Is there a way to catch un-displayable characters before they are written to a JTextArea?

I alter my keyTyped behaviour to default output the char to the JTextArea, however when I copy and paste, it produces an un-displayable character.

I need this to work across multiple operating systems so using case 22: doesn't work as this doesn't apply on Mac's. Does sun either have a case for catching paste's/copy's free from OS constraints, or does someone know a good work-开发者_如何学编程around?

You might want to investigate document filters.

Adding a document filter will allow you to modify (or even prevent) a string that is added to the JTextArea's document. A custom document filter can be added if your text area is using some subclass of AbstractDocument as the document implementation. Something like this:

AbstractDocument doc = (AbstractDocument)textArea.getDocument(); 
doc.setDocumentFilter( new DocumentFilter() {
  public void insertString( FilterBypass fb, int offset, String string,
      AttributeSet attr ) throws BadLocationException
  {
    // Test string here and modify if required, then call super.insertString()
    // (usually called on a "paste")
  }

  public void replace( FilterBypass fb, int offset, int length,
      String text, AttributeSet attrs ) throws BadLocationException
  {
    // Test string here and modify if required, then call super.replace()
    // (usually called when characters are typed)
  }
});

(In your "real" implementation, you may want to test nicely that an AbstractDocument is actually in use rather than the cast I've done).

I think you might be able to modify the clipboard behavior by:

1. Create a TransferHandler that implements the importData() function
2. Set the transferHandler on your function by calling JComponent.setTransferHandler()