File MoveCircle.java contains a program that uses CirclePanel.java to draw a circle and let the user move it by pressing buttons.

1. Modify CirclePanel so that in addition to moving the circle, the user can press a button to change its color. The color buttons should be on the top of the panel; have four color choices. 2. Set the background or text (you choose) of each button to be the color that it represents. 3. Add another button to the top that says Choose Color. Place the button in the middle of your other color buttons. When pressed, this button should bring up a JColorChooser, and the circle color should become the color that the user chooses.

// ****************************************************************** // MoveCircle.java // // Uses CirclePanel to display a GUI that lets the user move // a circle by pressing buttons. // ****************************************************************** import java.awt.*; import javax.swing.*; public class MoveCircle { //----------------------------------- // Set up a frame for the GUI. //----------------------------------- public static void main(String[] args) { JFrame frame = new JFrame ("MoveCircle"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setPreferredSize(new Dimension(400,300)); frame.getContentPane().add(new CirclePanel(400,300)); frame.pack(); frame.setVisible(true); } }

// ****************************************************************** // CirclePanel.java // // A panel with a circle drawn in the center and buttons on the // bottom that move the circle. // ****************************************************************** import java.awt.*; import javax.swing.*; import java.awt.event.*; public class CirclePanel extends JPanel { private final int CIRCLE_SIZE = 50; private int x,y; private Color c; //---------------------------------------------------------------- // Set up circle and buttons to move it. //---------------------------------------------------------------- public CirclePanel(int width, int height) { // Set coordinates so circle starts in middle x = (width/2)-(CIRCLE_SIZE/2); y = (height/2)-(CIRCLE_SIZE/2); c = Color.green; // Need a border layout to get the buttons on the bottom this.setLayout(new BorderLayout()); // Create buttons to move the circle JButton left = new JButton("Left"); JButton right = new JButton("Right"); JButton up = new JButton("Up"); JButton down = new JButton("Down"); // Add listeners to the buttons left.addActionListener(new MoveListener(-20,0)); right.addActionListener(new MoveListener(20,0)); up.addActionListener(new MoveListener(0,-20)); down.addActionListener(new MoveListener(0,20)); // Need a panel to put the buttons on or they'll be on // top of each other. JPanel buttonPanel = new JPanel(); buttonPanel.add(left); buttonPanel.add(right); buttonPanel.add(up); buttonPanel.add(down); // Add the button panel to the bottom of the main panel // Add the button panel to the bottom of the main panel this.add (buttonPanel, " South") ; } //---------------------------------------------------------------- // Draw circle on CirclePanel //---------------------------------------------------------------- public void paintComponent(Graphics page) { super.paintComponent(page) ; page.setColor(c) ; page.fillOval(x,y,CIRCLE_SIZE,CIRCLE_SIZE) ; } //---------------------------------------------------------------- // Class to listen for button clicks that move circle. //---------------------------------------------------------------- private class MoveListener implements ActionListener { private int dx; private int dy; //-------------------------------------------------------------- // Parameters tell how to move circle at click. //-------------------------------------------------------------- public MoveListener(int dx, int dy) { this.dx = dx ; this.dy = dy; } //-------------------------------------------------------------- // Change x and y coordinates and repaint. //-------------------------------------------------------------- public void actionPerformed(ActionEvent e) { x += dx; y += dy; repaint(); } } }