Help with printing simple things.

[Aimforthehead]

So I have this simple code with various methods and I need to determine the state of the object after each line.

public class Trace {
	private int a;
	
	public Trace(int a){
		this.a = a;
	}

	public Trace(int a, int b) {
		this.a = a * b;
	}
	
	public int joe(int a) {
		return this.a += a;
	}
	
	public int liz(int a ) {
		return this.a *= a;
	}

	public static void main(String[] args) {
		Trace bee = new Trace(1);
		Trace zoo = new Trace(3);
		bee.joe(2);
		bee.liz(2);
		zoo = bee;
		bee = new Trace(2,4);
		zoo.joe(bee.liz(2));
		bee = zoo;
		bee.liz(3);
		
	}
	
}

For example after line 22, bee refers to Trace in which a = 1, and zoo refers to Trace in which a = 3. Right? Or am I wording this wrong?
How would I print these values for each line to test if my predictions are correct?

I try printing bee and zoo but that doesn't seem to work...

ACTUALLY,
I managed to print out each step by using System.out.println(bee.a); and System.out.println(zoo.a);
But I am confused as to how I got each value.
Can someone explain why putting in bee.joe(2); gives an output of 3? Maybe I can be able to get it from there.

[doWhile]

Can someone explain why putting in bee.joe(2); gives an output of 3?

Take a pen and paper and write out each step the program performs one by one. You create an object with a variable a value of 1, you then call the method joe - which adds the parameter 2 to a (this equals 3) and sets the value of a to this result, and finally return the result.

[Aimforthehead]

Well, I did that first and came out with 5. I thought
Trace zoo = new Trace(3); would give a the value of 3, then in joe(2) it adds that with 2...why does it add 1 with 2 and not 3 with 2?

[Junky]

Because you are calling the joe method on the bee object which contains 1 (1 + 2 = 3) not the zoo object which contains 3.

[Aimforthehead]

So obvious now. Thank you :)