import java.awt.BorderLayout;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JSplitPane;
public class Main {
public static void main(String[] a) {
JFrame horizontalFrame = new JFrame();
horizontalFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent topButton = new JButton("Left");
JComponent bottomButton = new JButton("Right");
final JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
HierarchyListener hierarchyListener = new HierarchyListener() {
public void hierarchyChanged(HierarchyEvent e) {
long flags = e.getChangeFlags();
System.out.println(e.getSource());
if ((flags & HierarchyEvent.SHOWING_CHANGED) ==
HierarchyEvent.SHOWING_CHANGED) {
splitPane.setDividerLocation(.75);
}
}
};
splitPane.addHierarchyListener(hierarchyListener);
splitPane.setTopComponent(topButton);
splitPane.setBottomComponent(bottomButton);
horizontalFrame.add(splitPane, BorderLayout.CENTER);
horizontalFrame.setSize(150, 150);
horizontalFrame.setVisible(true);
}
}