Java variable scope in and outside loop

Question

I wrote this code in an online java test recently. It was inside a method that was set to return an integer. I got an error message something like "variable a has no value assigned to it". I find this odd because the forloop must have access to the methods variable and the assignments inside of the loop must be registered right?

int a;
for(int i=1;i<5;i++){
    a = i;} 
return a;

I did assume that the method would return the integer 5.

This is only a question regarding scope of the variable a. I know that the code makes no sense.

Code inside a `for` loop is treated by the compiler as code that _might or might not_ be run. So the compiler sees a path by which `a` would not have been initialised before you try and return it. — khelwood, Aug 25 '20 at 13:44
The compiler doesn't know that the loop will execute at least once. — Andy Turner, Aug 25 '20 at 13:44
See [Why does the Java compiler not understand this variable is always initialized?](https://stackoverflow.com/q/13235559/3890632) — khelwood, Aug 25 '20 at 13:46
@klutt I was looking for one that was about a loop. Close enough, I think. — khelwood, Aug 25 '20 at 13:49
@khelwood Yes, it's definitely close enough. Exactly the same principle. — klutt, Aug 25 '20 at 13:50

score 0 · Accepted Answer · answered Aug 25 '20 at 13:49

0

You can try below code , that will help you. Initialisation is mandatory for any variable to return or hold any value.

class a{
    public static void main(String[] args) {
        System.out.println(test());
    }
    public static int test(){
        int a = 0;
        for(int i=1;i<5;i++){
            a = i;}
        return a;
    }
}

answered Aug 25 '20 at 13:49

Ronak R

79
3

1

OP does not ask how to avoid it, but why the compiler complains at all. – klutt Aug 25 '20 at 13:50

Java variable scope in and outside loop

1 Answers1