How to read integer value from the standard input in Java

Question

What class can I use for reading an integer variable in Java

User · Answer

You can use java util Scanner  API    import java util Scanner          Scanner in   new Scanner System in   int num   in nextInt      It can also tokenize input with regular expression  etc  The API has examples and there are many others in this site  e g  How do I keep a scanner from throwing exceptions when the wrong type is entered

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Second answer above is the most simple one   int n   Integer parseInt System console   readLine       The question is  How to read from standard input    A console is a device typically associated to the keyboard and display from which a program is launched   You may wish to test if no Java console device is available  e g  Java VM not started from a command line or  the standard input and output streams are redirected   Console cons  if   cons   System console       null        System err println  Unable to obtain console                Using console is a simple way to input numbers  Combined with parseInt   Double   etc   s   cons readLine  Enter a int      int i   Integer parseInt s        s   cons readLine  Enter a double      double d   Double parseDouble s

User · Answer

If you are using Java 6  you can use the following oneliner to read an integer from console   int n   Integer parseInt System console   readLine

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This causes headaches so I updated a solution that will run using the most common hardware and software tools available to users in December 2014  Please note that the JDK SDK JRE Netbeans and their subsequent classes  template libraries compilers  editors and debuggerz are free    This program was tested with Java v8 u25  It was written and built using Netbeans IDE 8 0 2  JDK 1 8  OS is win8 1  apologies  and browser is Chrome  double-apologies   - meant to assist UNIX-cmd-line OG s deal with modern GUI-Web-based IDEs at ZERO COST - because information  and IDEs  should always be free  By Tapper7  For Everyone   code block            package modchk    Netbeans requirement      import java util Scanner        import java io    is not needed Netbeans automatically includes it                 public class Modchk           public static void main String   args               int input1              int input2                 Explicity define the purpose of the  exe to user              System out println  Modchk by Tapper7  Tests IOStream and basic bool modulo fxn  n                 Commented and coded for C C   programmers new to Java n                   create an object that reads integers              Scanner Cin   new Scanner System in                   the following will throw   if you don t do you what it tells you or if                int entered    ArrayIndex-out-of-bounds for your system   - 2 1e9             System out println  Enter an integer wiseguy                  input1   Cin nextInt      this command emulates  cin  gt  gt  input1                  I test like Ernie Banks played hardball   Let s play two               System out println  Enter another integer   anyday now                  input2   Cin nextInt                    debug the scanner and istream              System out println  the 1st N entered by the user was     input1               System out println  the 2nd N entered by the user was     input2                   do maths  on vars to make sure they are of use to me              System out println  modchk for     input1               if 2   input1    0                   System out print input1     is even n       lt ---same output effect as   println                  else                  System out println input1     is odd                   endif input1                one mo   gain  as in istream dbg chk above              System out println  modchk for     input2               if 2   input2    0                   System out print input2     is even n                     else                  System out println input2     is odd                   endif input2            end main        end Modchk

User · Answer

Here I am providing 2 examples to read integer value from the standard input  Example 1  import java util Scanner  public class Maxof2      public static void main String args                 taking value as command line argument          Scanner in   new Scanner System in           System out printf  Enter i Value              int i   in nextInt           System out printf  Enter j Value              int j   in nextInt           if i  gt  j             System out println i  i is greater than   j          else            System out println j   is greater than   i             Example 2  public class ReadandWritewhateveryoutype      public static void main String args    throws java lang Exception     System out printf  This Program is used to Read and Write what ever you type  nType  quit  to Exit at any Moment n n        java io BufferedReader r   new java io BufferedReader  new java io InputStreamReader  System in         String hi       while    hi r readLine    startsWith  quit   System out printf   nYou have typed   s  n  hi               I prefer the First Example  it s easy and quite understandable  You can compile and run the JAVA programs online at this website  http   ideone com

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Check this one   public static void main String   args        String input   null      int number   0      try           BufferedReader bufferedReader   new BufferedReader new InputStreamReader System in            input   bufferedReader readLine            number   Integer parseInt input         catch  NumberFormatException ex           System out println  Not a number            catch  IOException e            e printStackTrace

User · Answer

check this one   import java io    public class UserInputInteger           public static void main String args   throws IOException                   InputStreamReader read   new InputStreamReader System in           BufferedReader in   new BufferedReader read           int number                  System out println  Enter the number                    number   Integer parseInt in readLine

[java] How to read integer value from the standard input in Java

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