Could we write newlines in a JTextField?

Question

I'd like to write a kind of newline marker char or char-sequence in a JTextField so that the return value from the getText() could be displayed in multiple lines in a JTextArea.
I don't mean any effort of custom programming. I just like to find a Java and Swing inherent feature.
Am I struggling with an absolute impossible?

Answer 1

Here's a funny result. Could we get a cure?
import javax.swing.*;
import java.awt.event.*;
public class NLJTextFieldX extends JTextField{
  NLJTextFieldX njtf;
  public NLJTextFieldX(){
    super();
    init();
  public NLJTextFieldX(int columns){
    super(columns);
    init();
  void init(){
    getDocument().putProperty("filterNewlines", Boolean.FALSE);
    getInputMap().put(KeyStroke.getKeyStroke("ENTER"), "inputNewline");
    getActionMap().put("inputNewline", new NLAction());
    njtf = this;
  class NLAction extends AbstractAction{
    public void actionPerformed(ActionEvent e){
      // currently, can't handle arbitrary editing
      // on existing input string on the TF
      njtf.setText(njtf.getText() + "\n");
  public static void main(String[] args){
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    final NLJTextFieldX ntf = new NLJTextFieldX(30);
    frame.getContentPane().add(ntf, java.awt.BorderLayout.NORTH);
    JButton btn = new JButton("get text");
    frame.getContentPane().add(btn, java.awt.BorderLayout.SOUTH);
    frame.pack();
    frame.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e){
        String s = ntf.getText();
        System.out.println(s);
}