Java by API/java.awt/KeyboardFocusManager

KeyboardFocusManager: addPropertyChangeListener(PropertyChangeListener listener)

 
import java.awt.ruponent;
import java.awt.KeyboardFocusManager;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
public class Main {
  public static void main(String[] argv) {
    KeyboardFocusManager.getCurrentKeyboardFocusManager().addPropertyChangeListener(
        new FocusChangeListener());
  }
}
class FocusChangeListener implements PropertyChangeListener {
  public void propertyChange(PropertyChangeEvent evt) {
    Component oldComp = (Component) evt.getOldValue();
    Component newComp = (Component) evt.getNewValue();
    if ("focusOwner".equals(evt.getPropertyName())) {
      if (oldComp == null) {
        System.out.println(newComp.getName());
      } else {
        System.out.println(oldComp.getName());
      }
    } else if ("focusedWindow".equals(evt.getPropertyName())) {
      if (oldComp == null) {
        System.out.println(newComp.getName());
      } else {
        System.out.println(oldComp.getName());
      }
    }
  }
}

KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS

 
import java.awt.AWTKeyStroke;
import java.awt.KeyboardFocusManager;
import java.util.HashSet;
import java.util.Set;
import javax.swing.KeyStroke;
public class Main {
  public static void main(String[] argv) throws Exception {
    Set<AWTKeyStroke> set = new HashSet<AWTKeyStroke>(KeyboardFocusManager
        .getCurrentKeyboardFocusManager().getDefaultFocusTraversalKeys(
            KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS));
    set.add(KeyStroke.getKeyStroke("F3"));
    KeyboardFocusManager.getCurrentKeyboardFocusManager().setDefaultFocusTraversalKeys(
        KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, set);
  }
}

KeyboardFocusManager: clearGlobalFocusOwner()

 

import java.awt.KeyboardFocusManager;
public class Main {
  public static void main(String[] argv) throws Exception {
    KeyboardFocusManager.getCurrentKeyboardFocusManager().clearGlobalFocusOwner();
  }
}

KeyboardFocusManager: focusNextComponent()

 
import java.awt.ruponent;
import java.awt.GridLayout;
import java.awt.KeyboardFocusManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class MainClass {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Focus Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    ActionListener actionListener = new ActionFocusMover();
    MouseListener mouseListener = new MouseEnterFocusMover();
    frame.setLayout(new GridLayout(3, 3));
    for (int i = 1; i < 10; i++) {
      JButton button = new JButton(Integer.toString(i));
      button.addActionListener(actionListener);
      button.addMouseListener(mouseListener);
      if ((i % 2) != 0) {
        button.setFocusable(false);
      }
      frame.add(button);
    }
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}
class ActionFocusMover implements ActionListener {
  public void actionPerformed(ActionEvent actionEvent) {
    KeyboardFocusManager manager = KeyboardFocusManager
        .getCurrentKeyboardFocusManager();
    manager.focusNextComponent();
  }
}
class MouseEnterFocusMover extends MouseAdapter {
  public void mouseEntered(MouseEvent mouseEvent) {
    Component component = mouseEvent.getComponent();
    if (!component.hasFocus()) {
      component.requestFocusInWindow();
    }
  }
}

KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS

 

import java.awt.AWTKeyStroke;
import java.awt.KeyboardFocusManager;
import java.util.HashSet;
import java.util.Set;
import javax.swing.JButton;
import javax.swing.KeyStroke;
public class Main {
  public static void main(String[] argv) throws Exception {
    JButton component = new JButton("a");
    Set<AWTKeyStroke> set = new HashSet<AWTKeyStroke>(component
        .getFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS));
    set.add(KeyStroke.getKeyStroke("F2"));
    component.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, set);
  }
}

KeyboardFocusManager: getFocusedWindow()

 

import java.awt.KeyboardFocusManager;
import java.awt.Window;
public class Main {
  public static void main() {

    Window windowFocusOwner =
    KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusedWindow();
  }
}

KeyboardFocusManager: getFocusOwner()

 

import java.awt.ruponent;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.FocusTraversalPolicy;
import java.awt.KeyboardFocusManager;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) {
    JFrame frame = new JFrame();
    JButton component1 = new JButton("1");
    JButton component2 = new JButton("2");
    JButton component3 = new JButton("3");
    frame.setLayout(new FlowLayout());
    frame.add(component1);
    frame.add(component2);
    frame.add(component3);
    frame.pack();
    frame.setVisible(true);
    System.out.println(findPrevFocus().getName());
  }
  public static Component findPrevFocus() {
    Component c = KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
    Container root = c.getFocusCycleRootAncestor();
    FocusTraversalPolicy policy = root.getFocusTraversalPolicy();
    Component prevFocus = policy.getComponentBefore(root, c);
    if (prevFocus == null) {
      prevFocus = policy.getDefaultComponent(root);
    }
    return prevFocus;
  }
}

KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS

 
import java.awt.AWTKeyStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
import javax.swing.JButton;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
public class MainClass extends JFrame {
  public MainClass() {
    super("Focus Example");
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    MyPanel mypanel = new MyPanel();
    JButton button1 = new JButton("One");
    JButton button2 = new JButton("Two");
    JButton button3 = new JButton("Three");
    JButton button4 = new JButton("Four");
    JButton button5 = new MyButton("Five*");
    JButton button6 = new MyButton("Six*");
    JButton button7 = new JButton("Seven");
    mypanel.add(button2);
    mypanel.add(button3);
    JInternalFrame frame1 = new JInternalFrame("Internal Frame 1", true, true, true, true);
    frame1.setBackground(Color.lightGray);
    frame1.getContentPane().setLayout(new GridLayout(2, 3));
    frame1.setSize(300, 200);
    frame1.getContentPane().add(button1);
    frame1.getContentPane().add(mypanel);
    frame1.getContentPane().add(button4);
    frame1.getContentPane().add(button5);
    frame1.getContentPane().add(button6);
    frame1.getContentPane().add(button7);
    JDesktopPane desktop = new JDesktopPane();
    desktop.add(frame1, new Integer(1));
    desktop.setOpaque(true);
    // Now set up the user interface window.
    Container contentPane = getContentPane();
    contentPane.add(desktop, BorderLayout.CENTER);
    setSize(new Dimension(400, 300));
    frame1.setVisible(true);
    setVisible(true);
  }
  public static void main(String[] args) {
    new MainClass();
  }
}
class MyButton extends JButton {
  public MyButton(String s) {
    super(s);
  }
  public boolean isFocusable() {
    return false;
  }
}
class MyPanel extends JPanel {
  public MyPanel() {
    super(true);
    java.util.Set upKeys = new java.util.HashSet(1);
    upKeys.add(AWTKeyStroke.getAWTKeyStroke(KeyEvent.VK_UP, 0));
    setFocusTraversalKeys(KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, upKeys);
  }
  public boolean isFocusCycleRoot() {
    return true;
  }
}