Comment UnFocus un component swing jtextfield

Un journal serait mieux de le faire dans une boîte de dialogue modale, mais qui présente des problèmes en ce que la méthode requestFocusInWindow() doit être appelée après le composant est visible, mais qui est bloqué par le fait que le dialogue est modale!

Cet exemple utilise Rob Camick de RequestFocusListener (tel que présenté dans Dialogue Focus) pour gérer le focus après la boîte de dialogue est visible.

Remarque: C'est la façon dont elle apparaît avant que l'utilisateur ne fait rien. Le champ mot de passe est centré par défaut.

package test.t100.t001;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.event.AncestorEvent;
import javax.swing.event.AncestorListener;
public class LoginRequired {
LoginRequired() {
JFrame f = new JFrame("Login Required");
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setSize(400, 300);
f.setResizable(false);
f.setLocationByPlatform(true);
f.setVisible(true);
showLogin(f);
}
private void showLogin(JFrame frame) {
JPanel p = new JPanel(new BorderLayout(5,5));
JPanel labels = new JPanel(new GridLayout(0,1,2,2));
labels.add(new JLabel("User Name", SwingConstants.RIGHT));
labels.add(new JLabel("Password", SwingConstants.RIGHT));
p.add(labels, BorderLayout.WEST);
JPanel controls = new JPanel(new GridLayout(0,1,2,2));
JTextField username = new JTextField("Joe Blogs");
controls.add(username);
JPasswordField password = new JPasswordField();
password.addAncestorListener(new RequestFocusListener(false));
controls.add(password);
p.add(controls, BorderLayout.CENTER);
//LayoutManager l = new GroupLayout(p);
//p.setLayout(l);
JOptionPane.showMessageDialog(
frame, p, "Log In", JOptionPane.QUESTION_MESSAGE);
}
/**
* @param args  none
*/
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
@Override
public void run() {
new LoginRequired();
}
});
}
}
/**
*  Convenience class to request focus on a component.
*
*  When the component is added to a realized Window then component will
*  request focus immediately, since the ancestorAdded event is fired
*  immediately.
*
*  When the component is added to a non realized Window, then the focus
*  request will be made once the window is realized, since the
*  ancestorAdded event will not be fired until then.
*
*  Using the default constructor will cause the listener to be removed
*  from the component once the AncestorEvent is generated. A second constructor
*  allows you to specify a boolean value of false to prevent the
*  AncestorListener from being removed when the event is generated. This will
*  allow you to reuse the listener each time the event is generated.
*/
class RequestFocusListener implements AncestorListener
{
private boolean removeListener;
/*
*  Convenience constructor. The listener is only used once and then it is
*  removed from the component.
*/
public RequestFocusListener()
{
this(true);
}
/*
*  Constructor that controls whether this listen can be used once or
*  multiple times.
*
*  @param removeListener when true this listener is only invoked once
*                        otherwise it can be invoked multiple times.
*/
public RequestFocusListener(boolean removeListener)
{
this.removeListener = removeListener;
}
@Override
public void ancestorAdded(AncestorEvent e)
{
JComponent component = e.getComponent();
component.requestFocusInWindow();
if (removeListener)
component.removeAncestorListener( this );
}
@Override
public void ancestorMoved(AncestorEvent e) {}
@Override
public void ancestorRemoved(AncestorEvent e) {}
}

OriginalL'auteur Andrew Thompson

Je pense que donner le focus du clavier pour le champ nom d'utilisateur est le comportement correct, en supposant que c'est ce que l'utilisateur doit faire en premier. Au lieu de la compensation sur l'accent, pourquoi ne pas effacer seulement après que l'utilisateur tape quelque chose?:

import java.awt.*;
import javax.swing.*;
import javax.swing.text.Document;
public class PlaceholderTextField extends JTextField {
public static void main(final String[] args) {
final PlaceholderTextField tf = new PlaceholderTextField("");
tf.setColumns(20);
tf.setPlaceholder("All your base are belong to us!");
final Font f = tf.getFont();
tf.setFont(new Font(f.getName(), f.getStyle(), 30));
JOptionPane.showMessageDialog(null, tf);
}
private String placeholder;
public PlaceholderTextField() {
}
public PlaceholderTextField(
final Document pDoc,
final String pText,
final int pColumns)
{
super(pDoc, pText, pColumns);
}
public PlaceholderTextField(final int pColumns) {
super(pColumns);
}
public PlaceholderTextField(final String pText) {
super(pText);
}
public PlaceholderTextField(final String pText, final int pColumns) {
super(pText, pColumns);
}
public String getPlaceholder() {
return placeholder;
}
@Override
protected void paintComponent(final Graphics pG) {
super.paintComponent(pG);
if (placeholder.length() == 0 || getText().length() > 0) {
return;
}
final Graphics2D g = (Graphics2D) pG;
g.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(getDisabledTextColor());
g.drawString(placeholder, getInsets().left, pG.getFontMetrics()
.getMaxAscent() + getInsets().top);
}
public void setPlaceholder(final String s) {
placeholder = s;
}
}

Si vraiment vous voulez juste pour supprimer le focus, certaines options:

• component.setFocusable(false);
• KeyboardFocusManager.getCurrentKeyboardFocusManager().focusNextComponent();
• KeyboardFocusManager.getCurrentKeyboardFocusManager().clearGlobalFocusOwner();

OriginalL'auteur Peter Tseng