What happens after a method is called in Java

Question

This looks like a silly question but I found it is hard to get it right. I have asked different people but couldn't get an ideal answer.

I want to know what happens after we call a normal method in Java (Provided in a single threaded environment).

My understanding is that:

1. All current stack variables are poped-up and stored somewhere (where?)
2. The current method call halts
3. The arguments of the newly called method are pushed to the stack
4. The method code runs
5. After the method finished running, the stack is again emptied and the old stack contents is again restored. (What happened if the function returns a value?).
6. Code continues with the calling method.

This is a very incomplete and possibly wrong answer. Can someone provide a more detailed description?

Many thanks.

Answer 1

No, that's actually fairly accurate:

1) current stack variables remain on the stack

2) The current method pauses

3) The arguments of the newly called method are pushed to the stack

4) The method code runs

5) After the method finished running, we pop the stack. The called method's stack variables are no longer valid - they no longer "exist" at this point.

6) We pass the return value (if any) to the caller

7) Code continues with the calling method. All it's stack variables remain intact.

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ADDENDUM:

@Kevin -

• Conceptually, I think you got it just about right. I clarified a few points, I hope that helps.

• David Wallace's link is very good if you want to go in depth on how the JVM implements "method calling".

• Here is a good overview on how "a stack" works. Any stack, calling any subroutine - not just Java: http://en.wikipedia.org/wiki/Call_stack

• Finally, Marko Topolnik is correct. "The reality" is almost always complex enough that it doesn't lend itself to a simple, one-size-fits all answer. But I definitely think your understanding is good. At least at the 10,000 foot level.

IMHO...