textsetForeground(cr): btn[2].addActionListener(new ActionListener( public daction log(nul,"调色板"，Color.red) contentPane..add(panel,BorderLayout NORTH):/I将面板添加到窗口北边 ee0 oid main(St 4、(25分)参考程序 mport java.awt mport image BufferedImage. import cmmage co public class Test4 extends JFrame DrawPanel drawPanel public Test4(! super("第4题") derLayout)】 drawPa (drawPanel.BorderLayout.CENTER) JMenu myMenu=buildMenu(); 单条 /创建菜单条 川设置窗口具有菜单冬 menuBar..add(myMenu),/菜单添加到莱单条 private 33 text.setForeground(cr); } }); btn[2].addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e) { Color cr=JColorChooser.showDialog(null,"调色板",Color.red); text.setBackground(cr); } }); // contentPane.add(panel,BorderLayout.NORTH);//将面板添加到窗口北边 setSize(400,300); setVisible(true); } public static void main(String args[]){ new Test3("第 3 题"); } } 4、（25 分）参考程序： import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.awt.image.BufferedImage; import java.io.*; import com.sun.image.codec.jpeg.*; public class Test4 extends JFrame{ DrawPanel drawPanel; public Test4(){ super("第 4 题"); Container contentPane = this.getContentPane(); contentPane.setLayout(new BorderLayout()); drawPanel=new DrawPanel(); contentPane.add(drawPanel,BorderLayout.CENTER); JMenu myMenu=buildMenu(); //菜单条 JMenuBar menuBar = new JMenuBar(); //创建菜单条 setJMenuBar(menuBar);//设置窗口具有菜单条 menuBar.add(myMenu); //菜单添加到菜单条 this.setSize(400,400); this.setVisible(true); } private JMenu buildMenu(){ //菜单 JMenu fileMenu = new JMenu("File"); //菜单 fileMenu.setMnemonic(KeyEvent.VK_F); //设置快捷键：ALT+'F