific range, just substitute RANGE(...) for Selection.

Android Studio doesn't start, fails saying components not installed

I have a proxy in my connection (university connection) and I solved the problem by using the SDK manager to download the SDK packages then I opened android studio and it worked seamlessly.

Show how many characters remaining in a HTML text box using JavaScript

HTML:

 <form>
  <textarea id='text' maxlength='10'></textarea>
  <div id='msg'>10 characters left</div>
  <div id='lastChar'></div>
</form>

JS:

function charCount() {
  var textEntered = document.getElementById('text').value;
  var msg = document.getElementById('msg');
  var counter = (10-(textEntered.length));
  msg.textContent = counter+' characters left';
}

var el = document.getElementById('text');
el.addEventListener('keyup',charCount,false);

How do I escape only single quotes?

After a long time fighting with this problem, I think I have found a better solution.

The combination of two functions makes it possible to escape a string to use as HTML.

One, to escape double quote if you use the string inside a JavaScript function call; and a second one to escape the single quote, avoiding those simple quotes that go around the argument.

Solution:

mysql_real_escape_string(htmlspecialchars($string))

Solve:

  • a PHP line created to call a JavaScript function like

echo 'onclick="javascript_function(\'' . mysql_real_escape_string(htmlspecialchars($string))"

How to drop all user tables?

If you just want a really simple way to do this.. Heres a script I have used in the past

select 'drop table '||table_name||' cascade constraints;' from user_tables;

This will print out a series of drop commands for all tables in the schema. Spool the result of this query and execute it.

Source: https://forums.oracle.com/forums/thread.jspa?threadID=614090

Likewise if you want to clear more than tables you can edit the following to suit your needs

select 'drop '||object_type||' '|| object_name || ';' from user_objects where object_type in ('VIEW','PACKAGE','SEQUENCE', 'PROCEDURE', 'FUNCTION', 'INDEX')

Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Collections.Generic.IList'

Try this -->

 new DzieckoAndOpiekun(
                         p.Imie,
                         p.Nazwisko,
                         p.Opiekun.Imie,
                         p.Opiekun.Nazwisko).ToList()

How can I use pickle to save a dict?

Simple way to dump a Python data (e.g. dictionary) to a pickle file.

import pickle

your_dictionary = {}

pickle.dump(your_dictionary, open('pickle_file_name.p', 'wb'))

Which Ruby version am I really running?

Run this command:

rvm get stable --auto-dotfiles

and make sure to read all the output. RVM will tell you if something is wrong, which in your case might be because GEM_HOME is set to something different then PATH.

How can I sort a dictionary by key?

Found another way:

import json
print json.dumps(d, sort_keys = True)

upd:
1. this also sorts nested objects (thanks @DanielF).
2. python dictionaries are unordered therefore this is sutable for print or assign to str only.

array of string with unknown size

string foo = "Apple, Plum, Cherry";

string[] myArr = null;

myArr = foo.Split(',');

NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equalsIgnoreCase(java.lang.String)' on a null object reference

This is the error line:

if (called_from.equalsIgnoreCase("add")) {  --->38th error line

This means that called_from is null. Simple check if it is null above:

String called_from = getIntent().getStringExtra("called");

if(called_from == null) {
    called_from = "empty string";
}
if (called_from.equalsIgnoreCase("add")) {
    // do whatever
} else {
    // do whatever
}

That way, if called_from is null, it'll execute the else part of your if statement.

Are these methods thread safe?

It follows the convention that static methods should be thread-safe, but actually in v2 that static api is a proxy to an instance method on a default instance: in the case protobuf-net, it internally minimises contention points, and synchronises the internal state when necessary. Basically the library goes out of its way to do things right so that you can have simple code.

Gradle proxy configuration

Try the following:

gradle -Dhttp.proxyHost=yourProxy -Dhttp.proxyPort=yourPort -Dhttp.proxyUser=usernameProxy -Dhttp.proxyPassword=yourPassoword

Format / Suppress Scientific Notation from Python Pandas Aggregation Results

Setting a fixed number of decimal places globally is often a bad idea since it is unlikely that it will be an appropriate number of decimal places for all of your various data that you will display regardless of magnitude. Instead, try this which will give you scientific notation only for large and very small values (and adds a thousands separator unless you omit the ","):

pd.set_option('display.float_format', lambda x: '%,g' % x)

Or to almost completely suppress scientific notation without losing precision, try this:

pd.set_option('display.float_format', str)

how to implement a long click listener on a listview

I think this above code will work on LongClicking the listview, not the individual items.

why not use registerForContextMenu(listView). and then get the callback in OnCreateContextMenu.

For most use cases this will work same.

What does print(... sep='', '\t' ) mean?

sep='' in the context of a function call sets the named argument sep to an empty string. See the print() function; sep is the separator used between multiple values when printing. The default is a space (sep=' '), this function call makes sure that there is no space between Property tax: $ and the formatted tax floating point value.

Compare the output of the following three print() calls to see the difference

>>> print('foo', 'bar')
foo bar
>>> print('foo', 'bar', sep='')
foobar
>>> print('foo', 'bar', sep=' -> ')
foo -> bar

All that changed is the sep argument value.

\t in a string literal is an escape sequence for tab character, horizontal whitespace, ASCII codepoint 9.

\t is easier to read and type than the actual tab character. See the table of recognized escape sequences for string literals.

Using a space or a \t tab as a print separator shows the difference:

>>> print('eggs', 'ham')
eggs ham
>>> print('eggs', 'ham', sep='\t')
eggs    ham

How to run a function in jquery

Alternatively (I'd say preferably), you can do it like this:

$(function () {
  $("div.class, div.secondclass").click(function(){
    //Doo something
  });
});

Import Error: No module named numpy

You should try to install numpy using one of those:

pip install numpy
pip2 install numpy
pip3 install numpy

For some reason in my case pip2 solved the problem

keytool error bash: keytool: command not found

These are the steps which solved my problem:

  • Search the path where my java was installed 

    find / -name jre

  • Move to java directory (where jre was installed on my server)

    cd /path/to/jre/bin

  • Create SSL certificate with keytool command

    ./keytool -genkey -alias [mypassword] -keyalg [RSA]

bower command not found

I am using node version manager. I was getting this error message because I had switched to a different version of node. When I switched back to the version of node where I installed bower, this error went away. In my case, the command was nvm use stable

Phone: numeric keyboard for text input

 
 <input type="text" inputmode="decimal">

it will give u text input using numeric key-pad

How do I add a border to an image in HTML?

Here is some HTML and CSS code that would solve your issue:

CSS

.ImageBorder
{
    border-width: 1px;
    border-color: Black;
}

HTML

<img src="MyImage.gif" class="ImageBorder" />

How to use JavaScript with Selenium WebDriver Java

If you want to read text of any element using javascript executor, you can do something like following code:

WebElement ele = driver.findElement(By.xpath("//div[@class='infaCompositeViewTitle']"));
String assets = (String) js.executeScript("return arguments[0].getElementsByTagName('span')[1].textContent;", ele);

In this example, I have following HTML fragment and I am reading "156".

<div class="infaCompositeViewTitle">
   <span>All Assets</span>
   <span>156</span>
</div>

If using maven, usually you put log4j.properties under java or resources?

Some "data mining" accounts for that src/main/resources is the typical place.

Results on Google Code Search:

  • src/main/resources/log4j.properties: 4877
  • src/main/java/log4j.properties: 215

Global variables in Javascript across multiple files

OK, guys, here's my little test too. I had a similar problem, so I decided to test out 3 situations:

  1. One HTML file, one external JS file... does it work at all - can functions communicate via a global var?
  2. Two HTML files, one external JS file, one browser, two tabs: will they interfere via the global var?
  3. One HTML file, open by 2 browsers, will it work and will they interfere?

All the results were as expected.

  1. It works. Functions f1() and f2() communicate via global var (var is in the external JS file, not in HTML file).
  2. They do not interfere. Apparently distinct copies of JS file have been made for each browser tab, each HTML page.
  3. All works independently, as expected.

Instead of browsing tutorials, I found it easier to try it out, so I did. My conclusion: whenever you include an external JS file in your HTML page, the contents of the external JS gets "copy/pasted" into your HTML page before the page is rendered. Or into your PHP page if you will. Please correct me if I'm wrong here. Thanx.

My example files follow:

EXTERNAL JS:

var global = 0;

function f1()
{
    alert('fired: f1');
    global = 1;
    alert('global changed to 1');
}

function f2()
{
    alert('fired f2');
    alert('value of global: '+global);
}

HTML 1:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript" src="external.js"></script>
<title>External JS Globals - index.php</title>
</head>
<body>
<button type="button" id="button1" onclick="f1();"> fire f1 </button>
<br />
<button type="button" id="button2" onclick="f2();"> fire f2 </button>
<br />
</body>
</html>

HTML 2

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript" src="external.js"></script>
<title>External JS Globals - index2.php</title>
</head>
<body>
<button type="button" id="button1" onclick="f1();"> fire f1 </button>
<br />
<button type="button" id="button2" onclick="f2();"> fire f2 </button>
<br />
</body>
</html>

SVN Repository on Google Drive or DropBox

While possible, it's potentially very risky - if you attempt to commit changes to the repository from 2 different locations simultaneously, you'll get a giant mess due to the file conflicts. Get a free private SVN host somewhere, or set up a repository on a server you have access to.

Edit based on a recent experience: If you have files open that are managed by Dropbox and your computer crashes, your files may be truncated to 0 bytes. If this happens to the files which manage your repository, your repository will be corrupted. If you discover this soon enough, you can use Dropbox's "recover old version" feature but you're still taking a risk.

Remove border from IFrame

To remove border you can use CSS border property to none.

<iframe src="myURL" width="300" height="300" style="border: none">Browser not compatible.</iframe>

How to center form in bootstrap 3

use centered class with offset-6 like below sample.

<body class="container">
<div class="col-lg-1 col-offset-6 centered">
    <img data-src="holder.js/100x100" alt="" />
</div>

Specify the from user when sending email using the mail command

mail -r [email protected] -R [email protected]

-r = from-addr -R = reply-to addr

The author has indicated his version of mail doesn't support this flag. But if you have a version that does this works fine.

Is there a way to get the XPath in Google Chrome?

As of the latest update for chrome you can now click any element in the element inspector and copy the XPath to clipboard.

Integrity constraint violation: 1452 Cannot add or update a child row:

Make sure you have project_id in the fillable property of your Comment model.

I had the same issue, And this was the reason.

RequestDispatcher.forward() vs HttpServletResponse.sendRedirect()

In the web development world, the term "redirect" is the act of sending the client an empty HTTP response with just a Location header containing the new URL to which the client has to send a brand new GET request. So basically:

  • Client sends a HTTP request to some.jsp.
  • Server sends a HTTP response back with Location: other.jsp header
  • Client sends a HTTP request to other.jsp (this get reflected in browser address bar!)
  • Server sends a HTTP response back with content of other.jsp.

