JTextArea new line on shift + enter

Question

I\'ve added a keylistener to my JTextArea field, but it doesn\'t behave as I expected.

inputTextArea.addKeyListener(new KeyAdapter() {
public void keyPressed(Key         


        

Answer 1

You may use the InputMap and ActionMap of the JTextArea to map the key strokes to actions:

private static final String TEXT_SUBMIT = "text-submit";
private static final String INSERT_BREAK = "insert-break";
...
private void initialize() {
    InputMap input = inputTextArea.getInputMap();
    KeyStroke enter = KeyStroke.getKeyStroke("ENTER");
    KeyStroke shiftEnter = KeyStroke.getKeyStroke("shift ENTER");
    input.put(shiftEnter, INSERT_BREAK);  // input.get(enter)) = "insert-break"
    input.put(enter, TEXT_SUBMIT);

    ActionMap actions = inputTextArea.getActionMap();
    actions.put(TEXT_SUBMIT, new AbstractAction() {
        @Override
        public void actionPerformed(ActionEvent e) {
            submitText();
        }
    });
}
...
private void submitText() {
    // TODO
}  

The original action for ENTER - "insert-break" - is used for shift ENTER.

Answer 2

Try using keyTyped and not keyPressed. I beleive keyPressed gives you an event for the shift and for the enter, whereas keyTyped gives you one combined event with a modifier.

Answer 3

Instead of doing the actions immediately on receiving the event, sequence them for later by posting them using SwingUtilities.invokeLater(). The code should look like:

if(k.isShiftDown()) {
   SwingUtilities.invokeLater(new Runnable() {
      public void run() {
         inputTextArea.append(" \n");
      }
   });
} else {
   SwingUtilities.invokeLater(new Runnable() {
      public void run() {
          //rest of the else body here
      }
   });

}

In my opinion, the problems seen here are because application-defined actions and internal actions are not being properly sequenced, leading to repaints happening before the text has been modified.