Compile Once - Run Anywhere

In the previous example, I compiled and ran prog11 on a Solaris machine. Java is designed to be platform independent or portable. To show that it could be run on a different platform, I copied the prog11.class file to a Windows 7 machine in binary mode. Then I ran it there as follows:

 

C:\Java>dir

Volume in drive C is System

Volume Serial Number is B068-444A

 

Directory of C:\Java

 

04/29/2013  05:37 PM    <DIR>          .

04/29/2013  05:37 PM    <DIR>          ..

04/29/2013  05:36 PM               717 prog11.class

               1 File(s)            717 bytes

               2 Dir(s)  204,152,512,512 bytes free

 

C:\Java>java prog11

a = 100

b = 100

 

C:\Java>

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How to Copy a long Java Variable Into an int

You might think that you could copy a long variable into an int variable like this:

 

Solaris > cat prog10.java

public class prog10

{

public static void main (String args[])

  {

  int a;

  long b = 100;

  a = b;

  System.out.println ("a = " + a);

  System.out.println ("b = " + b);

  }

}

Solaris >

 

… but you get a compilation error if you try:

 

Solaris > javac prog10.java

prog10.java:7: possible loss of precision

found   : long

required: int

  a = b;

      ^

1 error

Solaris >

 

You have to do it like this instead:

 

Solaris > cat prog11.java

public class prog11

{

public static void main (String args[])

  {

  int a;

  long b = 100;

  a = (int) b;

  System.out.println ("a = " + a);

  System.out.println ("b = " + b);

  }

}

Solaris > javac prog11.java

Solaris > java prog11

a = 100

b = 100

Solaris >

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