import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ScrollDemo extends JFrame implements ActionListener {
    JScrollPane scrollPane;
    
    public ScrollDemo() {
	super("JScrollPane Demonstration");
	
	scrollPane = new JScrollPane(getScrollComponent());
	
	//Just for demonstration, set the vertical scrollbar to always show.
	scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
	
	//Set a row and column header with a large font.
	JLabel l = new JLabel("Column Header");
	l.setFont(new Font("Serif", Font.BOLD, 40));
	scrollPane.setColumnHeaderView(l);
	l = new JLabel("RH");
	l.setFont(new Font("Serif", Font.BOLD, 40));
	scrollPane.setRowHeaderView(l);
	
	//Place buttons in the corners.
	JButton b = new JButton("UL");
	b.addActionListener(this);
	scrollPane.setCorner(ScrollPaneConstants.UPPER_LEFT_CORNER, b);
	b = new JButton("UR");
	b.addActionListener(this);
	scrollPane.setCorner(ScrollPaneConstants.UPPER_RIGHT_CORNER, b);
	b = new JButton("LL");
	b.addActionListener(this);
	scrollPane.setCorner(ScrollPaneConstants.LOWER_LEFT_CORNER, b);
	b = new JButton("LR");
	b.addActionListener(this);
	scrollPane.setCorner(ScrollPaneConstants.LOWER_RIGHT_CORNER, b);
	
	getContentPane().add(scrollPane, BorderLayout.CENTER);
	addWindowListener(new WindowAdapter() {
		public void windowClosing(WindowEvent e) {
		    System.exit(0);
		}
	    });
	setSize(300, 200);
	setVisible(true);
    }
    
    public void actionPerformed(ActionEvent e) {
	System.out.println("action command = " + e.getActionCommand());
    }
    
    public JPanel getScrollComponent() {
	//Assemble the scrollable component, in this case a JPanel.
	JPanel p = new JPanel();
	p.setBackground(Color.BLUE);
	p.setPreferredSize(new Dimension(500, 500));
	return p;
    }
    
    public static void main(String args[]) {
	new ScrollDemo();
    }
}