Java - How to setEnabled() on paste Action?

Question

I am doing my own Notepad in Java. Basic part is almost done. But i have big problem with JMenuItem which pastes words to JTextPane. It works(pasting), but i want that JMenuItem reacts:

when is something in memory(copy - from anywhere) => JMenuItem will be setEnabled(true)

when isnt something in memory > JMenuItem will be setEnabled(false)

private static JMenuItem editPaste; // atribut
editPaste = new JMenuItem(new DefaultEditorKit.PasteAction()); //in private method

I have no idea, what I should listened(listener of what??) for this action. I did not see that anywhere(http://docs.oracle.com/javase/tutorial/uiswing/components/generaltext.html).

Do you want to have separate (your custom) memory from the OS defaults? Then - yes, you can implement it and fire events on memory status changes — Tala, Aug 09 '13 at 12:44
@Tala No, I dont want to separate it(I dont know exactly). I want the same funkcionality like in Notepad or Notepad++. — MmM ..., Aug 09 '13 at 13:17
hmm ... isn't there nearly always something on the clipboard? Anyway, the default textActions have no enablement management at all: you have to implement it yourself. For paste you can try a FlavourListener on the clipboard that enables/disables the action as appropriate. — kleopatra, Aug 09 '13 at 13:43
some details as to (the missing) enablement management in text actions: https://java.net/jira/browse/SWINGX-289 — kleopatra, Aug 09 '13 at 14:14
There's a class ClipBoard in java and you can register a FlavourListener on it. May that helps. I've never tried. — Bernd Ebertz, Aug 09 '13 at 15:08

score 0 · Accepted Answer · edited May 23 '17 at 11:56

Thanks you for advices and keywords. I win, partly :)

For my case works:

// atributes
private static JMenuItem editPaste;
private static Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard(); 
// private method
clipboard.addFlavorListener(new ListenerPaste());
editPaste = new JMenuItem(new DefaultEditorKit.PasteAction());
editPaste.setEnabled(false);
// listener 
private static class ListenerPaste implements FlavorListener {
    public void flavorsChanged(FlavorEvent e) {
        checkPaste();
    }
}
// private method
private static void checkPaste() {
    try {
        if(clipboard.getData(DataFlavor.stringFlavor) != null) {
            editPaste.setEnabled(true);
            // JOptionPane.showMessageDialog(null, (String) clipboard.getData(DataFlavor.stringFlavor));
        }
    } catch (UnsupportedFlavorException e1) {
        e1.printStackTrace();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
}
// in constructor we check it also
checkPaste();

I do not know, if this is the most appropriate solution, but for me it works. That line which is commented - for real time it doesnt work very well - more: listen to clipboard changes, check ownership? Next source: http://www.avajava.com/tutorials/lessons/how-do-i-get-a-string-from-the-clipboard.html

Java - How to setEnabled() on paste Action?

1 Answers1