import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JTextField;
class MyTextField extends JTextField {
MyTextField(int len) {
super(len);
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
int key = evt.getKeyCode();
if (key == KeyEvent.VK_ENTER)
transferFocus();
}
});
}
}