You can track it with the web browser's builtin/addon developer toolset. Press F12 in Chrome/IE9/Firebug and check the "Network" section to see it.

Exactly the above is achieved by sendRedirect("other.jsp"). The RequestDispatcher#forward() doesn't send a redirect. Instead, it uses the content of the target page as HTTP response.

  • Client sends a HTTP request to some.jsp.
  • Server sends a HTTP response back with content of other.jsp.

However, as the original HTTP request was to some.jsp, the URL in browser address bar remains unchanged. Also, any request attributes set in the controller behind some.jsp will be available in other.jsp. This does not happen during a redirect because you're basically forcing the client to create a new HTTP request on other.jsp, hereby throwing away the original request on some.jsp including all of its attribtues.

The RequestDispatcher is extremely useful in the MVC paradigm and/or when you want to hide JSP's from direct access. You can put JSP's in the /WEB-INF folder and use a Servlet which controls, preprocesses and postprocesses the requests. The JSPs in the /WEB-INF folder are not directly accessible by URL, but the Servlet can access them using RequestDispatcher#forward().

You can for example have a JSP file in /WEB-INF/login.jsp and a LoginServlet which is mapped on an url-pattern of /login. When you invoke http://example.com/context/login, then the servlet's doGet() will be invoked. You can do any preprocessing stuff in there and finally forward the request like:

request.getRequestDispatcher("/WEB-INF/login.jsp").forward(request, response);

When you submit a form, you normally want to use POST:

<form action="login" method="post">

This way the servlet's doPost() will be invoked and you can do any postprocessing stuff in there (e.g. validation, business logic, login the user, etc).

If there are any errors, then you normally want to forward the request back to the same page and display the errors there next to the input fields and so on. You can use the RequestDispatcher for this.

If a POST is successful, you normally want to redirect the request, so that the request won't be resubmitted when the user refreshes the request (e.g. pressing F5 or navigating back in history).

User user = userDAO.find(username, password);
if (user != null) {
    request.getSession().setAttribute("user", user); // Login user.
    response.sendRedirect("home"); // Redirects to http://example.com/context/home after succesful login.
} else {
    request.setAttribute("error", "Unknown login, please try again."); // Set error.
    request.getRequestDispatcher("/WEB-INF/login.jsp").forward(request, response); // Forward to same page so that you can display error.
}

A redirect thus instructs the client to fire a new GET request on the given URL. Refreshing the request would then only refresh the redirected request and not the initial request. This will avoid "double submits" and confusion and bad user experiences. This is also called the POST-Redirect-GET pattern.

See also:

Amazon S3 and Cloudfront cache, how to clear cache or synchronize their cache

(edit: Does not work)As of 2014, You can clear your cache whenever you want, Please go thorough the Documentation or just go to your distribution settings>Behaviors>Edit

Object Caching Use (Origin Cache Headers) Customize

Minimum TTL = 0

http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html

Add Twitter Bootstrap icon to Input box

Bootstrap 4.x

With Bootstrap 4 (and Font Awesome), we still can use the input-group wrapper around our form-control element, and now we can use an input-group-append (or input-group-prepend) wrapper with an input-group-text to get the job done:

<div class="input-group mb-3">
  <input type="text" class="form-control" placeholder="Search" aria-label="Search" aria-describedby="my-search">
  <div class="input-group-append">
    <span class="input-group-text" id="my-search"><i class="fas fa-filter"></i></span>
  </div>
</div>

It will look something like this (thanks to KyleMit for the screenshot):

enter image description here

Learn more by visiting the Input group documentation.

How to make all controls resize accordingly proportionally when window is maximized?

In WPF there are certain 'container' controls that automatically resize their contents and there are some that don't.

Here are some that do not resize their contents (I'm guessing that you are using one or more of these):

StackPanel
WrapPanel
Canvas
TabControl

Here are some that do resize their contents:

Grid
UniformGrid
DockPanel

Therefore, it is almost always preferable to use a Grid instead of a StackPanel unless you do not want automatic resizing to occur. Please note that it is still possible for a Grid to not size its inner controls... it all depends on your Grid.RowDefinition and Grid.ColumnDefinition settings:

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="100" /> <!--<<< Exact Height... won't resize -->
        <RowDefinition Height="Auto" /> <!--<<< Will resize to the size of contents -->
        <RowDefinition Height="*" /> <!--<<< Will resize taking all remaining space -->
    </Grid.RowDefinitions>
</Grid>

You can find out more about the Grid control from the Grid Class page on MSDN. You can also find out more about these container controls from the WPF Container Controls Overview page on MSDN.

Further resizing can be achieved using the FrameworkElement.HorizontalAlignment and FrameworkElement.VerticalAlignment properties. The default value of these properties is Stretch which will stretch elements to fit the size of their containing controls. However, when they are set to any other value, the elements will not stretch.

UPDATE >>>

In response to the questions in your comment:

Use the Grid.RowDefinition and Grid.ColumnDefinition settings to organise a basic structure first... it is common to add Grid controls into the cells of outer Grid controls if need be. You can also use the Grid.ColumnSpan and Grid.RowSpan properties to enable controls to span multiple columns and/or rows of a Grid.

It is most common to have at least one row/column with a Height/Width of "*" which will fill all remaining space, but you can have two or more with this setting, in which case the remaining space will be split between the two (or more) rows/columns. 'Auto' is a good setting to use for the rows/columns that are not set to '"*"', but it really depends on how you want the layout to be.

There is no Auto setting that you can use on the controls in the cells, but this is just as well, because we want the Grid to size the controls for us... therefore, we don't want to set the Height or Width of these controls at all.

The point that I made about the FrameworkElement.HorizontalAlignment and FrameworkElement.VerticalAlignment properties was just to let you know of their existence... as their default value is already Stretch, you don't generally need to set them explicitly.

The Margin property is generally just used to space your controls out evenly... if you drag and drop controls from the Visual Studio Toolbox, VS will set the Margin property to place your control exactly where you dropped it but generally, this is not what we want as it will mess with the auto sizing of controls. If you do this, then just delete or edit the Margin property to suit your needs.

What is difference between CrudRepository and JpaRepository interfaces in Spring Data JPA?

JpaRepository extends PagingAndSortingRepository which in turn extends CrudRepository.

Their main functions are:

Because of the inheritance mentioned above, JpaRepository will have all the functions of CrudRepository and PagingAndSortingRepository. So if you don't need the repository to have the functions provided by JpaRepository and PagingAndSortingRepository , use CrudRepository.

Changing the color of an hr element

You can give the <hr noshade> tag and go to your css file and add :

_x000D_
_x000D_ 
hr {_x000D_
    border-top:0;_x000D_
    color: #123455;_x000D_
}
_x000D_ 
<hr noshade />_x000D_
This s a test_x000D_
<hr noshade />
_x000D_
_x000D_
_x000D_

Regex to match alphanumeric and spaces

just a FYI

string clean = Regex.Replace(q, @"[^a-zA-Z0-9\s]", string.Empty);

would actually be better like

string clean = Regex.Replace(q, @"[^\w\s]", string.Empty);

Using a cursor with dynamic SQL in a stored procedure

Working with a non-relational database (IDMS anyone?) over an ODBC connection qualifies as one of those times where cursors and dynamic SQL seems the only route.

select * from a where a=1 and b in (1,2)

takes 45 minutes to respond while re-written to use keysets without the in clause will run in under 1 second:

select * from a where (a=1 and b=1)
union all
select * from a where (a=1 and b=2)

If the in statement for column B contains 1145 rows, using a cursor to create indidivudal statements and execute them as dynamic SQL is far faster than using the in clause. Silly hey?

And yes, there's no time in a relational database that cursor's should be used. I just can't believe I've come across an instance where a cursor loop is several magnitudes quicker.

Install IPA with iTunes 12

IPA file are generally executable file for iOS app. Approach used to install IPA in iTunes 12 is different as compared to lower versions.

Simply, add IPA file into iTunes library and search for IPA in apps section of connected device. Click on install and Apply.

Check if a Python list item contains a string inside another string

Use the __contains__() method of Pythons string class.:

a = ['abc-123', 'def-456', 'ghi-789', 'abc-456']
for i in a:
    if i.__contains__("abc") :
        print(i, " is containing")

How to execute a shell script from C in Linux?

If you're ok with POSIX, you can also use popen()/pclose()

#include <stdio.h>
#include <stdlib.h>

int main(void) {
/* ls -al | grep '^d' */
  FILE *pp;
  pp = popen("ls -al", "r");
  if (pp != NULL) {
    while (1) {
      char *line;
      char buf[1000];
      line = fgets(buf, sizeof buf, pp);
      if (line == NULL) break;
      if (line[0] == 'd') printf("%s", line); /* line includes '\n' */
    }
    pclose(pp);
  }
  return 0;
}

How to create the pom.xml for a Java project with Eclipse

You should use the new available m2e plugin for Maven integration in Eclipse. With help of that plugin, you should create a new project and move your sources into that project. These are the steps:

  • Check if m2e (or the former m2eclipse) are installed in your Eclipse distribution. If not, install it.
  • Open the "New Project Wizard": File > New > Project...
  • Open Maven and select Maven Project and click Next.
  • Select Create a simple project (to skip the archetype selection).
  • Add the necessary information: Group Id, Artifact Id, Packaging == jar, and a Name.
  • Finish the Wizard.
  • Your new Maven project is now generated, and you are able to move your sources and test packages to the relevant location in your workspace.
  • After that, you can build your project (inside Eclipse) by selecting your project, then calling from the context menu Run as > Maven install.

Can you control how an SVG's stroke-width is drawn?

As people above have noted you'll either have to recalculate an offset to the stroke's path coordinates or double its width and then mask one side or the other, because not only does SVG not natively support Illustrator's stroke alignment, but PostScript doesn't either.

The specification for strokes in Adobe's PostScript Manual 2nd edition states: "4.5.1 Stroking: The stroke operator draws a line of some thickness along the current path. For each straight or curved segment in the path, stroke draws a line that is centered on the segment with sides parallel to the segment." (emphasis theirs)

The rest of the specification has no attributes for offsetting the line's position. When Illustrator lets you align inside or outside, it's recalculating the actual path's offset (because it's still computationally cheaper than overprinting then masking). The path coordinates in the .ai document are reference, not what gets rastered or exported to a final format.

Because Inkscape's native format is spec SVG, it can't offer a feature the spec lacks.

Include CSS and Javascript in my django template

Refer django docs on static files.

In settings.py:

import os
CURRENT_PATH = os.path.abspath(os.path.dirname(__file__).decode('utf-8'))

MEDIA_ROOT = os.path.join(CURRENT_PATH, 'media')

MEDIA_URL = '/media/'

STATIC_ROOT = 'static/'

STATIC_URL = '/static/'

STATICFILES_DIRS = (
                    os.path.join(CURRENT_PATH, 'static'),
)

Then place your js and css files static folder in your project. Not in media folder.

