Name: skT45625 Date: 09/06/2000


java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build
Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)

A user enters a value in to a text field and then trys to click an apply
button. The focus listener on the text field detects that the focus is being
lost so it post-validates the text field value. It finds that an illegal value
has been entered so it 1. requests that the focus be returned to it and 2.
displays a JOptionPane error message. Strange things happen with the state of
the JButton that was pressed.

Two examples:

1. IntField2 example - Type in a value other than "blah" into the text field
and then click a button. You will get the illegal value dialog and focus will
be returned to the text field. After you do this a couple of times (usually on
the second try), you will notice that when you move your mouse over the button
it appears pressed and when your mouse is not over the button, it is not
pressed. If you use this example with 1.2.2 instead of 1.3, the button stays
pressed all the time.

2. VerifierTest example - a modified version of a demo written by Sun to
demonstrate the InputVerifier class. Type in a value other than "pass" into
the top field then click on the button. You will notice the error dialog pops
up and then all appears fine. However, if you resize the frame, the button
will redraw and you will see that it is in the pressed state. After you mouse
over it for the first time, it will then show as pressed when the mouse is over
it.


// EXAMPLE 1 *******************************************

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


public class IntField2 {
    
    public static void main(String[] args) {
        JFrame f = new JFrame("IntField2 Demo");
        Container p = f.getContentPane();
        p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));

        final JTextField tf = new JTextField("blah");

        tf.addFocusListener(new FocusAdapter() {
            public void focusLost(FocusEvent e) {
                System.out.println("Trying to take focus");
                if (!tf.getText().equals("blah")) {
                    
                    SwingUtilities.invokeLater(new Runnable() {
                        public void run() {
                            tf.requestFocus();
                            
                            String message = "illegal value: " + tf.getText();
                            JOptionPane.showMessageDialog(tf.getParent(),
message,
                                                    "Illegal Value",
JOptionPane.ERROR_MESSAGE);
                                                    
                            
                        }
                    });
                    tf.setText("blah");
                    
                }

            }
        });

        final JButton b = new JButton("Button 1");
        b.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (b.hasFocus()) {
                    System.out.println("Button clicked." + b.isSelected() +
tf.getText());
                    //b.setBorder(RAISE);
                    System.out.print(b.getBackground());
                }
                    
                else
                    System.out.println("(didn't have focus)" + b.isSelected() +
tf.getText());
            }

        });

        final JButton c = new JButton("Button 2");
        c.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.out.println("trying to reset b");
                b.repaint();
                b.invalidate();
                b.revalidate();
                b.requestFocus();
                
            }
        });
        
        
// p.add(a);
        p.add(b);
        p.add(c);
        p.add(tf);
        
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        
        f.pack();
        f.setVisible(true);
    }
}


// EXAMPLE 2 ****************************************

 import java.awt.*;
 import java.util.*;
 import java.awt.event.*;
 import javax.swing.*;
 
 // This program demonstrates the use of the Swing InputVerifier class.
 // It creates two text fields; the first of the text fields expects the
 // string "pass" as input, and will allow focus to advance out of it
 // only after that string is typed in by the user.

 class VerifierTest extends JFrame {

  public VerifierTest () {
    JTextField tf;
    tf = new JTextField ("TextField1");

    getContentPane().add (tf, BorderLayout.NORTH);
    tf.setInputVerifier(new PassVerifier());

    tf = new JTextField ("TextField2");
    getContentPane().add (tf, BorderLayout.SOUTH);
    
    final JButton b = new JButton("Button");
    b.setVerifyInputWhenFocusTarget(true);
    getContentPane().add (b, BorderLayout.EAST);
    b.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            if (b.hasFocus())
                System.out.println("Button clicked");
        }
    });
                  
    addWindowListener (new MyWAdapter ());
  }



   public static void main (String [] args) {
     Frame f = new VerifierTest ();
     f.pack();
     f.show();
   }

   class MyWAdapter extends WindowAdapter {

     public void windowClosing(WindowEvent event) {
       System.exit (0);
     }
   }
               
   class PassVerifier extends InputVerifier {

     public boolean verify(JComponent input) {
       JTextField tf = (JTextField) input;
       String pass = tf.getText();
       if (pass.equals("pass")) return true;
       else {
             String message = "illegal value: " + tf.getText();
             JOptionPane.showMessageDialog(tf.getParent(), message,
                              "Illegal Value", JOptionPane.ERROR_MESSAGE);
       
         return false;
       }
     }
   }
 }
(Review ID: 109338)
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