Scala write string to file in one statement

Question

For reading files in Scala  there is   Source fromFile  file txt   mkString   Is there an equivalent and concise way to write a string to file   Most languages support something like that  My favorite is Groovy   def f   new File  file txt      Read def s   f text    Write f text    file contents    I d like to use the code for programs ranging from a single line to a short page of code  Having to use your own library doesn t make sense here  I expect a modern language to let me write something to a file conveniently    There are posts similar to this  but they don t answer my exact question or are focused on older Scala versions   For example    Read entire file in Scala  How to write to a file in Scala

User · Answer

Here s the modern  safe one liner  java nio file Files write java nio file Paths get  quot  tmp output txt quot     quot Hello world quot  getBytes      nio is a modern IO library shipped by default with the JDK 9  so no imports or dependencies required

User · Answer

UPDATE  I have since created a more effective solution upon which I have elaborated here  https   stackoverflow com a 34277491 501113  I find myself working more and more in the Scala Worksheet within the Scala IDE for Eclipse  and I believe there is something equivalent in IntelliJ IDEA   Anyway  I need to be able to do a one-liner to output some of the contents as I get the  Output exceeds cutoff limit   message if I am doing anything significant  especially with the Scala collections   I came up with a one-liner I insert into the top of each new Scala Worksheet to simplify this  and so I don t have to do the whole external library import exercise for a very simple need   If you are a stickler and notice that it is technically two lines  it s only to make it more readable in this forum  It is a single line in my Scala Worksheet   def printToFile content  String  location  String    C  Users jtdoe Desktop WorkSheet txt       Some new java io PrintWriter location   foreach f   gt  try f write content  finally f close     And the usage is simply     printToFile  A fancy test string ncontaining newlines nOMG  n     This allows me to optionally provide the file name should I want to have additional files beyond the default  which completely overwrites the file each time the method is called    So  the second usage is simply     printToFile  A fancy test string ncontaining newlines nOMG  n    C  Users jtdoe Desktop WorkSheet txt     Enjoy

User · Answer

os-lib is the best modern way to write to a file  as mentioned here  Here s how to write  quot hello quot  to the file txt file  os write os pwd  quot file txt quot    quot hello quot    os-lib hides the Java ugliness and complexity  it uses the Java libs under the hood  so it s just as performant    See here for more info about using the lib

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This is concise enough  I guess   scala gt  import java io   import java io    scala gt  val w   new BufferedWriter new FileWriter  output txt    w  java io BufferedWriter   java io BufferedWriter 44ba4f  scala gt  w write  Alice r nBob r nCharlie r n    scala gt  w close

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It is strange that no one had suggested NIO 2 operations  available since Java 7    import java nio file  Paths  Files  import java nio charset StandardCharsets  Files write Paths get  file txt     file contents  getBytes StandardCharsets UTF 8     I think this is by far the simplest and easiest and most idiomatic way  and it does not need any dependencies sans Java itself

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I know it s not one line  but it solves the safety issues as far as I can tell      This possibly creates a FileWriter  but maybe not val writer   Try new FileWriter new File  filename        If it did  we use it to write the data and return it again    If it didn t we skip the map and print the exception and return the original  just in-case it was actually  write   that failed    Then we close the file writer map w   gt   w write  data    w   recoverWith case e   gt   e printStackTrace    writer   map   close    If you didn t care about the exception handling then you can write  writer map w   gt   w writer  data    w   recoverWith case     gt  writer  map   close

User · Answer

A concise one line   import java io PrintWriter new PrintWriter  filename     write  file contents    close

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A micro library I wrote  https   github com pathikrit better-files  file write  Hi      or  file  lt  lt   Hi

User · Answer

Use ammonite ops library  The syntax is very minimal  but the breadth of the library is almost as wide as what one would expect from attempting such a task in a shell scripting language like bash  On the page I linked to  it shows numerous operations one can do with the library  but to answer this question  this is an example of writing to a file import ammonite ops   write pwd   quot file txt quot    quot file contents quot

User · Answer

Here is a concise one-liner using reflect io file  this works with Scala 2 12   reflect io File  filename   writeAll  hello world     Alternatively  if you want to use the Java libraries you can do this hack   Some new PrintWriter  filename    foreach p   gt  p write  hello world    p close

User · Answer

You can easily use Apache File Utils  Look at function writeStringToFile  We use this library in our projects

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You can do this with a mix of Java and Scala libraries  You will have full control over the character encoding  But unfortunately  the file handles will not be closed properly    scala gt  import java io ByteArrayInputStream import java io ByteArrayInputStream  scala gt  import java io FileOutputStream import java io FileOutputStream  scala gt  BasicIO transferFully new ByteArrayInputStream  test  getBytes  UTF-8     new FileOutputStream  test txt

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One also has this format  which is both concise and the underlying library is beautifully written  see the source code    import scalax io Codec import scalax io JavaConverters    implicit val codec   Codec UTF8  new java io File  hi-file txt   asOutput write  I m a hi file      Really

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If you like Groovy syntax  you can use the Pimp-My-Library design pattern to bring it to Scala   import java io   import scala io    class RichFile  file  File        def text   Source fromFile  file   Codec UTF8  mkString    def text    s  String         val out   new PrintWriter  file    UTF-8       try  out print  s         finally  out close          object RichFile      implicit def enrichFile  file  File     new RichFile  file        It will work as expected   scala gt  import RichFile enrichFile import RichFile enrichFile  scala gt  val f   new File   tmp example txt   f  java io File    tmp example txt  scala gt  f text    hello world   scala gt  f text res1  String     hello world

User · Answer

import sys process    echo hello world    gt  new java io File   tmp example txt

User · Answer

Through the magic of the semicolon  you can make anything you like a one-liner   import java io PrintWriter import java nio file Files import java nio file Paths import java nio charset StandardCharsets import java nio file StandardOpenOption val outfile   java io File createTempFile         getPath val outstream   new PrintWriter Files newBufferedWriter Paths get outfile      StandardCharsets UTF 8     StandardOpenOption WRITE    outstream println  content    outstream flush    outstream close

[scala] Scala: write string to file in one statement

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