In views.py:

from django.shortcuts import render_to_response, RequestContext

def view_name(request):
    #your stuff goes here
    return render_to_response('template.html', locals(), context_instance = RequestContext(request))

In template.html:

<link rel="stylesheet" type="text/css" href="{{ STATIC_URL }}css/style.css" />
<script type="text/javascript" src="{{ STATIC_URL }}js/jquery-1.8.3.min.js"></script>

In urls.py:

from django.conf import settings
urlpatterns += patterns('',
    url(r'^media/(?P<path>.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT, 'show_indexes': True}),
)

Project file structure can be found here in imgbin.

Get statistics for each group (such as count, mean, etc) using pandas GroupBy?

Swiss Army Knife: GroupBy.describe

Returns count, mean, std, and other useful statistics per-group.

df.groupby(['A', 'B'])['C'].describe()

           count  mean   std   min   25%   50%   75%   max
A   B                                                     
bar one      1.0  0.40   NaN  0.40  0.40  0.40  0.40  0.40
    three    1.0  2.24   NaN  2.24  2.24  2.24  2.24  2.24
    two      1.0 -0.98   NaN -0.98 -0.98 -0.98 -0.98 -0.98
foo one      2.0  1.36  0.58  0.95  1.15  1.36  1.56  1.76
    three    1.0 -0.15   NaN -0.15 -0.15 -0.15 -0.15 -0.15
    two      2.0  1.42  0.63  0.98  1.20  1.42  1.65  1.87

To get specific statistics, just select them,

df.groupby(['A', 'B'])['C'].describe()[['count', 'mean']]

           count      mean
A   B                     
bar one      1.0  0.400157
    three    1.0  2.240893
    two      1.0 -0.977278
foo one      2.0  1.357070
    three    1.0 -0.151357
    two      2.0  1.423148

describe works for multiple columns (change ['C'] to ['C', 'D']—or remove it altogether—and see what happens, the result is a MultiIndexed columned dataframe).

You also get different statistics for string data. Here's an example,

df2 = df.assign(D=list('aaabbccc')).sample(n=100, replace=True)

with pd.option_context('precision', 2):
    display(df2.groupby(['A', 'B'])
               .describe(include='all')
               .dropna(how='all', axis=1))

              C                                                   D                
          count  mean       std   min   25%   50%   75%   max count unique top freq
A   B                                                                              
bar one    14.0  0.40  5.76e-17  0.40  0.40  0.40  0.40  0.40    14      1   a   14
    three  14.0  2.24  4.61e-16  2.24  2.24  2.24  2.24  2.24    14      1   b   14
    two     9.0 -0.98  0.00e+00 -0.98 -0.98 -0.98 -0.98 -0.98     9      1   c    9
foo one    22.0  1.43  4.10e-01  0.95  0.95  1.76  1.76  1.76    22      2   a   13
    three  15.0 -0.15  0.00e+00 -0.15 -0.15 -0.15 -0.15 -0.15    15      1   c   15
    two    26.0  1.49  4.48e-01  0.98  0.98  1.87  1.87  1.87    26      2   b   15

For more information, see the documentation.

pandas >= 1.1: DataFrame.value_counts

This is available from pandas 1.1 if you just want to capture the size of every group, this cuts out the GroupBy and is faster.

df.value_counts(subset=['col1', 'col2'])

Minimal Example

# Setup
np.random.seed(0)
df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
                          'foo', 'bar', 'foo', 'foo'],
                   'B' : ['one', 'one', 'two', 'three',
                          'two', 'two', 'one', 'three'],
                   'C' : np.random.randn(8),
                   'D' : np.random.randn(8)})

df.value_counts(['A', 'B']) 

A    B    
foo  two      2
     one      2
     three    1
bar  two      1
     three    1
     one      1
dtype: int64

Other Statistical Analysis Tools

If you didn't find what you were looking for above, the User Guide has a comprehensive listing of supported statical analysis, correlation, and regression tools.

WPF: simple TextBox data binding

Just for future needs.

In Visual Studio 2013 with .NET Framework 4.5, for a window property, try adding ElementName=window to make it work.

<Grid Name="myGrid" Height="437.274">
  <TextBox Text="{Binding Path=Name2, ElementName=window}"/>
</Grid>

C# event with custom arguments

Example with no parameters:

delegate void NewEventHandler();
public event NewEventHandler OnEventHappens;

And from another class, you can subscribe to 

otherClass.OnEventHappens += ExecuteThisFunctionWhenEventHappens;

And declare that function with no parameters.

Finding absolute value of a number without using Math.abs()

Since Java is a statically typed language, I would expect that a abs-method which takes an int returns an int, if it expects a float returns a float, for a Double, return a Double. Maybe it could return always the boxed or unboxed type for doubles and Doubles and so on.

So you need one method per type, but now you have a new problem: For byte, short, int, long the range for negative values is 1 bigger than for positive values.

So what should be returned for the method 

byte abs (byte in) {
   // @todo
}

If the user calls abs on -128? You could always return the next bigger type so that the range is guaranteed to fit to all possible input values. This will lead to problems for long, where no normal bigger type exists, and make the user always cast the value down after testing - maybe a hassle.

The second option is to throw an arithmetic exception. This will prevent casting and checking the return type for situations where the input is known to be limited, such that X.MIN_VALUE can't happen. Think of MONTH, represented as int. 

byte abs (byte in) throws ArithmeticException {
   if (in == Byte.MIN_VALUE) throw new ArithmeticException ("abs called on Byte.MIN_VALUE"); 
   return (in < 0) ? (byte) -in : in; 
}

The "let's ignore the rare cases of MIN_VALUE" habit is not an option. First make the code work - then make it fast. If the user needs a faster, but buggy solution, he should write it himself. The simplest solution that might work means: simple, but not too simple.

Since the code doesn't rely on state, the method can and should be made static. This allows for a quick test: 

public static void main (String args []) {
    System.out.println (abs(new Byte ( "7")));
    System.out.println (abs(new Byte ("-7")));
    System.out.println (abs((byte)  7));
    System.out.println (abs((byte) -7));
    System.out.println (abs(new Byte ( "127")));
    try
    {
        System.out.println (abs(new Byte ("-128")));
    }
    catch (ArithmeticException ae)
    {
        System.out.println ("Integer: " + Math.abs (new Integer ("-128")));
    }
    System.out.println (abs((byte)  127));
    System.out.println (abs((byte) -128));
}

I catch the first exception and let it run into the second, just for demonstration.

There is a bad habit in programming, which is that programmers care much more for fast than for correct code. What a pity!

If you're curious why there is one more negative than positive value, I have a diagram for you.

How to prevent auto-closing of console after the execution of batch file

Had problems with the answers here, so I came up with this, which works for me (TM):

cmd /c node_modules\.bin\tsc
cmd /c node rollup_build.js
pause

Automated Python to Java translation

Yes Jython does this, but it may or may not be what you want

Excel Looping through rows and copy cell values to another worksheet

 
Private Sub CommandButton1_Click() 

Dim Z As Long 
Dim Cellidx As Range 
Dim NextRow As Long 
Dim Rng As Range 
Dim SrcWks As Worksheet 
Dim DataWks As Worksheet 
Z = 1 
Set SrcWks = Worksheets("Sheet1") 
Set DataWks = Worksheets("Sheet2") 
Set Rng = EntryWks.Range("B6:ad6") 

NextRow = DataWks.UsedRange.Rows.Count 
NextRow = IIf(NextRow = 1, 1, NextRow + 1) 

For Each RA In Rng.Areas 
    For Each Cellidx In RA 
        Z = Z + 1 
        DataWks.Cells(NextRow, Z) = Cellidx 
    Next Cellidx 
Next RA 
End Sub

Alternatively

Worksheets("Sheet2").Range("P2").Value = Worksheets("Sheet1").Range("L10")

This is a CopynPaste - Method

Sub CopyDataToPlan()

Dim LDate As String
Dim LColumn As Integer
Dim LFound As Boolean

On Error GoTo Err_Execute

'Retrieve date value to search for
LDate = Sheets("Rolling Plan").Range("B4").Value

Sheets("Plan").Select

'Start at column B
LColumn = 2
LFound = False

While LFound = False

  'Encountered blank cell in row 2, terminate search
  If Len(Cells(2, LColumn)) = 0 Then
     MsgBox "No matching date was found."
     Exit Sub

  'Found match in row 2
  ElseIf Cells(2, LColumn) = LDate Then

     'Select values to copy from "Rolling Plan" sheet
     Sheets("Rolling Plan").Select
     Range("B5:H6").Select
     Selection.Copy

     'Paste onto "Plan" sheet
     Sheets("Plan").Select
     Cells(3, LColumn).Select
     Selection.PasteSpecial Paste:=xlValues, Operation:=xlNone, SkipBlanks:= _
     False, Transpose:=False

     LFound = True
     MsgBox "The data has been successfully copied."

     'Continue searching
      Else
         LColumn = LColumn + 1
      End If

   Wend

   Exit Sub

Err_Execute:
  MsgBox "An error occurred."

End Sub

And there might be some methods doing that in Excel.

Java says FileNotFoundException but file exists

An easy fix, which worked for me, is moving my files out of src and into the main folder of the project. It's not the best solution, but depending on the magnitude of the project and your time, it might be just perfect.

Download file from an ASP.NET Web API method using AngularJS

We also had to develop a solution which would even work with APIs requiring authentication (see this article)

Using AngularJS in a nutshell here is how we did it:

Step 1: Create a dedicated directive

// jQuery needed, uses Bootstrap classes, adjust the path of templateUrl
app.directive('pdfDownload', function() {
return {
    restrict: 'E',
    templateUrl: '/path/to/pdfDownload.tpl.html',
    scope: true,
    link: function(scope, element, attr) {
        var anchor = element.children()[0];

        // When the download starts, disable the link
        scope.$on('download-start', function() {
            $(anchor).attr('disabled', 'disabled');
        });

        // When the download finishes, attach the data to the link. Enable the link and change its appearance.
        scope.$on('downloaded', function(event, data) {
            $(anchor).attr({
                href: 'data:application/pdf;base64,' + data,
                download: attr.filename
            })
                .removeAttr('disabled')
                .text('Save')
                .removeClass('btn-primary')
                .addClass('btn-success');

            // Also overwrite the download pdf function to do nothing.
            scope.downloadPdf = function() {
            };
        });
    },
    controller: ['$scope', '$attrs', '$http', function($scope, $attrs, $http) {
        $scope.downloadPdf = function() {
            $scope.$emit('download-start');
            $http.get($attrs.url).then(function(response) {
                $scope.$emit('downloaded', response.data);
            });
        };
    }] 
});

Step 2: Create a template

<a href="" class="btn btn-primary" ng-click="downloadPdf()">Download</a>

Step 3: Use it

<pdf-download url="/some/path/to/a.pdf" filename="my-awesome-pdf"></pdf-download>

This will render a blue button. When clicked, a PDF will be downloaded (Caution: the backend has to deliver the PDF in Base64 encoding!) and put into the href. The button turns green and switches the text to Save. The user can click again and will be presented with a standard download file dialog for the file my-awesome.pdf.

