The JTextField Class

JTextField allows the user to enter a single line of text, scrolling the text if its size exceeds the physical size of the field. A JTextField fires an ActionEvent to any registered ActionListeners (including the Action set via the setAction( ) method, if any) when the user presses the Enter key.
 
JTextFields (and all JTextComponents) are automatically installed with a number of behaviors appropriate to the L&F, so cut/copy/paste, special cursor movement keys, and text-selection gestures should work without any extra intervention on your part.

import javax.swing.*;
import java.awt.event.*;

public class JTextFieldExample {

	public static void main(String[] args) {

		final JTextField tf = new JTextField("press <enter>", 20);
		tf.setHorizontalAlignment(JTextField.RIGHT);

		tf.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				int old = tf.getHorizontalAlignment();
				if (old == JTextField.LEFT)
					tf.setHorizontalAlignment(JTextField.RIGHT);
				if (old == JTextField.RIGHT)
					tf.setHorizontalAlignment(JTextField.CENTER);
				if (old == JTextField.CENTER)
					tf.setHorizontalAlignment(JTextField.LEFT);
			}
		});

		JFrame frame = new JFrame("JTextFieldExample");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(new java.awt.FlowLayout());
		frame.getContentPane().add(tf);
		frame.setSize(275, 75);
		frame.setVisible(true);
		tf.requestFocus();
	}
}