How do I track a parameter inside a method?

Question

basically i need to track what the method does with the parameter, i can't modify the function to be tracked.

Ultimately what I'm trying to do is visually represent what the method does with the parameter.

I know java passes by value, so I'm having a hard time finding a workaround without modifying the method itself.

For example:

public void foo(int x){
   x+=10;
}

If I call it like this:

foo(2);

I need to be able to draw 2 rectangles, one with 2 width and one with 12.

I'd really appreciate some help, thanks in advance!

Answer 1

Java passes parameters by value, so the instruction inside the method

x += 10;

has no effect whatsoever on what was passed in, ie

int i = 2;
foo(i);
System.out.println(i); // 2

You would have to perform static code analysis to show what happens inside the method, noting that nothing actually happens to a variable passed in.