Listening to All Focus Changes Between Components and windows : Focus Event « Event « Java

1. Java
2. Event
3. Focus Event

Listening to All Focus Changes Between Components and windows

 

import java.awt.Component;
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());
      }
    }
  }
}

   
  

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