Java by API/java.awt.datatransfer/ClipboardOwner

implements ClipboardOwner

import java.awt.Button;
import java.awt.Frame;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.TextArea;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.ClipboardOwner;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/** Taken from the Sun documentation on Clipboard API */
public class MainClass extends Frame implements ClipboardOwner, ActionListener {
  TextArea srcText, dstText;
  Button copyButton, pasteButton;
  Clipboard clipboard = getToolkit().getSystemClipboard();
  public MainClass() {
    super("Clipboard Test");
    GridBagLayout gridbag = new GridBagLayout();
    GridBagConstraints c = new GridBagConstraints();
    setLayout(gridbag);
    srcText = new TextArea(8, 32);
    c.gridwidth = 2;
    c.anchor = GridBagConstraints.CENTER;
    gridbag.setConstraints(srcText, c);
    add(srcText);
    copyButton = new Button("Copy Above");
    copyButton.setActionCommand("copy");
    copyButton.addActionListener(this);
    c.gridy = 1;
    c.gridwidth = 1;
    gridbag.setConstraints(copyButton, c);
    add(copyButton);
    pasteButton = new Button("Paste Below");
    pasteButton.setActionCommand("paste");
    pasteButton.addActionListener(this);
    pasteButton.setEnabled(false);
    c.gridx = 1;
    gridbag.setConstraints(pasteButton, c);
    add(pasteButton);
    dstText = new TextArea(8, 32);
    c.gridx = 0;
    c.gridy = 2;
    c.gridwidth = 2;
    gridbag.setConstraints(dstText, c);
    add(dstText);
    pack();
  }
  public void actionPerformed(ActionEvent evt) {
    String cmd = evt.getActionCommand();
    if (cmd.equals("copy")) {
      // Implement Copy operation
      String srcData = srcText.getText();
      if (srcData != null) {
        StringSelection contents = new StringSelection(srcData);
        clipboard.setContents(contents, this);
        pasteButton.setEnabled(true);
      }
    } else if (cmd.equals("paste")) {
      // Implement Paste operation
      Transferable content = clipboard.getContents(this);
      if (content != null) {
        try {
          String dstData = (String) content.getTransferData(DataFlavor.stringFlavor);
          dstText.append(dstData);
        } catch (Exception e) {
          System.out.println("Couldn"t get contents in format: "
              + DataFlavor.stringFlavor.getHumanPresentableName());
        }
      }
    }
  }
  public void lostOwnership(Clipboard clipboard, Transferable contents) {
    System.out.println("Clipboard contents replaced");
  }
  public static void main(String[] args) {
    MainClass test = new MainClass();
    test.setVisible(true);
  }
}