Re: How to detect focus l

From:

"Jeff Higgins" <jeff.higgins@THRWHITE.remove-dii-this>

Newsgroups:

comp.lang.java.gui

Date:

Wed, 27 Apr 2011 15:33:31 GMT

Message-ID:

<F_cVh.24$7W2.18@newsfe06.lga>

To: comp.lang.java.gui

Ian Wilson wrote:

clearlight@cantv.net wrote:

Hi,

I am new to Java. As a basic learning project, I started writing a no-
frill small general ledger application.

The basic design is a Frame containing a menu and a JTabbedPanel. When
a menu option is selected, a component derived from JPanel containing
the graphical interface for the data entry of the selected option is
created, added to the JTabbedPane component and the corresponding Tab
is selected.

Inside any of this panels, there are JTextFields that have to be
validated (via InputVerifiers).

Now, if focus is inside any of this JTextFields, and I select a new
option from the frame's menu, validation shouldn't be fired.

So far, I have tried to add a FocusListener to the JPanel descendents,
but it doesn't work as I expected: JPanel fires a focusLost event when
focus enters a JTextField contained within the panel itself, and fires
nothing when a menu option is selected.

If I establish a dependency between the main JFrame and the contained
JPanel derivates, I might perhaps design a sort of bidirectional
notification protocol, but I would like to avoid any dependence that
can be avoided.

So, is there a standard event that lets me know when the focus leaves
a JPanel (FocusListener doesn't work, because -at least in my
configuration: NetBeans 5.5, JDK 1.6, WinXP- it fires when a control
within the panel gains focus)?

I had a similar problem, an input panel with OK and Cancel buttons. If the
user is editing a JTextField then clicks Cancel, you don't want the
validation to kick in. I used this approach:

cancelButton.setVerifyInputWhenFocusTarget(false);

In your shoes I'd read the docs to see if
.setVerifyInputWhenFocusTarget(false) can be applied to your JMenuItems

Strange, that JMenu, JMenuBar don't seem to honor
..setVerifyInputWhenFocusTarget(false)

I could only get your suggestion to work using:
f.getRootPane().setVerifyInputWhenFocusTarget(false);
as below. I don't know what implications that may hold.
What about pop-up context menus?

Thanks,
Jeff Higgins

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

public class TestFocus {

  private static void createGUI() {
    JFrame f = new JFrame();
    JMenuBar menuBar = new JMenuBar();
    JMenu menu = new JMenu("Test");
    menu.setMnemonic(KeyEvent.VK_T);
    menuBar.add(menu);

    JTextField textFieldOne = new JTextField ();
    textFieldOne.setInputVerifier(new TestVerifier());
    JTextField textFieldTwo = new JTextField ("TextField2");
    JButton button = new JButton("Test");

    //menu.setVerifyInputWhenFocusTarget(false);
    f.getRootPane().setVerifyInputWhenFocusTarget(false);

    f.setJMenuBar(menuBar);
    f.getContentPane().add (textFieldOne, BorderLayout.NORTH);
    f.getContentPane().add (textFieldTwo, BorderLayout.CENTER);
    f.getContentPane().add (button, BorderLayout.SOUTH);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.pack();
    f.setVisible(true);
  }

  static class TestVerifier extends InputVerifier {
    public boolean verify(JComponent input) {
      JTextField tf = (JTextField) input;
      System.out.println("verify");
      return "pass".equals(tf.getText());
    }
  }

  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      public void run() {
        createGUI();
      }
    });
  }
}

---
* Synchronet * The Whitehouse BBS --- whitehouse.hulds.com --- check it out free usenet!
--- Synchronet 3.15a-Win32 NewsLink 1.92
Time Warp of the Future BBS - telnet://time.synchro.net:24