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.
The following program presents a JTextField for the user to edit (shown in
Figure 19-3). The JTextField is initially right-justified, but
the justification changes each time the Enter key is pressed.
// JTextFieldExample.java // 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( ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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