Can JButtons within applets copy to the clipboard?

Question

camickr wrote in another thread:
As always I would like to see the Applet used that caused the problem. We should not have to create our own applet to test this. As we all know from the original problem you may be missing/adding code. And this posting is way off topic so any new SSCCE along with a new question should be posted in a new posting. If I understand the problem is that Ctrl+C works on a text area, but it doesn't work for a JButton that tries to copy text from the same text area?Not quite. Ctrl+C works within a JTable, copying selected row(s) to the clipboard. The problem is getting a JButton to copy arbitrary text to the clipboard, having nothing to do with a JTable.
Well post the simple 20 line applet that demonstates this.Sorry, it's more than 20 lines. I included three approaches, Jeanette's, Walter's, and mine.
* Created on 06.12.2010
* Jeanette, Walter, and Rich
import java.awt.EventQueue;
import java.awt.datatransfer.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.Toolkit;
import javax.swing.*;
public class ThreeCopyButtons  extends JApplet  implements ClipboardOwner
    final JLabel first  = new JLabel("Larry");
    final JLabel second = new JLabel("Moe");
    final JLabel third  = new JLabel("Curly");
    static ThreeCopyButtons cb3;
    public JPanel getContent() {
        JButton kleo = new JButton("Kleo");
     cb3 = this;
        TransferHandler handler = new TransferHandler() {
             * @inherited <p>
            @Override
            protected Transferable createTransferable(JComponent c) {
                return new StringSelection(cb3.toString());
             * @inherited <p>
            @Override
            public int getSourceActions(JComponent c) {
                return COPY;
        kleo.setTransferHandler(handler);
        kleo.setAction(TransferHandler.getCopyAction());
        kleo.setText("Kleo");  // gets overridden by "copy"
     AppletCopyButton walt = new AppletCopyButton("Walt", toString());
     JButton rich = new JButton("Rich");
     rich.addActionListener( new ActionListener() {
         public void actionPerformed(ActionEvent e) {
          StringSelection ss = new StringSelection(cb3.toString());
          Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard();
          cb.setContents(ss, cb3);
        JComponent buttons = new JPanel();
        buttons.add(kleo);
        buttons.add(walt);
        buttons.add(rich);
        JPanel labels = new JPanel();
        labels.add(first);
        labels.add(second);
        labels.add(third);
        JPanel box = new JPanel();
        box.setLayout(new BoxLayout(box, BoxLayout.Y_AXIS));
     box.add(buttons);
     box.add(labels);
        return box;
    public String toString() {
     String s = first.getText() + "\t" +
             second.getText() + "\t" +
             third.getText();
     return(s);
    // Empty method needed for implementation of the ClipboardOwner interface.
    public void lostOwnership( Clipboard aClipboard, Transferable aContents) {
      //do nothing
    // method expected by applets
    public void init()
    { // the static block above should have already executed
     try {
         javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
          public void run() {
              JPanel frame = getContent();
              setContentPane(frame);
     } catch (Exception e) {
         System.err.println("makeContent() failed to complete: " + e);
         e.printStackTrace();
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                frame.add(new ThreeCopyButtons().getContent());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
// Walter Laan
class AppletCopyButton extends JButton {
    public AppletCopyButton(String label, String text) {
        super(label);
     final String clip = text;
        setTransferHandler(new TransferHandler() {
            // @Override
            protected Transferable createTransferable(JComponent c) {
                return new StringSelection(clip);
            // @Override
            public int getSourceActions(JComponent c) {
                return COPY;
        addActionListener(new ActionListener() {
            // @Override
            public void actionPerformed(ActionEvent e) {
                Action copy = TransferHandler.getCopyAction();
                copy.actionPerformed(new ActionEvent(AppletCopyButton.this,
                        ActionEvent.ACTION_PERFORMED, "copy"));
}Here is a manifest file I call "3cbManifest.txt".
Main-Class: ThreeCopyButtonsMake sure you preserve the trailing carriage return.
]javac ThreeCopyButtons.java
]jar cvfm ThreeCopyButtons.jar 3cbManifest.txt *.class
]java -jar ThreeCopyButtons.jar
(The latter command simply tests, but it is running as program, not applet.)
And here is a short HTML file to run it as an applet. I call it "3cb.html".
<html>
<head><title>TestApplet</title></head>
<body>
<applet code="ThreeCopyButtons.class"
        archive="ThreeCopyButtons.jar"
        width="450" height="300">
Your browser is completely ignoring the <i>applet</i> tag!
</applet>
</body>
</html>The three buttons match our three approaches:
* Kleo -- Jeanette's approach
* Walt -- Walt's approach
* Rich -- my approach
All three methods work fine as a program, whether running directly as classes or from the .jar. None however work as an applet, from the HTML page.
To test either as applet or program:
1) open a text editor
2) type something short
3) Ctrl+C copy what you typed
4) click the Kleo button
5) in editor, click <enter> and Ctrl+V to paste
6) observe whether you see the text from step 3 or "Larry Moe Curly", with <tabs> between words.
7) repeat steps 3-6 for the Walt and Rich buttons
If you can figure out how to get the applet to bypass its security wall, great. We've found a bug in Java's applet security. If not, I am resigned to having the button in my actual app copy info to the table instead of to the clipboard.

