package swingExamples;

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

// JPanel demo from "Absolute Java"
// with some modifications
public class PanelDemo extends JFrame implements ActionListener
{
    private JPanel greenPanel;
    private JPanel whitePanel;
    private JPanel grayPanel;
    private JButton greenButton, whiteButton, grayButton;
    
    public static void main(String[] args)
    {
        PanelDemo gui = new PanelDemo( );
        gui.setVisible(true);
    }

    public PanelDemo( )
    {
        super("Panel Demonstration");
        setSize(300, 300);
        setLocation(200, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout( ));

        // mainPanel contains the panels that show the colors
        JPanel mainPanel = new JPanel( );
        mainPanel.setLayout(new GridLayout(1, 3));

        greenPanel = new JPanel( );
        greenPanel.setBackground(Color.LIGHT_GRAY);
        mainPanel.add(greenPanel);

        whitePanel = new JPanel( );
        whitePanel.setBackground(Color.LIGHT_GRAY);
        mainPanel.add(whitePanel);

        grayPanel = new JPanel( );
        grayPanel.setBackground(Color.LIGHT_GRAY);
        mainPanel.add(grayPanel);

        add(mainPanel, BorderLayout.CENTER);

        // buttonPanel holds the buttons at the bottom of the screen
        JPanel buttonPanel = new JPanel( );
        buttonPanel.setBackground(Color.LIGHT_GRAY);
        buttonPanel.setLayout(new FlowLayout( ));

        greenButton = new JButton("Green");
        greenButton.setBackground(Color.GREEN);
        greenButton.addActionListener(this);
        buttonPanel.add(greenButton);

        whiteButton = new JButton("White");
        whiteButton.setBackground(Color.WHITE);
        whiteButton.addActionListener(this);
        buttonPanel.add(whiteButton);

        grayButton = new JButton("Gray");
        grayButton.setBackground(Color.GRAY);
        grayButton.addActionListener(this);
        buttonPanel.add(grayButton);

        add(buttonPanel, BorderLayout.SOUTH);
    }

    // one ActionListener for all the buttons
    public void actionPerformed(ActionEvent e)
    {
        // determine which button was the event source
        if (e.getSource() == greenButton)
             greenPanel.setBackground(Color.GREEN);
        else if (e.getSource() == whiteButton)
            whitePanel.setBackground(Color.WHITE);
        else if (e.getSource() == grayButton)
            grayPanel.setBackground(Color.GRAY);
        else
            System.out.println("Unexpected error.");
    }
}