copying an object

[Niels Tielenburg]

I want to copy an object called t1. I do that like this:

		Tester t1 = new Tester();
		t1.setTest("niels");
		System.out.println(t1);
		Tester t2 = t1;
		System.out.println(t1);
		System.out.println(t2);
		t1.setTest("iemand");
		System.out.println(t1);
		System.out.println(t2);

What I don't understand is the output:

name: niels
name: niels
name: niels
name: iemand
name: iemand

Why, when I set the test value of t1 to another value, the value of t2 also changes to that value?

[Campbell Ritchie]

You have not copied the object. You have two references to the same object, set up with Tester t2 = t1; For copying, you should override the clone() method and implement the Cloneable interface, or maybe better, give your Tester class a copy constructor.

[Niels Tielenburg]

ok thanks, got it working ;)

[Jesper de Jong]

Maybe this confuses you because you know C++?

This happens because variables in Java do not represent the objects themselves directly (like in C++); in Java, variables are references to objects. Line 4 in your code makes variable t2 refer to the same object that variable t1 refers to. It doesn't copy the object itself.

[Campbell Ritchie]

Niels Tielenburg wrote:ok thanks, got it working ;)

Well done, and "you're welcome"

[Niels Tielenburg]

oh yes, thank you for your help:P