Local Variable Initialization Java

Question

public class LocalVariables {

    static public void main(String args[]){

        int var;

        if(args.length > 0){
            var = 10;

        }

        else{
            var = 20;
        }
        System.out.println(var);
    }

}

Here if I remove else part it's showing compilation error as:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
The local variable var may not have been initialized

Explain how the local variable value is initialized if I use else part.

shouldn't this be `public static void main` and not `static public void main`? — px06, Dec 02 '16 at 09:23
@px06 literally no difference. You can declare the modifiers in whatever order you like. — Andy Turner, Dec 02 '16 at 09:24
Well, without the else, what would be the value of `var` when `args.length != 10`? Where do you think that value comes from? — yshavit, Dec 02 '16 at 09:24
@AndyTurner right okay, other than that I don't see a problem with it — px06, Dec 02 '16 at 09:24
If you remove the `else` clause then `var` might not be assigned any value before you try and print it out. Pretty clear error message. What part is giving you difficulty? — khelwood, Dec 02 '16 at 09:24
@px06 read the question. OP says there's a problem if he removes the `else`. — Andy Turner, Dec 02 '16 at 09:24
How ELSE part is ensuring initialization of variable? There's no problem with IF condition but if I remove ELSE it's throwing error. — vny uppara, Dec 02 '16 at 10:02

score 2 · Accepted Answer · answered Dec 02 '16 at 09:28

2

Look at it like this what happens when the if condition in your code is not met? The reason you would be getting an error saying :

The local variable var may not have been initialized

is because if the condition is false you really don't have var initialised, do you?

On the other hand else was serving the purpose of ensuring the initialization in the existing code for you.

answered Dec 02 '16 at 09:28

Naman

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When the condition of IF is not met the output is 20 . Tell me how else part is ensuring initialization why not if part? – vny uppara Dec 02 '16 at 09:53
once you remove `else` part and your args.length `< =0`. Could you tell me what would be the value of `var` in your code? – Naman Dec 02 '16 at 11:20

score 1 · Answer 2 · answered Dec 02 '16 at 09:28

1

if you remove else block, what would be the value of var if(args.length<0) ? The compiler doesn't know that. So it shows you error. Either you have to initialize the var during declaration or you need to initialize in both if and else block.

answered Dec 02 '16 at 09:28

Habin

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`if (args.length <= 0)`. – Andy Turner Dec 02 '16 at 09:37

score -1 · Answer 3 · answered Dec 02 '16 at 09:31

-1

When executing main method, surely you do not provide args argument. So args.length > 0 returns false.

answered Dec 02 '16 at 09:31

sk001

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did you try running the code? – Naman Dec 02 '16 at 09:32
This answer has nothing to do with OP's problem. OP is asking about a compilation problem, not a runtime problem. – Andy Turner Dec 02 '16 at 09:38

Local Variable Initialization Java

3 Answers3