How to put text over images in html?

You can try this...

<div class="image">

      <img src="" alt="" />

      <h2>Text you want to display over the image</h2>

</div>

CSS

.image { 
   position: relative; 
   width: 100%; /* for IE 6 */
}

h2 { 
   position: absolute; 
   top: 200px; 
   left: 0; 
   width: 100%; 
}

Getting index value on razor foreach

IndexOf seems to be useful here.

@foreach (myItemClass ts in Model.ItemList.Where(x => x.Type == "something"))
    {
       int currentIndex = Model.ItemList.IndexOf(ts);
       @Html.HiddenFor(x=>Model.ItemList[currentIndex].Type)

...

href overrides ng-click in Angular.js

Just write ng-click before href ..It worked for me

_x000D_
_x000D_ 
<!DOCTYPE html>_x000D_
<html>_x000D_
_x000D_
  <head>_x000D_
    <script data-require="[email protected]" data-semver="1.5.0" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js"></script>_x000D_
    <script>_x000D_
    angular.module("module",[])_x000D_
.controller("controller",function($scope){_x000D_
  _x000D_
  $scope.func =function(){_x000D_
    console.log("d");_x000D_
  }_x000D_
  _x000D_
})</script>_x000D_
  </head>_x000D_
_x000D_
  <body ng-app="module" ng-controller="controller">_x000D_
    <h1>Hello ..</h1>_x000D_
    <a ng-click="func()" href="someplace.html">Take me there</a>_x000D_
  </body>_x000D_
_x000D_
</html>
_x000D_
_x000D_
_x000D_

Locate current file in IntelliJ

If you are using Mac(OSX)

Based on the current tab, to select the file on project is : FN + OPTION + F1

Then in the popup you can Select in: Project View > Select In: Project

mysql datetime comparison

I know its pretty old but I just encounter the problem and there is what I saw in the SQL doc :

[For best results when using BETWEEN with date or time values,] use CAST() to explicitly convert the values to the desired data type. Examples: If you compare a DATETIME to two DATE values, convert the DATE values to DATETIME values. If you use a string constant such as '2001-1-1' in a comparison to a DATE, cast the string to a DATE.

I assume it's better to use STR_TO_DATE since they took the time to make a function just for that and also the fact that i found this in the BETWEEN doc...

Update Tkinter Label from variable

The window is only displayed once the mainloop is entered. So you won't see any changes you make in your while True block preceding the line root.mainloop().

GUI interfaces work by reacting to events while in the mainloop. Here's an example where the StringVar is also connected to an Entry widget. When you change the text in the Entry widget it automatically changes in the Label.

from tkinter import *

root = Tk()
var = StringVar()
var.set('hello')

l = Label(root, textvariable = var)
l.pack()

t = Entry(root, textvariable = var)
t.pack()

root.mainloop() # the window is now displayed

I like the following reference: tkinter 8.5 reference: a GUI for Python

Here is a working example of what you were trying to do:

from tkinter import *
from time import sleep

root = Tk()
var = StringVar()
var.set('hello')

l = Label(root, textvariable = var)
l.pack()

for i in range(6):
    sleep(1) # Need this to slow the changes down
    var.set('goodbye' if i%2 else 'hello')
    root.update_idletasks()

root.update Enter event loop until all pending events have been processed by Tcl.

Android Support Design TabLayout: Gravity Center and Mode Scrollable

Very simple example and it always works.

/**
 * Setup stretch and scrollable TabLayout.
 * The TabLayout initial parameters in layout must be:
 * android:layout_width="wrap_content"
 * app:tabMaxWidth="0dp"
 * app:tabGravity="fill"
 * app:tabMode="fixed"
 *
 * @param context   your Context
 * @param tabLayout your TabLayout
 */
public static void setupStretchTabLayout(Context context, TabLayout tabLayout) {
    tabLayout.post(() -> {

        ViewGroup.LayoutParams params = tabLayout.getLayoutParams();
        if (params.width == ViewGroup.LayoutParams.MATCH_PARENT) { // is already set up for stretch
            return;
        }

        int deviceWidth = context.getResources()
                                 .getDisplayMetrics().widthPixels;

        if (tabLayout.getWidth() < deviceWidth) {
            tabLayout.setTabMode(TabLayout.MODE_FIXED);
            params.width = ViewGroup.LayoutParams.MATCH_PARENT;
        } else {
            tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
            params.width = ViewGroup.LayoutParams.WRAP_CONTENT;
        }
        tabLayout.setLayoutParams(params);

    });

}

Java 8 Distinct by property

Extending Stuart Marks's answer, this can be done in a shorter way and without a concurrent map (if you don't need parallel streams):

public static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
    final Set<Object> seen = new HashSet<>();
    return t -> seen.add(keyExtractor.apply(t));
}

Then call:

persons.stream().filter(distinctByKey(p -> p.getName());

how to change default python version?

Check the execution path of python3 where it has libraries

$ which python3
/usr/local/bin/python3  some OS might have /usr/bin/python3

open bash_profile file and add an alias

vi ~/.bash_profile  
alias python='/usr/local/bin/python3' or alias python='/usr/bin/python3'

Reload bash_profile to take effect of modifications

source ~/.bash_profile

Run python command and check whether it's getting loading with python3

$ python --version
Python 3.6.5

What's the difference between "static" and "static inline" function?

From my experience with GCC I know that static and static inline differs in a way how compiler issue warnings about unused functions. More precisely when you declare static function and it isn't used in current translation unit then compiler produce warning about unused function, but you can inhibit that warning with changing it to static inline.

Thus I tend to think that static should be used in translation units and benefit from extra check compiler does to find unused functions. And static inline should be used in header files to provide functions that can be in-lined (due to absence of external linkage) without issuing warnings.

Unfortunately I cannot find any evidence for that logic. Even from GCC documentation I wasn't able to conclude that inline inhibits unused function warnings. I'd appreciate if someone will share links to description of that.

How to query all the GraphQL type fields without writing a long query?

Unfortunately what you'd like to do is not possible. GraphQL requires you to be explicit about specifying which fields you would like returned from your query.

Fit image into ImageView, keep aspect ratio and then resize ImageView to image dimensions?

I needed to get this done in a constraint layout with Picasso, so I munged together some of the above answers and came up with this solution (I already know the aspect ratio of the image I'm loading, so that helps):

Called in my activity code somewhere after setContentView(...)

protected void setBoxshotBackgroundImage() {
    ImageView backgroundImageView = (ImageView) findViewById(R.id.background_image_view);

    if(backgroundImageView != null) {
        DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        int width = displayMetrics.widthPixels;
        int height = (int) Math.round(width * ImageLoader.BOXART_HEIGHT_ASPECT_RATIO);

        // we adjust the height of this element, as the width is already pinned to the parent in xml
        backgroundImageView.getLayoutParams().height = height;

        // implement your Picasso loading code here
    } else {
        // fallback if no element in layout...
    }
}

In my XML

<?xml version="1.0" encoding="utf-8"?>

<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteY="0dp"
tools:layout_editor_absoluteX="0dp">

    <ImageView
        android:id="@+id/background_image_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:scaleType="fitStart"
        app:srcCompat="@color/background"
        android:adjustViewBounds="true"
        tools:layout_editor_absoluteY="0dp"
        android:layout_marginTop="0dp"
        android:layout_marginBottom="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginLeft="0dp"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <!-- other elements of this layout here... -->

</android.support.constraint.ConstraintLayout>

Note the lack of a constraintBottom_toBottomOf attribute. ImageLoader is my own static class for image loading util methods and constants.

Getting time difference between two times in PHP

 
<?php
$start = strtotime("12:00");
$end = // Run query to get datetime value from db
$elapsed = $end - $start;
echo date("H:i", $elapsed);
?>

What is the difference between a schema and a table and a database?

In oracle Schema is one user under one database,For example scott is one schema in database orcl. In one database we may have many schema's like scott

Page scroll up or down in Selenium WebDriver (Selenium 2) using java

 
JavascriptExecutor jse = (JavascriptExecutor)driver;
jse.executeScript("window.scrollBy(0,250)");

Send Email to multiple Recipients with MailMessage?

According to the Documentation :

MailMessage.To property - Returns MailAddressCollection that contains the list of recipients of this email message

Here MailAddressCollection has a in built method called 

   public void Add(string addresses)

   1. Summary:
          Add a list of email addresses to the collection.

   2. Parameters:
          addresses: 
                *The email addresses to add to the System.Net.Mail.MailAddressCollection. Multiple
                *email addresses must be separated with a comma character (",").

Therefore requirement in case of multiple recipients : Pass a string that contains email addresses separated by comma

In your case :

simply replace all the ; with , 

Msg.To.Add(toEmail.replace(";", ","));

For reference :

  1. https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.mailmessage?view=netframework-4.8
  2. https://www.geeksforgeeks.org/c-sharp-replace-method/

How to test my servlet using JUnit

Use Selenium for webbased unit tests. There's a Firefox plugin called Selenium IDE which can record actions on the webpage and export to JUnit testcases which uses Selenium RC to run the test server.

How to compile multiple java source files in command line

Here is another example, for compiling a java file in a nested directory.

I was trying to build this from the command line. This is an example from 'gradle', which has dependency 'commons-collection.jar'. For more info, please see 'gradle: java quickstart' example. -- of course, you would use the 'gradle' tools to build it. But i thought to extend this example, for a nested java project, with a dependent jar.

Note: You need the 'gradle binary or source' distribution for this, example code is in: 'samples/java/quickstart'

% mkdir -p temp/classes
% curl --get \
    http://central.maven.org/maven2/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar \
        --output commons-collections-3.2.2.jar

% javac -g -classpath commons-collections-3.2.2.jar \
     -sourcepath src/main/java -d temp/classes \
      src/main/java/org/gradle/Person.java 

% jar cf my_example.jar -C temp/classes org/gradle/Person.class
% jar tvf my_example.jar
   0 Wed Jun 07 14:11:56 CEST 2017 META-INF/
  69 Wed Jun 07 14:11:56 CEST 2017 META-INF/MANIFEST.MF
 519 Wed Jun 07 13:58:06 CEST 2017 org/gradle/Person.class

How to add an Access-Control-Allow-Origin header

Check this link.. It will definitely solve your problem.. There are plenty of solutions to make cross domain GET Ajax calls BUT POST REQUEST FOR CROSS DOMAIN IS SOLVED HERE. It took me 3 days to figure it out.

http://blogs.msdn.com/b/carlosfigueira/archive/2012/02/20/implementing-cors-support-in-asp-net-web-apis.aspx

is there a 'block until condition becomes true' function in java?

