17.1

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

public class ButtonDemo extends JFrame{
    
    protected MessagePanel messagePanel = new MessagePanel("Welcome to Java");
    
    private JButton jbtLeft = new JButton("<=");
    private JButton jbtRight = new JButton("=>");
    
    //add color raido buttons
    ButtonGroup group = new ButtonGroup();
    JRadioButton jrb1 = new JRadioButton("red");
    JRadioButton jrb2 = new JRadioButton("blue");
    JRadioButton jrb3 = new JRadioButton("yellow");    
    
    public ButtonDemo(){
        messagePanel.setBackground(Color.white);
        
        JPanel jpButtons = new JPanel();
        jpButtons.add(jbtLeft);
        jpButtons.add(jbtRight);
        
        JPanel jgButtons = new JPanel();
        jgButtons.setLayout(new GridLayout(1,3));
        jgButtons.add(jrb1);
        jgButtons.add(jrb2);
        jgButtons.add(jrb3);
        
        group.add(jrb1);
        group.add(jrb2);
        group.add(jrb3);    
        
        
        jbtLeft.setMnemonic('L');
        jbtRight.setMnemonic('R');
        
        jbtLeft.setToolTipText("Move message to left");
        jbtRight.setToolTipText("Move message to right");
        
        setLayout(new BorderLayout());
        add(jgButtons,BorderLayout.NORTH);
        add(messagePanel,BorderLayout.CENTER);
        add(jpButtons,BorderLayout.SOUTH);
        
        jbtLeft.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                messagePanel.moveLeft();
            }
            
        });
        jbtRight.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                messagePanel.moveRight();
            }
            
        });
        jrb1.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO Auto-generated method stub
                messagePanel.setColor(Color.RED);
            }
            
        });
        jrb2.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO Auto-generated method stub
                messagePanel.setColor(Color.BLUE);
            }
            
        });
        jrb3.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO Auto-generated method stub
                messagePanel.setColor(Color.YELLOW);
            }
            
        });
    }
    
    public static void main(String[] args){
        ButtonDemo frame = new ButtonDemo();
        frame.setTitle("ButtonDemo");
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

// MessagePanel.java: Display a message on a JPanel
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JPanel;

public class MessagePanel extends JPanel {
  /** The message to be displayed */
  private String message = "Welcome to Java";

  /** The x coordinate where the message is displayed */
  private int xCoordinate = 20;

  /** The y coordinate where the message is displayed */
  private int yCoordinate = 20;

  /** Indicate whether the message is displayed in the center */
  private boolean centered;

  /** The interval for moving the message horizontally and vertically */
  private int interval = 10;

  private Color myColor = Color.BLACK;
  /** Default constructor */
  public MessagePanel() {
  }

  /** Constructor with a message parameter */
  public MessagePanel(String message) {
    this.message = message;
  }

  /** Return message */
  public String getMessage() {
    return message;
  }

  /** Set a new message */
  public void setMessage(String message) {
    this.message = message;
    repaint();
  }

  /** Return xCoordinator */
  public int getXCoordinate() {
    return xCoordinate;
  }

  /** Set a new xCoordinator */
  public void setXCoordinate(int x) {
    this.xCoordinate = x;
    repaint();
  }

  /** Return yCoordinator */
  public int getYCoordinate() {
    return yCoordinate;
  }

  /** Set a new yCoordinator */
  public void setYCoordinate(int y) {
    this.yCoordinate = y;
    repaint();
  }

  /** Return centered */
  public boolean isCentered() {
    return centered;
  }

  /** Set a new centered */
  public void setCentered(boolean centered) {
    this.centered = centered;
    repaint();
  }

  /** Return interval */
  public int getInterval() {
    return interval;
  }

  /** Set a new interval */
  public void setInterval(int interval) {
    this.interval = interval;
    repaint();
  }

  /** Paint the message */
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);

    if (centered) {
      // Get font metrics for the current font
      FontMetrics fm = g.getFontMetrics();

      // Find the center location to display
      int stringWidth = fm.stringWidth(message);
      int stringAscent = fm.getAscent();
      // Get the position of the leftmost character in the baseline
      xCoordinate = getWidth() / 2 - stringWidth / 2;
      yCoordinate = getHeight() / 2 + stringAscent / 2;
    }
    g.setColor(myColor);
    g.drawString(message, xCoordinate, yCoordinate);
  }

  /** Move the message left */
  public void moveLeft() {
    xCoordinate -= interval;
    repaint();
  }

  /** Move the message right */
  public void moveRight() {
    xCoordinate += interval;
    repaint();
  }

  /** Move the message up */
  public void moveUp() {
    yCoordinate -= interval;
    repaint();
  }

  /** Move the message down */
  public void moveDown() {
    yCoordinate -= interval;
    repaint();
  }

  /** Override get method for preferredSize */
  public Dimension getPreferredSize() {
    return new Dimension(200, 30);
  }
  
  public void setColor(Color color){
      this.myColor = color;
      repaint();
  }
}

效果图：