How to write a undo and redo implementation?

[Daniel Graham]

Hello. I'm on the point of getting some experiences in Java Desktop applications.

But I've got one challenge right now.

I wish  to know how I could add a backward/forward functionality to the app I'm currently building.

So please, is there any java class or any external java source code that I could use to add to my application?


Please any help shall be mostly appreciated.

[Carey Brown]

I don't know what you mean by backwards/forwards. Can you give an example?

Are you talking about an "undo" / "re-do" capability?

[Daniel Graham]

Yeah. That's the name: I meant the undo and redo functionalities..

[Campbell Ritchie]

. . . and welcome to the Ranch

[Daniel Graham]

Thanks Campbell...

[Carey Brown]

You need to be able to capture the "state" of your program, that is any item that might be changed by the user, such as text, lists, colors, selections, database, files, etc..

Some programs allow you to undo and redo several levels deep. To keep things simple only allow one undo and possible redo for now. When you initialize the interface capture it's state in an object. After every change move the state object to a redo object. If the use selects redo, then restore the state from the redo object.

[Daniel Graham]

Okay, so that's the strategy. I appreciate that.

So how do we go about that?

I just came to know about the "UndoManager" class. Do you think this class can help me undo all textfields, lists, colors, selections, database, files, etc in my app?

[Paul Clapham]

Yes, absolutely. It works great once you work out how to use it. If you search for java undo tutorial you'll get a whole lot of people who want you to read their tutorial about how to do that, too.

[Daniel Graham]

Alright. Copy that.

Thanks