You could use a semaphore.

While the condition is not met, another thread acquires the semaphore.
Your thread would try to acquire it with acquireUninterruptibly()
or tryAcquire(int permits, long timeout, TimeUnit unit) and would be blocked.

When the condition is met, the semaphore is also released and your thread would acquire it.

You could also try using a SynchronousQueue or a CountDownLatch.

How to enable CORS on Firefox?

I was stucked with this problem for a long time (CORS does not work in FF, but works in Chrome and others). No advice could help. Finally, i found that my local dev subdomain (like sub.example.dev) was not explicitly mentioned in /etc/hosts, thus FF just is not able to find it and shows confusing error message 'Aborted...' in dev tools panel.

Putting the exact subdomain into my local /etc/hosts fixed the problem. /etc/hosts is just a plain-text file in unix systems, so you can open it under the root user and put your subdomain in front of '127.0.0.1' ip address.

XMLHttpRequest cannot load file. Cross origin requests are only supported for HTTP

Depends on your needs, but there is also a quick way to temporarily check your (dummy) JSON by saving your JSON on http://myjson.com. Copy the api link and paste that into your javascript code. Viola! When you want to deploy the codes, you must not forget to change that url in your codes!

How to "grep" for a filename instead of the contents of a file?

The easiest way is 

find . | grep test

here find will list all the files in the (.) ie current directory, recursively. And then it is just a simple grep. all the files which name has "test" will appeared.

you can play with grep as per your requirement. Note : As the grep is generic string classification, It can result in giving you not only file names. but if a path has a directory ('/xyz_test_123/other.txt') would also comes to the result set. cheers

List comprehension vs map

If you plan on writing any asynchronous, parallel, or distributed code, you will probably prefer map over a list comprehension -- as most asynchronous, parallel, or distributed packages provide a map function to overload python's map. Then by passing the appropriate map function to the rest of your code, you may not have to modify your original serial code to have it run in parallel (etc).

Copy data from one column to other column (which is in a different table)

A similar question's answer worked more correctly for me than this question's selected answer (by Mark Byers). Using Mark's answer, my updated column got the same value in all the rows (perhaps the value from the first row that matched the join). Using ParveenaArora's answer from the other thread updated the column with the correct values.

Transforming Parveena's solution to use this question' table and column names, the query would be as follows (where I assume the tables are related through tblindiantime.contact_id):

UPDATE tblindiantime
SET CountryName = contacts.BusinessCountry
FROM contacts
WHERE tblindiantime.contact_id = contacts.id;

What is a quick way to force CRLF in C# / .NET?

Simple variant:

Regex.Replace(input, @"\r\n|\r|\n", "\r\n")

For better performance:

static Regex newline_pattern = new Regex(@"\r\n|\r|\n", RegexOptions.Compiled);
[...]
    newline_pattern.Replace(input, "\r\n");

How can I properly use a PDO object for a parameterized SELECT query

A litle bit complete answer is here with all ready for use:

    $sql = "SELECT `username` FROM `users` WHERE `id` = :id";
    $q = $dbh->prepare($sql);
    $q->execute(array(':id' => "4"));
    $done= $q->fetch();

 echo $done[0];

Here $dbh is PDO db connecter, and based on id from table users we've get the username using fetch();

I hope this help someone, Enjoy!

Python urllib2, basic HTTP authentication, and tr.im

This seems to work really well (taken from another thread)

import urllib2, base64

request = urllib2.Request("http://api.foursquare.com/v1/user")
base64string = base64.encodestring('%s:%s' % (username, password)).replace('\n', '')
request.add_header("Authorization", "Basic %s" % base64string)   
result = urllib2.urlopen(request)

Get data from fs.readFile

 
var path = "index.html"

const readFileAsync = fs.readFileSync(path, 'utf8');
// console.log(readFileAsync)

using simple readFileSync works for me.

Unable to create a constant value of type Only primitive types or enumeration types are supported in this context

In my case, I was able to resolve the issue by doing the following:

I changed my code from this:

var r2 = db.Instances.Where(x => x.Player1 == inputViewModel.InstanceList.FirstOrDefault().Player2 && x.Player2 == inputViewModel.InstanceList.FirstOrDefault().Player1).ToList();

To this:

var p1 = inputViewModel.InstanceList.FirstOrDefault().Player1;
var p2 = inputViewModel.InstanceList.FirstOrDefault().Player2;
var r1 = db.Instances.Where(x => x.Player1 == p1 && x.Player2 == p2).ToList();

Can we create an instance of an interface in Java?

Yes it is correct. you can do it with an inner class.

ansible : how to pass multiple commands

If a value in YAML begins with a curly brace ({), the YAML parser assumes that it is a dictionary. So, for cases like this where there is a (Jinja2) variable in the value, one of the following two strategies needs to be adopted to avoiding confusing the YAML parser:

Quote the whole command:

- command: "{{ item }} chdir=/src/package/"
  with_items:
  - ./configure
  - /usr/bin/make
  - /usr/bin/make install

or change the order of the arguments:

- command: chdir=/src/package/ {{ item }}
  with_items:
  - ./configure
  - /usr/bin/make
  - /usr/bin/make install

Thanks for @RamondelaFuente alternative suggestion.

Convert Bitmap to File

Hope this helps u

class MainActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    // Get the bitmap from assets and display into image view
    val bitmap = assetsToBitmap("tulip.jpg")
    // If bitmap is not null
    bitmap?.let {
        image_view_bitmap.setImageBitmap(bitmap)
    }


    // Click listener for button widget
    button.setOnClickListener{
        if(bitmap!=null){
            // Save the bitmap to a file and display it into image view
            val uri = bitmapToFile(bitmap)
            image_view_file.setImageURI(uri)

            // Display the saved bitmap's uri in text view
            text_view.text = uri.toString()

            // Show a toast message
            toast("Bitmap saved in a file.")
        }else{
            toast("bitmap not found.")
        }
    }
}


// Method to get a bitmap from assets
private fun assetsToBitmap(fileName:String):Bitmap?{
    return try{
        val stream = assets.open(fileName)
        BitmapFactory.decodeStream(stream)
    }catch (e:IOException){
        e.printStackTrace()
        null
    }
}


// Method to save an bitmap to a file
private fun bitmapToFile(bitmap:Bitmap): Uri {
    // Get the context wrapper
    val wrapper = ContextWrapper(applicationContext)

    // Initialize a new file instance to save bitmap object
    var file = wrapper.getDir("Images",Context.MODE_PRIVATE)
    file = File(file,"${UUID.randomUUID()}.jpg")

    try{
        // Compress the bitmap and save in jpg format
        val stream:OutputStream = FileOutputStream(file)
        bitmap.compress(Bitmap.CompressFormat.JPEG,100,stream)
        stream.flush()
        stream.close()
    }catch (e:IOException){
        e.printStackTrace()
    }

    // Return the saved bitmap uri
    return Uri.parse(file.absolutePath)
}

}

android image button

You can just set the onClick of an ImageView and also set it to be clickable, Or set the drawableBottom property of a regular button.

    ImageView iv = (ImageView)findViewById(R.id.ImageView01);
   iv.setOnClickListener(new OnClickListener() {
   public void onClick(View v) {
    // TODO Auto-generated method stub

   }
   });

Age from birthdate in python

 
from datetime import date

def age(birth_date):
    today = date.today()
    y = today.year - birth_date.year
    if today.month < birth_date.month or today.month == birth_date.month and today.day < birth_date.day:
        y -= 1
    return y

ORA-12154 could not resolve the connect identifier specified

There can be so many issues but if you are using oracle 10g , uninstall oracle 10g and also remove the value from registry and install oracle 11g. But if you are using oracle 11g , first go and check on registry if it is pointing to right home. Sometimes there can be more than one home because you install sql developer again and again . In that case either you can remove unnecessary home registry value or you can add tns and sql.net file to all of those home, that might resolve the issue. I resolved mine in that way.

(grep) Regex to match non-ASCII characters?

You can use this regex:

[^\w \xC0-\xFF]

Case ask, the options is Multiline.

SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified

In my instance, the name of the connectionString in the web.config file was spelled wrong. This is the name of the database context Entity Framework uses. I guess this is the error you get when EF can't match up the connectionString name with the context.

how to start stop tomcat server using CMD?

Add %CATALINA_HOME%/bin to path system variable.

Go to Environment Variables screen under System Variables there will be a Path variable edit the variable and add ;%CATALINA_HOME%\bin to the variable then click OK to save the changes. Close all opened command prompts then open a new command prompt and try to use the command startup.bat.

Could not calculate build plan: Plugin org.apache.maven.plugins:maven-resources-plugin:2.5 or one of its dependencies could not be resolved

I have shifted my project to a different machine, copied all my maven libraries from old machine to new machine, did Right click on my project >> Maven >> Update Project. And then built my project. In addition to this, I have also done this one step which is shown in screenshot. And that's all it worked!!

Go to Window --> Preferences --> Maven --> User Setting, make sure you have these settings..
enter image description here

Also Right click on your project --> Properties --> Maven, and make sure you have the path here to maven repository..
enter image description here

Python and SQLite: insert into table

This will work for a multiple row df having the dataframe as df with the same name of the columns in the df as the db.

tuples = list(df.itertuples(index=False, name=None))

columns_list = df.columns.tolist()
marks = ['?' for _ in columns_list]
columns_list = f'({(",".join(columns_list))})'
marks = f'({(",".join(marks))})'

table_name = 'whateveryouwant'

c.executemany(f'INSERT OR REPLACE INTO {table_name}{columns_list} VALUES {marks}', tuples)
conn.commit()

VHDL - How should I create a clock in a testbench?

How to use a clock and do assertions

This example shows how to generate a clock, and give inputs and assert outputs for every cycle. A simple counter is tested here.

