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  Making a copy versus changing a pointer location.  (Read 838 times)
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Offline Manfred

Senior Newbie




Java games rock!


« Posted 2004-10-26 22:26:34 »

I'd like to copy and Object, not set a pointer.  Like so:

MyObject o1 = new MyObject();
MyObject o2 = o1;

Seems as though o2 is just pointing to o1.  I want o2 to be a copy of o1.  How might I do that?
Offline oNyx

JGO Coder


Medals: 2


pixels! :x


« Reply #1 - Posted 2004-10-27 00:01:20 »

You always only have references to objects. So in your example...

MyObject o1 = new MyObject();
MyObject o2 = o1;

...neither o1 or o2 are the object. It's just a reference. So if you do something like...

MyObject o1 = new MyObject("one");
MyObject o2 = o1;
MyObject o1 = new MyObject("two");

o2 will hold a reference to "one" whereas o1 will hold a reference to "two" (the new object). [And if there isn't a reference to an object it will get garbage collected]

If you want to create a copy you need to use clone(); like...

MyObject o1 = new MyObject("one");
MyObject o2 = o1.clone();

then you'll have two different but (content wise) identical objects.

Btw you'll need to implement the Cloneable interface.
http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Cloneable.html

弾幕 ☆ @mahonnaiseblog
Offline Manfred

Senior Newbie




Java games rock!


« Reply #2 - Posted 2004-10-27 12:44:26 »

Thank you again, sir.
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