API to track clipboard changes ?

[naved momin]

Is there any API which will notify me (Listener) whenever any changes occurs at system clipboard ?
I already know a method (by using Timer) to track clipboard changes but I think if i check for clipboard's data at 100ms then lots of CPU (which has just single core) time will be wasted

[Michael Dunn]

FlavorListener?

[naved momin]

Michael Dunn wrote:FlavorListener?

i tried this but i guess, this listener only listens to the data flavour for eg: if i copy image using ctrl-c then listener gets invoked but when i again copy another image this time listener doesn't invoke
please run the code and check out whats happening , All I wanted to track is clipboard changes no matter what data is in clipboard but when ever user performs any copy operation i should get notification , is there a way (I know using Timer but it will consume lot of CPU)

import java.awt.BorderLayout;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.FlavorEvent;
import java.awt.datatransfer.FlavorListener;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;


public class ClipboardDemo implements FlavorListener {

	/**
	 * @param args
	 */
	private JFrame frame;
	private JPanel panel;
	private JTextArea txtArea;
	private Clipboard clipboard;
	private static int i ;
	void start()
	{
		frame = new JFrame("demo");
		panel = new JPanel();
		txtArea =  new JTextArea(10,20);
		clipboard =  getSystemClipboard();
		panel.add( txtArea );
		
		frame.add( panel , BorderLayout.CENTER);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.pack();
		frame.setVisible(true);
	}
	private Clipboard getSystemClipboard() {
		clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
		clipboard.addFlavorListener(this);
		if(clipboard == null)
		{
			System.err.println("clipboard is null");
			return clipboard;
		}
		else
		{
			return clipboard;
		}
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new ClipboardDemo().start();
	}
	@Override
	public void flavorsChanged(FlavorEvent e) {
		
		txtArea.setText( txtArea.getText() + "\n" + "flavour has been changed "  + i);
		i++;
		
	}

}

[Michael Dunn]

> but when i again copy another image this time listener doesn't invoke

seems to work if the clipboard contents are cleared, but then there'd be nothing to paste

might be easier, provided there's not a lot of text components, to just override copy(),
and put a notification in there.

[naved momin]

Michael Dunn wrote:
seems to work if the clipboard contents are cleared, but then there'd be nothing to paste

lolzzz

Michael Dunn wrote:
might be easier, provided there's not a lot of text components, to just override copy(),
and put a notification in there.

I didn't get what you are saying please elaborate ....

[Michael Dunn]

all text components inherit
cut() copy() paste()
from JTextComponent

you can override those methods, to do a number of things

run this, copy "Hello World", now try to paste it into the 2nd textField,
and again into the 3rd textField

import javax.swing.*;
import java.awt.event.*;
import java.text.*;
class Testing
{
  public void buildGUI()
  {
    JTextField tf1 = new JTextField("Hello World");//normal textfield
    JTextField tf2 = new JTextField() {
      public void paste(){}//empty, cannot paste()
    };
    JTextField tf3 = new JTextField() {
      public void paste(){
        super.paste();
        JOptionPane.showMessageDialog(null,"paste operation");//or other notification
      }
    };
    JPanel p = new JPanel(new GridLayout(3,1));
    p.add(tf1);
    p.add(tf2);
    p.add(tf3);
    JFrame f = new JFrame();
    f.getContentPane().add(p);
    f.pack();
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}

same applies to cut() and copy()

[naved momin]

ohhh! I m soory i guess you are not getting my requirement I want to monitor each & every thing which sits in system clipboard
so for eg :
if you copy a .exe into clipboard i should get notified that something has copied into clipboard (No matter what it is...)

[Darryl Burke]

Well, Java's not really a good choice for writing spyware. You need a less well-behaved language for that.