Cut and Paste - Data Validation - JEditorPane

Question

I have an editor in development that uses JEditorPane which is supposed to accept only certain characters as its input.
Now if I use keystroke I am able to handle the input data entered using keyboard and it seems this is not a good idea :(.
But, for cut and paste this method does not work. So my questions are,
1) What is a good way to do data validation for Paste operations
2) I know that I might need to have a custom document but where do I do the validation in the custom document. I have checked using print statements and for my paste operation, it seems that the insert method in document does not get called.
3) Is using system clipboard and checking the text before insertion a better option.
4)What exactly happens when paste ie control C is pressed or paste from menu is clicked. I mean sequence of method calls.
I know I have asked many questions but answers to any of them will be highly appreciated !!
Thanks a lot for your help in advance :)

Answer 1

In my application, I subclass JTextField but you should be able to change it to JEditorPane. Here is a snippet of code that you need:
public class myTextField extends JTextField implements ClipboardOwner {
   public boolean processKeyBinding(KeyStroke ks, KeyEvent e, int condition, boolean pressed) {
      if (ks==KeyStroke.getKeyStroke(KeyEvent.VK_V,2)) {     // CTRL-V (paste text from clipboard)
         pasteText();
         return true;
      }   // there is more to my code but this will do
      return super.processKeyBinding(ks,e,condition,pressed);
   private void pasteText() {
      try {
         Transferable contents=clipboard.getContents(this);
         if (contents==null) return;
         int i=getCaretPosition();
         String line=(String)contents.getTransferData(DataFlavor.stringFlavor);
         String tmp=getText();
         int sStart=getSelectionStart();
         int sEnd=getSelectionEnd();
         if (sStart>=0) {
            setText(tmp.substring(0,sStart)+line+tmp.substring(sEnd));
            i=sStart;
         } else {
            if (i<tmp.length()) line+=tmp.substring(i);
            setText(tmp.substring(0,i)+line);
         sEnd=Math.min(i+line.length(),getText().length());
         setCaretPosition(sEnd);
         select(i,sEnd);
      } catch (Throwable t) {
         if (ExtDB!=null) ExtDB.setError("",t);
   public void lostOwnership(Clipboard cb, Transferable transferable) {
}The above has been formatted to look pretty, the following is more suitable for cut-n-paste:
public class myTextField extends JTextField implements ClipboardOwner {
   public boolean processKeyBinding(KeyStroke ks, KeyEvent e, int condition, boolean pressed) {
      if (ks==KeyStroke.getKeyStroke(KeyEvent.VK_V,2)) {     // CTRL-V (paste text from clipboard)
         pasteText();
         return true;
      }   // there is more to my code but this will do
      return super.processKeyBinding(ks,e,condition,pressed);
   private void pasteText() {
      try {
         Transferable contents=clipboard.getContents(this);
         if (contents==null) return;
         int i=getCaretPosition();
         String line=(String)contents.getTransferData(DataFlavor.stringFlavor);
         String tmp=getText();
         int sStart=getSelectionStart();
         int sEnd=getSelectionEnd();
         if (sStart>=0) {
            setText(tmp.substring(0,sStart)+line+tmp.substring(sEnd));
            i=sStart;
         } else {
            if (i<tmp.length()) line+=tmp.substring(i);
            setText(tmp.substring(0,i)+line);
         sEnd=Math.min(i+line.length(),getText().length());
         setCaretPosition(sEnd);
         select(i,sEnd);
      } catch (Throwable t) {
         if (ExtDB!=null) ExtDB.setError("",t);
   public void lostOwnership(Clipboard cb, Transferable transferable) {
}This will force the paste action to trigger a call to insertString.
;o)
V.V.
PS: my preference for the use of processKeyBinding has been labled inappropriate, the proper method according to the experts in this forum is to use a combination of InputMap/ActionMap.... so, you decide what you want to do.