Getting Keyboard Input

Question

How do I get simple keyboard input  an integer  from the user in the console in Java  I accomplished this using the java io   stuff  but it says it is deprecated   How should I do it now

User · Answer

In java we can read input values in 6 ways   Scanner Class BufferedReader Console class Command line AWT  String  GUI System properties    Scanner class  present in java util    package and it has many methods  based your input types you can utilize those methods  a  nextInt   b  nextLong   c  nextFloat   d  nextDouble   e  next   f  nextLine    etc      import java util Scanner  public class MyClass       public static void main String args              Scanner sc   new Scanner System in           System out println  quot Enter a   quot            int a   sc nextInt            System out println  quot Enter b   quot            int b   sc nextInt                     int c   a   b          System out println  quot Result   quot  c              BufferedReader class  present in java io    package  amp  it has many method  to read the value from the keyboard use  quot readLine   quot    this method reading one line at a time    import java io BufferedReader  import java io    public class MyClass       public static void main String args    throws IOException          BufferedReader br   new BufferedReader new BufferedReader new InputStreamReader System in             System out println  quot Enter a   quot            int a   Integer parseInt br readLine             System out println  quot Enter b   quot            int b   Integer parseInt br readLine                      int c   a   b          System out println  quot Result   quot  c

User · Answer

You can use Scanner class   Import first     import java util Scanner    Then you use like this   Scanner keyboard   new Scanner System in   System out println  enter an integer    int myint   keyboard nextInt      Side note   If you are using nextInt   with nextLine   you probably could have some trouble cause nextInt   does not read the last newline character of input and so nextLine   then is not gonna to be executed with desired behaviour  Read more in how to solve it in this previous question Skipping nextLine using nextInt

User · Answer

If you have Java 6  You should have  btw  or higher  then simply do this     Console console   System console     String str   console readLine  Please enter the xxxx         Please remember to do     import java io Console    Thats it

User · Answer

import java util Scanner    import the framework   Scanner input   new Scanner System in     opens a scanner  keyboard System out print  Enter a number        prompt the user int myInt   input nextInt      store the input from the user   Let me know if you have any questions  Fairly self-explanatory  I commented the code so you can read it

User · Answer

You can also make it with BufferedReader if you want to validate user input  like this   import java io BufferedReader  import java io InputStreamReader   class Areas       public static void main String args             float PI   3 1416f          int r 0          String rad    We re going to read all user s text into a String and we try to convert it later         BufferedReader br   new BufferedReader new InputStreamReader System in      Here you declare your BufferedReader object and instance it          System out println  Radius             try              rad   br readLine      We read from user s input             r   Integer parseInt rad     We validate if  rad  is an integer  if so we skip catch call and continue on the next line  otherwise  we go to it  catch call               System out println  Circle area is      PI r r     Perimeter     PI 2 r     If all was right  we print this                   catch Exception e               System out println  Write an integer number      This is what user will see if he she write other thing that is not an integer             Areas a   new Areas      We call this class again  so user can try it again              You can also print exception in case you want to see it as follows                e printStackTrace                        Because Scanner class won t allow you to do it  or not that easy     And to validate you use  try-catch  calls

User · Answer

You can use Scanner class  To Read from Keyboard  Standard Input  You can use Scanner is a class in java util package   Scanner package used for obtaining the input of the primitive types like int  double etc  and strings  It is the easiest way to read input in a Java program  though not very efficient    To create an object of Scanner class  we usually pass the predefined object System in  which represents the standard input stream  Keyboard     For example  this code allows a user to read a number from System in    Scanner sc   new Scanner System in        int i   sc nextInt      Some Public methods in Scanner class    hasNext    Returns true if this scanner has another token in its input  nextInt   Scans the next token of the input as an int  nextFloat   Scans the next token of the input as a float  nextLine   Advances this scanner past the current line and returns the input that was skipped   nextDouble   Scans the next token of the input as a double  close   Closes this scanner    For more details of Public methods in Scanner class   Example -  import java util Scanner                         importing class  class ScannerTest     public static void main String args          Scanner sc   new Scanner System in            Scanner object      System out println  Enter your rollno        int rollno   sc nextInt        System out println  Enter your name        String name   sc next        System out println  Enter your fee        double fee   sc nextDouble        System out println  Rollno     rollno     name     name     fee     fee       sc close                                    closing object

User · Answer

Add line   import java util Scanner    Then create an object of Scanner class   Scanner s   new Scanner System in     Now you can call any time   int a   Integer parseInt s nextLine       This will store integer value from your keyboard

User · Answer

You can use Scanner to get the next line and do whatever you need to do with the line entered  You can also use JOptionPane to popup a dialog asking for inputs   Scanner example   Scanner input   new Scanner System in   System out print  Enter something  gt      String inputString   input nextLine    System out print  You entered       System out println inputString     JOptionPane example   String input   JOptionPane showInputDialog null        Enter some text     JOptionPane showMessageDialog null  You entered    input     You will need these imports   import java util Scanner  import javax swing JOptionPane    A complete Java class of the above  import java util Scanner  import javax swing JOptionPane  public class GetInputs      public static void main String args               Scanner example         Scanner input   new Scanner System in           System out print  Enter something  gt              String inputString   input nextLine            System out print  You entered               System out println inputString              JOptionPane example         String input   JOptionPane showInputDialog null           Enter some text             JOptionPane showMessageDialog null  You entered    input

User · Answer

You can use Scanner class like this     import java util Scanner   public class Main      public static void main String args          Scanner scan  new Scanner System in          For string      String text  scan nextLine         System out println text          for int      int num  scan nextInt         System out println num

User · Answer

Import  import java util Scanner   Define your variables  String name  int age   Define your scanner  Scanner scan   new Scanner System in    If you want to type     Text  name   scan nextLine    Integer  age   scan nextInt      Close scanner if no longer needed  scan close

[java] Getting Keyboard Input

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