The key idea is that the process blocks run in parallel, so the clock is generated in parallel with the inputs and assertions.

library ieee;
use ieee.std_logic_1164.all;

entity counter_tb is
end counter_tb;

architecture behav of counter_tb is
    constant width : natural := 2;
    constant clk_period : time := 1 ns;

    signal clk : std_logic := '0';
    signal data : std_logic_vector(width-1 downto 0);
    signal count : std_logic_vector(width-1 downto 0);

    type io_t is record
        load : std_logic;
        data : std_logic_vector(width-1 downto 0);
        count : std_logic_vector(width-1 downto 0);
    end record;
    type ios_t is array (natural range <>) of io_t;
    constant ios : ios_t := (
        ('1', "00", "00"),
        ('0', "UU", "01"),
        ('0', "UU", "10"),
        ('0', "UU", "11"),

        ('1', "10", "10"),
        ('0', "UU", "11"),
        ('0', "UU", "00"),
        ('0', "UU", "01")
    );
begin
    counter_0: entity work.counter port map (clk, load, data, count);

    process
    begin
        for i in ios'range loop
            load <= ios(i).load;
            data <= ios(i).data;
            wait until falling_edge(clk);
            assert count = ios(i).count;
        end loop;
        wait;
    end process;

    process
    begin
        for i in 1 to 2 * ios'length loop
            wait for clk_period / 2;
            clk <= not clk;
        end loop;
        wait;
    end process;
end behav;

The counter would look like this:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all; -- unsigned

entity counter is
    generic (
        width : in natural := 2
    );
    port (
        clk, load : in std_logic;
        data : in std_logic_vector(width-1 downto 0);
        count : out std_logic_vector(width-1 downto 0)
    );
end entity counter;

architecture rtl of counter is
    signal cnt : unsigned(width-1 downto 0);
begin
    process(clk) is
    begin
        if rising_edge(clk) then
            if load = '1' then
                cnt <= unsigned(data);
            else
                cnt <= cnt + 1;
            end if;
        end if;
    end process;
    count <= std_logic_vector(cnt);
end architecture rtl;

Related: https://electronics.stackexchange.com/questions/148320/proper-clock-generation-for-vhdl-testbenches

How many characters can you store with 1 byte?

Yes, 1 byte does encode a character (inc spaces etc) from the ASCII set. However in data units assigned to character encoding it can and often requires in practice up to 4 bytes. This is because English is not the only character set. And even in English documents other languages and characters are often represented. The numbers of these are very many and there are very many other encoding sets, which you may have heard of e.g. BIG-5, UTF-8, UTF-32. Most computers now allow for these uses and ensure the least amount of garbled text (which usually means a missing encoding set.) 4 bytes is enough to cover these possible encodings. I byte per character does not allow for this and in use it is larger often 4 bytes per possible character for all encodings, not just ASCII. The final character may only need a byte to function or be represented on screen, but requires 4 bytes to be located in the rather vast global encoding "works".

How to select the rows with maximum values in each group with dplyr?

Try this:

result <- df %>% 
             group_by(A, B) %>%
             filter(value == max(value)) %>%
             arrange(A,B,C)

Seems to work:

identical(
  as.data.frame(result),
  ddply(df, .(A, B), function(x) x[which.max(x$value),])
)
#[1] TRUE

As pointed out in the comments, slice may be preferred here as per @RoyalITS' answer below if you strictly only want 1 row per group. This answer will return multiple rows if there are multiple with an identical maximum value.

Post Build exited with code 1

As a matter of good practice I suggest you replace the post build event with a MS Build File Copy task.

Change background color of R plot

Old question but I have a much better way of doing this. Rather than using rect() use polygon. This allows you to keep everything in plot without using points. Also you don't have to mess with par at all. If you want to keep things automated make the coordinates of polygon a function of your data. 

plot.new()
polygon(c(-min(df[,1])^2,-min(df[,1])^2,max(df[,1])^2,max(df[,1])^2),c(-min(df[,2])^2,max(df[,2])^2,max(df[,2])^2,-min(df[,2])^2), col="grey")
par(new=T)
plot(df)

long long int vs. long int vs. int64_t in C++

You don't need to go to 64-bit to see something like this. Consider int32_t on common 32-bit platforms. It might be typedef'ed as int or as a long, but obviously only one of the two at a time. int and long are of course distinct types.

It's not hard to see that there is no workaround which makes int == int32_t == long on 32-bit systems. For the same reason, there's no way to make long == int64_t == long long on 64-bit systems.

If you could, the possible consequences would be rather painful for code that overloaded foo(int), foo(long) and foo(long long) - suddenly they'd have two definitions for the same overload?!

The correct solution is that your template code usually should not be relying on a precise type, but on the properties of that type. The whole same_type logic could still be OK for specific cases:

long foo(long x);
std::tr1::disable_if(same_type(int64_t, long), int64_t)::type foo(int64_t);

I.e., the overload foo(int64_t) is not defined when it's exactly the same as foo(long).

[edit] With C++11, we now have a standard way to write this:

long foo(long x);
std::enable_if<!std::is_same<int64_t, long>::value, int64_t>::type foo(int64_t);

[edit] Or C++20

long foo(long x);
int64_t foo(int64_t) requires (!std::is_same_v<int64_t, long>);

Editable text to string

If I understand correctly, you want to get the String of an Editable object, right? If yes, try using toString().

Why em instead of px?

example:

Code: body{font-size:10px;} //keep at 10 all sizes below correct, change this value and the rest change to be e.g. 1.4 of this value

1{font-size:1.2em;} //12px

2{font-size:1.4em;} //14px

3{font-size:1.6em;} //16px

4{font-size:1.8em;} //18px

5{font-size:2em;} //20px

…

body

1

2

3

4

5

by changing the value in body the rest change automatically to be a kind of times the base value…

10×2=20 10×1.6=16 etc

you could have the base value as 8px… so 8×2=16 8×1.6=12.8 //may be rounded by browser

Loop until a specific user input

Your code won't work because you haven't assigned anything to n before you first use it. Try this:

def oracle():
    n = None
    while n != 'Correct':
        # etc...

A more readable approach is to move the test until later and use a break:

def oracle():
    guess = 50

    while True:
        print 'Current number = {0}'.format(guess)
        n = raw_input("lower, higher or stop?: ")
        if n == 'stop':
            break
        # etc...

Also input in Python 2.x reads a line of input and then evaluates it. You want to use raw_input.

Note: In Python 3.x, raw_input has been renamed to input and the old input method no longer exists.

Removing specific rows from a dataframe

One simple solution:

cond1 <- df$sub == 1 & df$day == 2

cond2 <- df$sub == 3 & df$day == 4

df <- df[!(cond1 | cond2),]

Undo working copy modifications of one file in Git?

For me only this one worked

git checkout -p filename

enter image description here

push_back vs emplace_back

emplace_back shouldn't take an argument of type vector::value_type, but instead variadic arguments that are forwarded to the constructor of the appended item.

template <class... Args> void emplace_back(Args&&... args);

It is possible to pass a value_type which will be forwarded to the copy constructor.

Because it forwards the arguments, this means that if you don't have rvalue, this still means that the container will store a "copied" copy, not a moved copy.

 std::vector<std::string> vec;
 vec.emplace_back(std::string("Hello")); // moves
 std::string s;
 vec.emplace_back(s); //copies

But the above should be identical to what push_back does. It is probably rather meant for use cases like:

 std::vector<std::pair<std::string, std::string> > vec;
 vec.emplace_back(std::string("Hello"), std::string("world")); 
 // should end up invoking this constructor:
 //template<class U, class V> pair(U&& x, V&& y);
 //without making any copies of the strings

ORA-01653: unable to extend table by in tablespace ORA-06512

You could also turn on autoextend for the whole database using this command:

ALTER DATABASE DATAFILE 'C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSTEM.DBF'
AUTOEXTEND ON NEXT 1M MAXSIZE 1024M;

Just change the filepath to point to your system.dbf file.

Credit Here

VBA Excel - Insert row below with same format including borders and frames

well, using the Macro record, and doing it manually, I ended up with this code .. which seems to work .. (although it's not a one liner like yours ;)

lrow = Selection.Row()
Rows(lrow).Select
Selection.Copy
Rows(lrow + 1).Select
Selection.Insert Shift:=xlDown
Application.CutCopyMode = False
Selection.ClearContents

(I put the ClearContents in there because you indicated you wanted format, and I'm assuming you didn't want the data ;) )

What's a good (free) visual merge tool for Git? (on windows)

What's wrong with using Git For Windows? From the repo view, there's an icon of the branch you're in (at the top), and if you click on manage you can drag&drop in a very visual and convenient way.

Getting the array length of a 2D array in Java

With Java 8, allow you doing something more elegant like this:

int[][] foo = new int[][] {
        new int[] { 1, 2, 3 },
        new int[] { 1, 2, 3, 4},
    };

int length = Arrays.stream(array).max(Comparator.comparingInt(ArrayUtils::getLength)).get().length

Difference between matches() and find() in Java Regex

matches() will only return true if the full string is matched. find() will try to find the next occurrence within the substring that matches the regex. Note the emphasis on "the next". That means, the result of calling find() multiple times might not be the same. In addition, by using find() you can call start() to return the position the substring was matched. 

final Matcher subMatcher = Pattern.compile("\\d+").matcher("skrf35kesruytfkwu4ty7sdfs");
System.out.println("Found: " + subMatcher.matches());
System.out.println("Found: " + subMatcher.find() + " - position " + subMatcher.start());
System.out.println("Found: " + subMatcher.find() + " - position " + subMatcher.start());
System.out.println("Found: " + subMatcher.find() + " - position " + subMatcher.start());
System.out.println("Found: " + subMatcher.find());
System.out.println("Found: " + subMatcher.find());
System.out.println("Matched: " + subMatcher.matches());

System.out.println("-----------");
final Matcher fullMatcher = Pattern.compile("^\\w+$").matcher("skrf35kesruytfkwu4ty7sdfs");
System.out.println("Found: " + fullMatcher.find() + " - position " + fullMatcher.start());
System.out.println("Found: " + fullMatcher.find());
System.out.println("Found: " + fullMatcher.find());
System.out.println("Matched: " + fullMatcher.matches());
System.out.println("Matched: " + fullMatcher.matches());
System.out.println("Matched: " + fullMatcher.matches());
System.out.println("Matched: " + fullMatcher.matches());

Will output:

Found: false
Found: true - position 4
Found: true - position 17
Found: true - position 20
Found: false
Found: false
Matched: false
-----------
Found: true - position 0
Found: false
Found: false
Matched: true
Matched: true
Matched: true
Matched: true

So, be careful when calling find() multiple times if the Matcher object was not reset, even when the regex is surrounded with ^ and $ to match the full string.

How to disable HTML button using JavaScript?

If you have the button object, called b: b.disabled=false;

How to find and restore a deleted file in a Git repository

Find the commit that deleted your file:

git log --diff-filter=D --oneline -- path/to/file | cut -f -d ' '

Sample output:

4711174

As of Git 2.23 there is actually a restore command. It is still experimental but in order to restore something you removed in a commit (4711174 in this case) you can then type:

git restore --source=4711174^ path/to/file

Note the ^ after the commit id as we want to restore something from the commit before the one that deleted the file.

The --source argument tells the restore command where to look for the file(s) to restore and it can be any commit and even the index.

See: git-restore doc for git 2.23.0

Return string without trailing slash

 
function someFunction(site) {
  if (site.indexOf('/') > 0)
    return site.substring(0, site.indexOf('/'));
  return site;
}

What is the use of the @Temporal annotation in Hibernate?

use this 

@Temporal(TemporalType.TIMESTAMP)
@Column(name="create_date")
private Calendar createDate;

public Calendar getCreateDate() {
    return createDate;
}

public void setCreateDate(Calendar createDate) {
    this.createDate = createDate;
}

Why doesn't logcat show anything in my Android?

