Java tutorial
import java.util.Date; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTabbedPane; import javax.swing.event.AncestorEvent; import javax.swing.event.AncestorListener; public class Main { private static JPanel createPanel() { JPanel panel = new JPanel(); final JLabel label = new JLabel(new Date().toString()); panel.add(label); panel.addAncestorListener(new AncestorListener() { @Override public void ancestorAdded(AncestorEvent event) { // start animation label.setText(new Date().toString()); } @Override public void ancestorRemoved(AncestorEvent event) { // stop animation } @Override public void ancestorMoved(AncestorEvent event) { } }); return panel; } public static void main(String[] args) { JFrame f = new JFrame(); final JTabbedPane jtp = new JTabbedPane(); jtp.add("One", createPanel()); jtp.add("Two", createPanel()); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(jtp); f.pack(); f.setVisible(true); } }