Compile Time Constant

[Harikrishna Gorrepati]

Hi, Why I am getting an error at Line #7 . If I replace Line 3 and Line 4 with final int b = 2; I don't get error. This is called Compile Time constant..what is the logic behind this.

public class P336_switch_break01_CTConstant_Ask {
    public static void main(String[] args) {
	final int b;
	b = 2;
	int x = 0;
	switch (x) {
	case b: // case expressions must be constant expressions
	    System.out.println("1");
	    break;
	}
    }
}

[Ankit Garg]

Read this compile time constants tutorial...

[Harikrishna Gorrepati]

Hi Ankit, I raised this question based on your written tutorial. How the compiler treats the following 2 ways of declaring a variable. I fee both are exactly same but compiler thinks they are different..What's happening..

final int b;
b= 2;

and

final int b = 2;

[Simone Aiello]

....

[Simone Aiello]

final int b;
b= 4;

is like write

 
final int b;
if(true)b= 4;

the compiler doesn't ever know b will be initialized to 4, even if it's obvious that it occurs...

[Henry Wong]

I wrote an explanation a while back...

https://coderanch.com/t/454384/java/java/compile-time-constant

Henry