The simplest solution worked for me: Shutdown and restart my phone and Eclipse alike.

What happens when a duplicate key is put into a HashMap?

 
         HashMap<Emp, Emp> empHashMap = new HashMap<Emp, Emp>();

         empHashMap.put(new Emp(1), new Emp(1));
         empHashMap.put(new Emp(1), new Emp(1));
         empHashMap.put(new Emp(1), new Emp());
         empHashMap.put(new Emp(1), new Emp());
         System.out.println(empHashMap.size());
    }
}

class Emp{
    public Emp(){   
    }
    public Emp(int id){
        this.id = id;
    }
    public int id;
    @Override
    public boolean equals(Object obj) {
        return this.id == ((Emp)obj).id;
    }

    @Override
    public int hashCode() {
        return id;
    }
}


OUTPUT : is 1

Means hash map wont allow duplicates, if you have properly overridden equals and hashCode() methods.

HashSet also uses HashMap internally, see the source doc

public class HashSet{
public HashSet() {
        map = new HashMap<>();
    }
}

Explanation of 'String args[]' and static in 'public static void main(String[] args)'
  • public : it is a access specifier that means it will be accessed by publically.
  • static : it is access modifier that means when the java program is load then it will create the space in memory automatically.
  • void : it is a return type i.e it does not return any value.
  • main() : it is a method or a function name.
  • string args[] : its a command line argument it is a collection of variables in the string format.

Linux command line howto accept pairing for bluetooth device without pin

 
~ $ hciconfig noauth

This should do the trick (I'm using bluez 5.23 and there's no more simple-egent and blue-utils). However, I'm trying to look for a way to make changes hciconfig permanent because after power out and then power on, authentication is needed again. So far, the changes in hciconfig still stays the same when you reboot it. it reverts back only when power out. If anybody has found a way to make hciconfig permanent, do let me know!

5.7.57 SMTP - Client was not authenticated to send anonymous mail during MAIL FROM error

Probably the password of the account that you trying to send e-mail is expired. Just check your password policy expire date.

"Post Image data using POSTMAN"

That's not how you send file on postman. What you did is sending a string which is the path of your image, nothing more.

What you should do is;

  1. After setting request method to POST, click to the 'body' tab.
  2. Select form-data. At first line, you'll see text boxes named key and value. Write 'image' to the key. You'll see value type which is set to 'text' as default. Make it File and upload your file.
  3. Then select 'raw' and paste your json file. Also just next to the binary choice, You'll see 'Text' is clicked. Make it JSON.

form-data section

raw section

You're ready to go.

In your Django view,

from rest_framework.views import APIView
from rest_framework.parsers import MultiPartParser
from rest_framework.decorators import parser_classes

@parser_classes((MultiPartParser, ))
class UploadFileAndJson(APIView):

    def post(self, request, format=None):
        thumbnail = request.FILES["file"]
        info = json.loads(request.data['info'])
        ...
        return HttpResponse()

ORA-01017 Invalid Username/Password when connecting to 11g database from 9i client

I had a similar issue some time ago. You must be careful with quotes and double quotes. It's recommended to reset the user password, using a admin credentials.

ALTER USER user_name IDENTIFIED BY new_password;

But don't use double quotes in both parameters.

What is the meaning of {...this.props} in Reactjs

It's called spread attributes and its aim is to make the passing of props easier.

Let us imagine that you have a component that accepts N number of properties. Passing these down can be tedious and unwieldy if the number grows.

<Component x={} y={} z={} />

Thus instead you do this, wrap them up in an object and use the spread notation

var props = { x: 1, y: 1, z:1 };
<Component {...props} />

which will unpack it into the props on your component, i.e., you "never" use {... props} inside your render() function, only when you pass the props down to another component. Use your unpacked props as normal this.props.x.

Using wget to recursively fetch a directory with arbitrary files in it

Wget 1.18 may work better, e.g., I got bitten by a version 1.12 bug where...

wget --recursive (...)

...only retrieves index.html instead of all files.

Workaround was to notice some 301 redirects and try the new location — given the new URL, wget got all the files in the directory.

Java, How do I get current index/key in "for each" loop

 
###################################################
###################################################
###################################################
AVOID THIS
###################################################
###################################################
###################################################

/*for (Song s: songList){
    System.out.println(s + "," + songList.indexOf(s); 
}*/

it is possible in linked list.

you have to make toString() in song class. if you don't it will print out reference of the song.

probably irrelevant for you by now. ^_^

git remove merge commit from history

To Just Remove a Merge Commit

If all you want to do is to remove a merge commit (2) so that it is like it never happened, the command is simply as follows

git rebase --onto <sha of 1> <sha of 2> <blue branch>

And now the purple branch isn't in the commit log of blue at all and you have two separate branches again. You can then squash the purple independently and do whatever other manipulations you want without the merge commit in the way.

Efficient way to remove keys with empty strings from a dict

Quick Answer (TL;DR)

Example01

### example01 -------------------

mydict  =   { "alpha":0,
              "bravo":"0",
              "charlie":"three",
              "delta":[],
              "echo":False,
              "foxy":"False",
              "golf":"",
              "hotel":"   ",                        
            }
newdict =   dict([(vkey, vdata) for vkey, vdata in mydict.iteritems() if(vdata) ])
print newdict

### result01 -------------------
result01 ='''
{'foxy': 'False', 'charlie': 'three', 'bravo': '0'}
'''

Detailed Answer

Problem

  • Context: Python 2.x
  • Scenario: Developer wishes modify a dictionary to exclude blank values
    • aka remove empty values from a dictionary
    • aka delete keys with blank values
    • aka filter dictionary for non-blank values over each key-value pair

Solution

  • example01 use python list-comprehension syntax with simple conditional to remove "empty" values

Pitfalls

  • example01 only operates on a copy of the original dictionary (does not modify in place)
  • example01 may produce unexpected results depending on what developer means by "empty"
    • Does developer mean to keep values that are falsy?
    • If the values in the dictionary are not gauranteed to be strings, developer may have unexpected data loss.
    • result01 shows that only three key-value pairs were preserved from the original set

Alternate example

  • example02 helps deal with potential pitfalls
  • The approach is to use a more precise definition of "empty" by changing the conditional.
  • Here we only want to filter out values that evaluate to blank strings.
  • Here we also use .strip() to filter out values that consist of only whitespace.

Example02

### example02 -------------------

mydict  =   { "alpha":0,
              "bravo":"0",
              "charlie":"three",
              "delta":[],
              "echo":False,
              "foxy":"False",
              "golf":"",
              "hotel":"   ",
            }
newdict =   dict([(vkey, vdata) for vkey, vdata in mydict.iteritems() if(str(vdata).strip()) ])
print newdict

### result02 -------------------
result02 ='''
{'alpha': 0,
  'bravo': '0', 
  'charlie': 'three', 
  'delta': [],
  'echo': False,
  'foxy': 'False'
  }
'''

See also

Hash table in JavaScript

Using the function above, you would do:

var myHash = new Hash('one',[1,10,5],'two', [2], 'three',[3,30,300]);

Of course, the following would also work:

var myHash = {}; // New object
myHash['one'] = [1,10,5];
myHash['two'] = [2];
myHash['three'] = [3, 30, 300];

since all objects in JavaScript are hash tables! It would, however, be harder to iterate over since using foreach(var item in object) would also get you all its functions, etc., but that might be enough depending on your needs.

How to start Activity in adapter?

callback from adapter to activity can be done using registering listener in form of interface: Make an interface:

      public MyInterface{
         public void  yourmethod(//incase needs parameters );
         }

In Adapter Let's Say MyAdapter:

    public MyAdapter extends BaseAdapter{
       private MyInterface listener;

    MyAdapter(Context context){
        try {
            this. listener = (( MyInterface ) context);
              } catch (ClassCastException e) {
               throw new ClassCastException("Activity must implement MyInterface");
          }

//do this where u need to fire listener l

          try {
                listener . yourmethod ();
            } catch (ClassCastException exception) {
               // do something
            }

      In Activity Implement your method:


         MyActivity extends AppCompatActivity implements MyInterface{

                yourmethod(){
                //do whatever you want
                     }
                     }

Python: 'ModuleNotFoundError' when trying to import module from imported package

For me when I created a file and saved it as python file, I was getting this error during importing. I had to create a filename with the type ".py" , like filename.py and then save it as a python file. post trying to import the file worked for me.

Changing route doesn't scroll to top in the new page

The problem is that your ngView retains the scroll position when it loads a new view. You can instruct $anchorScroll to "scroll the viewport after the view is updated" (the docs are a bit vague, but scrolling here means scrolling to the top of the new view).

The solution is to add autoscroll="true" to your ngView element:

<div class="ng-view" autoscroll="true"></div>

How can you profile a Python script?

There's also a statistical profiler called statprof. It's a sampling profiler, so it adds minimal overhead to your code and gives line-based (not just function-based) timings. It's more suited to soft real-time applications like games, but may be have less precision than cProfile.

The version in pypi is a bit old, so can install it with pip by specifying the git repository:

pip install git+git://github.com/bos/statprof.py@1a33eba91899afe17a8b752c6dfdec6f05dd0c01

You can run it like this:

import statprof

with statprof.profile():
    my_questionable_function()

See also https://stackoverflow.com/a/10333592/320036

Testing for empty or nil-value string

 
variable = id if variable.to_s.empty?

Understanding the Linux oom-killer's logs

Sum of total_vm is 847170 and sum of rss is 214726, these two values are counted in 4kB pages, which means when oom-killer was running, you had used 214726*4kB=858904kB physical memory and swap space.

Since your physical memory is 1GB and ~200MB was used for memory mapping, it's reasonable for invoking oom-killer when 858904kB was used.

rss for process 2603 is 181503, which means 181503*4KB=726012 rss, was equal to sum of anon-rss and file-rss.

[11686.043647] Killed process 2603 (flasherav) total-vm:1498536kB, anon-rss:721784kB, file-rss:4228kB

How to export MySQL database with triggers and procedures?

mysqldump will backup by default all the triggers but NOT the stored procedures/functions. There are 2 mysqldump parameters that control this behavior:

  • --routines – FALSE by default
  • --triggers – TRUE by default

so in mysqldump command , add --routines like :

mysqldump <other mysqldump options> --routines > outputfile.sql

See the MySQL documentation about mysqldump arguments.

INSTALL_FAILED_NO_MATCHING_ABIS when install apk

In my case, in a xamarin project, in visual studio error removed by selecting properties --> Android Options and check Use Share run Times and Use Fast Deployment, in some cases one of them enter image description here

Tools for making latex tables in R

The stargazer package is another good option. It supports objects from many commonly used functions and packages (lm, glm, svyreg, survival, pscl, AER), as well as from zelig. In addition to regression tables, it can also output summary statistics for data frames, or directly output the content of data frames.

