Java return Issue

Question

1. What is the effect of not catching the value of the method that returns a value?

2. Does it develop complications like memory issues if the return value was not caught.

Example code snippets:

//reference types
public Object[] thismethodreturnsvalue(){
   return new Object[]{new Object(),new Object(),new Object()};
}

//primitive types
public int thismethodreturnsint(){
   return -1;
}

public static void main(String a[]){
   thismethodreturnsvalue();
   thismethodreturnsint();
}

Answer 1

1. What is the effect of not catching the value of the method that returns a value?

No effect really.

The return value will be computed, and if it was created on the heap (as in your first example), it will be eligible for garbage collection right away.

In your second example, the return value will end up on the stack and will simply be discarded after the method has returned.

2. Does it develop complications like memory issues if the return value was not caught.

No, not really. As I said above, it will be garbage collected.

Here is a bytecode dump of what happens at the call site:

public class Test {

    public static int testMethod() {
        return 5;
    }

    public static void main(String[] args) {
        testMethod();
    }
}

... corresponding bytecode:

public static int testMethod();
  Code:
   0:   iconst_5
   1:   ireturn


public static void main(java.lang.String[]);
  Code:
   0:   invokestatic    #2;
   3:   pop                 // return value popped immediately.
   4:   return
}