variable not initialed

[Vijay Bhuruk]

  class Test{

          public static void main(String args[]) 
     
    {  
        int a = 20;
        int b;
 
    if(a>9)
     {
       b=8;
      }
   System.out.println(b);

    }
}  

when i compile,get error. Error: variable b might not have been initialised.


only way to clear error is initialise b.(tested for b=4)

but when i tried below code,where i have not initialised variable b,it works too.

  class Test{

          public static void main(String arg[]) 
     
    {  
        final int a = 20;          // change
        int b;
 
    if(a>9)
     {
       b=8;
      }
   System.out.println(b);

    }
}  

why?

[James Tharakan]

class Test{

          public static void main(String arg[]) 
     
    {  
        final int a = 0;          // change
        int b;
 
    if(a>9)
     {
       b=8;
      }
   System.out.println(b);

    }
}  

Try this it will still give error...

The reason the first code gives error is.....
"a" is non-final varible means it can change its value later....
And the compiler know that if the if condition fails "b" will not be initilaized.So error says "using before initilzing"

In the second case "a" in final and compiler can be sure that the value will not change and the "b" variable WILL be initialized

[Vijay Bhuruk]

Thanks James.

[harilal ithikkat]

James really cool answer.....................

[Monu Tripathi]

Just adding my 25 paise..

If interested in this idiosyncrasy of the Java compiler, you might want to read JLS Chapter 16 - Definite Assignment which addresses this area.