How do I do multiple CASE WHEN conditions using SQL Server 2008?

Combining all conditions

select  a.* from tbl_Company a

where  a.Company_ID NOT IN (1,2)  

AND (   
        (0 = 
            CASE WHEN (@Fromdate = '' or @Todate='')
                THEN 0 
                ELSE 1  
            END
        )      -- if 0=0 true , if 0=1 fails (filter only when the fromdate and todate is present)
                OR
        (a.Created_Date between @Fromdate and @Todate )                 
    )

Reading images in python

you can try to use cv2 like this

import cv2

image= cv2.imread('image page')

cv2.imshow('image', image)

cv2.waitKey(0)

cv2.destroyAllWindows()

Get remote registry value

For remote registry you have to use .NET with powershell 2.0

$w32reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine',$computer1)
$keypath = 'SOFTWARE\Veritas\NetBackup\CurrentVersion'
$netbackup = $w32reg.OpenSubKey($keypath)
$NetbackupVersion1 = $netbackup.GetValue('PackageVersion')

Ansible: How to delete files and folders inside a directory?

Below code will delete the entire contents of artifact_path

- name: Clean artifact path
  file:
    state: absent
    path: "{{ artifact_path }}/"

Note: this will delete the directory too.

Spring Boot - Handle to Hibernate SessionFactory

Great work Andreas. I created a bean version so the SessionFactory could be autowired.

import javax.persistence.EntityManagerFactory;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;

....

@Autowired
private EntityManagerFactory entityManagerFactory;

@Bean
public SessionFactory getSessionFactory() {
    if (entityManagerFactory.unwrap(SessionFactory.class) == null) {
        throw new NullPointerException("factory is not a hibernate factory");
    }
    return entityManagerFactory.unwrap(SessionFactory.class);
}

Round button with text and icon in flutter

The way i usually do it is by embedding a Row inside the Raised button:

class Sendbutton extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return RaisedButton(
          onPressed: () {},
          color: Colors.black,
          textColor: Colors.white,
          child: Row(
            children: <Widget>[
              Text('Send'),
              Icon(Icons.send)
            ],
          ),

        );
      }
    }

JPA: difference between @JoinColumn and @PrimaryKeyJoinColumn?

I normally differentiate these two via this diagram:

Use PrimaryKeyJoinColumn

enter image description here

Use JoinColumn

enter image description here

Getting cursor position in Python

Prerequisites

Install Tkinter. I've included the win32api for as a Windows-only solution.

Script

#!/usr/bin/env python

"""Get the current mouse position."""

import logging
import sys

logging.basicConfig(format='%(asctime)s %(levelname)s %(message)s',
                    level=logging.DEBUG,
                    stream=sys.stdout)


def get_mouse_position():
    """
    Get the current position of the mouse.

    Returns
    -------
    dict :
        With keys 'x' and 'y'
    """
    mouse_position = None
    import sys
    if sys.platform in ['linux', 'linux2']:
        pass
    elif sys.platform == 'Windows':
        try:
            import win32api
        except ImportError:
            logging.info("win32api not installed")
            win32api = None
        if win32api is not None:
            x, y = win32api.GetCursorPos()
            mouse_position = {'x': x, 'y': y}
    elif sys.platform == 'Mac':
        pass
    else:
        try:
            import Tkinter  # Tkinter could be supported by all systems
        except ImportError:
            logging.info("Tkinter not installed")
            Tkinter = None
        if Tkinter is not None:
            p = Tkinter.Tk()
            x, y = p.winfo_pointerxy()
            mouse_position = {'x': x, 'y': y}
        print("sys.platform={platform} is unknown. Please report."
              .format(platform=sys.platform))
        print(sys.version)
    return mouse_position

print(get_mouse_position())

Window.open and pass parameters by post method

Instead of writing a form into the new window (which is tricky to get correct, with encoding of values in the HTML code), just open an empty window and post a form to it.

Example:

<form id="TheForm" method="post" action="test.asp" target="TheWindow">
<input type="hidden" name="something" value="something" />
<input type="hidden" name="more" value="something" />
<input type="hidden" name="other" value="something" />
</form>

<script type="text/javascript">
window.open('', 'TheWindow');
document.getElementById('TheForm').submit();
</script>

Edit:

To set the values in the form dynamically, you can do like this:

function openWindowWithPost(something, additional, misc) {
  var f = document.getElementById('TheForm');
  f.something.value = something;
  f.more.value = additional;
  f.other.value = misc;
  window.open('', 'TheWindow');
  f.submit();
}

To post the form you call the function with the values, like openWindowWithPost('a','b','c');.

Note: I varied the parameter names in relation to the form names to show that they don't have to be the same. Usually you would keep them similar to each other to make it simpler to track the values.

javascript: Disable Text Select

If you got a html page like this:

    <body
    onbeforecopy = "return false"
    ondragstart = "return false" 
    onselectstart = "return false" 
    oncontextmenu = "return false" 
    onselect = "document.selection.empty()" 
    oncopy = "document.selection.empty()">

There a simple way to disable all events:

document.write(document.body.innerHTML)

You got the html content and lost other things.

How to display Oracle schema size with SQL query?

If you just want to calculate the schema size without tablespace free space and indexes :

select
   sum(bytes)/1024/1024 as size_in_mega,
   segment_type
from
   dba_segments
where
   owner='<schema's owner>'
group by
   segment_type;

For all schemas

select
   sum(bytes)/1024/1024 as size_in_mega, owner
from
   dba_segments
group by
  owner;

How do I get extra data from intent on Android?

Getting Different Types of Extra from Intent

To access data from Intent you should know two things.

  • KEY
  • DataType of your data.

There are different methods in Intent class to extract different kind of data types. It looks like this

getIntent().XXXX(KEY) or intent.XXX(KEY);


So if you know the datatype of your varibale which you set in otherActivity you can use the respective method.

Example to retrieve String in your Activity from Intent

String profileName = getIntent().getStringExtra("SomeKey");

List of different variants of methods for different dataType

You can see the list of available methods in Official Documentation of Intent.

How do I set Tomcat Manager Application User Name and Password for NetBeans?

You will find the tomcat-users.xml in \Users\<Name>\AppData\Roaming\Netbeans\. It exists at least twice on your machine, depending on the number of Tomcat installations you have.

Plotting two variables as lines using ggplot2 on the same graph

You need the data to be in "tall" format instead of "wide" for ggplot2. "wide" means having an observation per row with each variable as a different column (like you have now). You need to convert it to a "tall" format where you have a column that tells you the name of the variable and another column that tells you the value of the variable. The process of passing from wide to tall is usually called "melting". You can use tidyr::gather to melt your data frame:

library(ggplot2)
library(tidyr)

test_data <-
  data.frame(
    var0 = 100 + c(0, cumsum(runif(49, -20, 20))),
    var1 = 150 + c(0, cumsum(runif(49, -10, 10))),
    date = seq(as.Date("2002-01-01"), by="1 month", length.out=100)
  )
test_data %>%
    gather(key,value, var0, var1) %>%
    ggplot(aes(x=date, y=value, colour=key)) +
    geom_line()

multiple series ggplot2

Just to be clear the data that ggplot is consuming after piping it via gather looks like this: 

date        key     value
2002-01-01  var0    100.00000
2002-02-01  var0    115.16388 
...
2007-11-01  var1    114.86302
2007-12-01  var1    119.30996

Git merge develop into feature branch outputs "Already up-to-date" while it's not

You should first pull the changes from the develop branch and only then merge them to your branch:

git checkout develop 
git pull 
git checkout branch-x
git rebase develop

Or, when on branch-x:

git fetch && git rebase origin/develop

I have an alias that saves me a lot of time. Add to your ~/.gitconfig:

[alias]
    fr = "!f() { git fetch && git rebase origin/"$1"; }; f"

Now, all that you have to do is:

git fr develop

How to get just numeric part of CSS property with jQuery?

For improving accepted answer use this:

Number($(this).css('marginBottom').replace(/[^-\d\.]/g, ''));

How do I detect whether 32-bit Java is installed on x64 Windows, only looking at the filesystem and registry?

just write "java -d64 -version" or d32 and if you have It installed it will give a response with current version installed

Is a new line = \n OR \r\n?

The given answer is far from complete. In fact, it is so far from complete that it tends to lead the reader to believe that this answer is OS dependent when it isn't. It also isn't something which is programming language dependent (as some commentators have suggested). I'm going to add more information in order to make this more clear. First, lets give the list of current new line variations (as in, what they've been since 1999):

  • \r\n is only used on Windows Notepad, the DOS command line, most of the Windows API and in some (older) Windows apps.
  • \n is used for all other systems, applications and the Internet.

You'll notice that I've put most Windows apps in the \n group which may be slightly controversial but before you disagree with this statement, please grab a UNIX formatted text file and try it in 10 web friendly Windows applications of your choice (which aren't listed in my exceptions above). What percentage of them handled it just fine? You'll find that they (practically) all implement auto detection of line endings or just use \n because, while Windows may use \r\n, the Internet uses \n. Therefore, it is best practice for applications to use \n alone if you want your output to be Internet friendly.

PHP also defines a newline character called PHP_EOL. This constant is set to the OS specific newline string for the machine PHP is running on (\r\n for Windows and \n for everything else). This constant is not very useful for webpages and should be avoided for HTML output or for writing most text to files. It becomes VERY useful when we move to command line output from PHP applications because it will allow your application to output to a terminal Window in a consistent manner across all supported OSes.

If you want your PHP applications to work from any server they are placed on, the two biggest things to remember are that you should always just use \n unless it is terminal output (in which case you use PHP_EOL) and you should also ALWAYS use / for your path separator (not \).

The even longer explanation:

An application may choose to use whatever line endings it likes regardless of the default OS line ending style. If I want my text editor to print a newline every time it encounters a period that is no harder than using the \n to represent a newline because I'm interpreting the text as I display it anyway. IOW, I'm fiddling around with measuring the width of each character so it knows where to display the next so it is very simple to add a statement saying that if the current char is a period then perform a newline action (or if it is a \n then display a period).

Aside from the null terminator, no character code is sacred and when you write a text editor or viewer you are in charge of translating the bits in your file into glyphs (or carriage returns) on the screen. The only thing that distinguishes a control character such as the newline from other characters is that most font sets don't include them (meaning they don't have a visual representation available).

That being said, if you are working at a higher level of abstraction then you probably aren't making your own textbox controls. If this is the case then you're stuck with whatever line ending that control makes available to you. Even in this case it is a simple matter to automatically detect the line ending style of any string and make the conversion before you load your text into the control and then undo it when you read from that control. Meaning, that if you're a desktop application dev and your application doesn't recognize \n as a newline then it isn't a very friendly application and you really have no excuse because it isn't hard to make it the right way. It also means that whomever wrote Notepad should be ashamed of himself because it really is very easy to do much better and so many people suffer through using it every day.