return key word in a void method in java?

Question

Hi all. Looking a path finding tutorial here (http://www.cokeandcode.com/pathfinding) which i was linked to from SO :) good work people.

Working in integrating the code into my game, and i noticed a "return;" line inside a void method. class is PathTest on website, line 130.

I know im a novice at java, but can anyone tell me why its there? As far as I knew, return inside a void method isn't allowed.

Thanks in advance

Rel

Answer 1

I just exits the function at that point. Code after it has returned is not run.

eg.

public void test(int n)
{
    if(n == 1)
    {
        return; 
    }
    else if(n == 2)
    {
        doStuff();
        return;
    }
    doOtherStuff();
}

Note that the compiler is smart enough to tell you some code cannot be reached:

if(n == 3)
{
    return;
    youWillGetAnError();
}

Answer 2

You can have return in a void method, you just can return anything. Some people always explicitly end void methods with a return statement, but it's not mandatory. It can be used to leave a function early, though:

void someFunct(int arg)
{
    if (arg == 0)
    {
        //Leave because this is a bad value
        return;
    }
    //Otherwise, do something
}

Answer 3

The Java language specification says you can have return with no expression if your method returns void.

Answer 4

It functions the same as a return for function with a specified parameter, except it returns nothing, as there is nothing to return and control is passed back to the calling method.

Answer 5

It exits the function and returns nothing.

Something like return 1; would be incorrect since it returns integer 1.

Answer 6

The keyword simply pops a frame from the call stack returning the control to the line following the function call.