Answer 1

RichF wrote:
You are right, but aw gee whiz. Have you ever written something that you think is pretty neat, then have to throw it away? hahahahahaha ... sure, happens nearly every day :-)
My class QEPanel, which handles each row of the statistics, is like that.yeah, have seen it: pretty nasty mixing of view and data <g>
Hmm, I wouldn't actually have to throw most of it away. :) correct ...
The JLabel <b>label</b>s would become the table column labels, and the other JLabels would become integers specifying column. except that I don't completely understand what you are after here (ehem: get your vocabulary right, sir) a clean separation would map the data-part of a QEPanel into a QEBean, with properties title (was: label), percentRed ... etc. Something like:
public class QEBean extends AbstractBean {
    private float sumRed, sumGrn, sumBlu;
    private float minDist = 9999999;
    private float maxDist = 0;
    private double sumDist;
    private int count;
    private int entries;
    private CountPerEntries countPerEntries;
    private String title;
    public QEBean(String title) {
        this.title = title;
    public void reset() {
        // do reset
        firePropertyChange(null, null, null);
    public void updateData(Color quantized, Color actual) {
        // do update internals
        firePropertyChange(null, null, null);
//------------ getters...
    public String getTitle() {
        return title;
    public float getPercentRed() {
        if (count == 0)
            return 0f;
        return sumRed / count;
    // more getters
}Then implement a specialized TableModel which knows about QEBean
public class QEBeanTableModel extends AbstractTableModel {
    List<QEBean> errors = new ArrayList<QEBean>();
    private PropertyChangeListener errorChangeListener;
    @Override
    public int getColumnCount() {
        return 7;
    @Override
    public int getRowCount() {
        return errors.size();
    @Override
    public Class<?> getColumnClass(int columnIndex) {
        switch (columnIndex) {
               // implement as appropriate
        return Object.class;
    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        QEBean error = errors.get(rowIndex);
        switch (columnIndex) {
        case 0:
            return error.getTitle();
        case 1:
            return error.getPercentRed();
          // more as appropriate
        return null;
    public void addError(QEBean error) {
        int oldSize = getRowCount();
        error.addPropertyChangeListener(getPropertyChangeListener());
        errors.add(error);
        fireTableRowsInserted(oldSize, oldSize);
    public QEBean getError(int row) {
        return errors.get(row);
    private PropertyChangeListener getPropertyChangeListener() {
        if (errorChangeListener == null) {
            errorChangeListener = new PropertyChangeListener() {
                @Override
                public void propertyChange(PropertyChangeEvent evt) {
                    int row = errors.indexOf(evt.getSource());
                    fireTableRowsUpdated(row, row);
        return errorChangeListener;
    public void resetAll() {
        for (QEBean error : errors) {
            error.reset();
}Then use the model in HelpBox:
// init model and keep in field
     qErrors = new QEBeanTableModel();
     qErrors.addError(new QEBean("Hex QE"));
     qErrors.addError(new QEBean("Name QE"));
     qErrors.addError(new QEBean("Mismatch QE"));
     qErrors.addError(new QEBean("SearchAccuracy"));
        // can't resist - JXTable would make customization so much easier :-)
     // JXTable errorTable = new JXTable(qErrors);
     JTable errorTable = new JTable(qErrors);
     errorTable.setBackground(Color.BLACK);
     errorTable.setSelectionBackground(Color.BLACK);
     errorTable.setForeground(Color.WHITE);
     errorTable.setSelectionForeground(Color.WHITE);
     errorTable.setGridColor(Color.BLACK);
        // install renderers which produce an output similar to the labels
       panel.add(errorTable)
// in the update methods - update the QEBeans stored in the model
    public void updateQE(int which, String q, String a)
     Color     quantized = Color.black;
     Color     actual = Color.black;
     int     rgb[] = { 0, 0, 0 };
     NTC.getRGB(q, rgb);
     quantized = new Color(rgb[0], rgb[1], rgb[2]);
     NTC.getRGB(a, rgb);
     actual = new Color(rgb[0], rgb[1], rgb[2]);
     qErrors.getError(which -1).updateData(quantized, actual);
// similar in reset, updateEntriesThat's all and will give you an output very similar to the rows of individual labels, only more symetric.
The toString() method would go away because row toString() is already built into JTable.ehhh? No, not that I know of :-) The default renderer uses the toString of the cell value, the row is not involved.
>
Then you can implement the button's action to copy that error table's content to the clipboard. Better usability ensured, IMO.I'll just throw away the darn button. The colorTable doesn't have one, so why should the statisticsTable? sure, that's an option - the visual setup outlined above is for hiding the table-nature, if you want it expose, just do - no problem.
Cheers
Jeanette