import java.awt.event.FocusAdapter; import java.awt.event.FocusEvent; import javax.swing.JButton; import javax.swing.JFrame; public class Main { public static void main(String[] argv) throws Exception { JButton component = new JButton("a"); component.addFocusListener(new MyFocusListener()); JFrame f = new JFrame(); f.add(component); f.pack(); f.setVisible(true); } } class MyFocusListener extends FocusAdapter { public void focusGained(FocusEvent evt) { System.out.println("gained the focus."); } public void focusLost(FocusEvent evt) { System.out.println("lost the focus."); boolean isTemporary = evt.isTemporary(); } }