Listen to the paste events JTextArea

Question

I want to call a function when the user pastes text in my JTextArea. Is there any event generated when the text is pasted to the JTextArea and which listener can I use to trigger my function on this event?

Answer 1

One possible solution (and I hope some one has a better one) would be to replace the key binding Action responsible for actually performing the paste operation.

Now, before you do this, the default paste operation is not trivial, instead, I would replace the default paste Action with a proxy, which could call the original, but would allow you to intercept the operation, but not have to re-implement the functionality yourself, for example...

public class ProxyAction extends AbstractAction {

    private Action action;

    public ProxyAction(Action action) {
        this.action = action;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        action.actionPerformed(e);
        System.out.println("Paste Occured...");
    }

}

Then you would simply need to look up the default Action and replace it...

JTextArea ta = new JTextArea(10, 10);
Action action = ta.getActionMap().get("paste-from-clipboard");
ta.getActionMap().put("paste-from-clipboard", new ProxyAction(action));

The problem here is, this won't tell you if the operation failed or succeeded or what was actually pasted. For that, you could use a DocumentListener, registered before you call the default Action which could record the changes to the document. Obviously, you'd want to deregister this after the default action ;)...

Now, equally, you could just override the paste method of the JTextArea, which equates to about the same thing, but, the first option would be more portable...

As an idea...

Take a look at How to Use Actions and How to Use Key Bindings for more details