package paint.lzj; import java.awt.BorderLayout;import java.awt.Color;import java.awt.event.ActionEvent;import java.awt.event.ActionListener; import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JPanel; @SuppressWarnings("serial")public class ActionListener_1 extends JFrame implements ActionListener{ //mb3 mb=null; JPanel p2=null; JButton b1,b2; @SuppressWarnings("deprecation") public ActionListener_1(){ this.setSize(500, 500); this.setLocation(200, 200); JPanel p1=new JPanel(); //mb3 mb=new mb3(); JPanel p2=new JPanel(); JPanel p3=new JPanel(); JButton b1=new JButton("紅色"); JButton b2=new JButton("黃色"); p1.add(b1); //mb.setBackground(Color.BLUE); p2.setBackground(Color.BLUE); p3.add(b2); this.add(p1, BorderLayout.NORTH); //this.add(mb, BorderLayout.CENTER); this.add(p2, BorderLayout.CENTER); this.add(p3, BorderLayout.SOUTH); b1.addActionListener(this); b1.setActionCommand("111"); b2.addActionListener(this); b2.setActionCommand("222"); this.show(); this.setDefaultCloseOperation(EXIT_ON_CLOSE); } public static void main(String[] args) { // TODO 自動(dòng)生成的方法存根 @SuppressWarnings("unused") ActionListener_1 aa=new ActionListener_1(); } @Override public void actionPerformed(ActionEvent e) { // TODO 自動(dòng)生成的方法存根 //System.out.println("按鈕起作用了"); if(e.getActionCommand().equals("111")){ //mb.setBackground(Color.RED); //System.out.println("a按鈕起作用了"); p2.setBackground(Color.RED); } else if(e.getActionCommand().equals("222")){ //mb.setBackground(Color.YELLOW); //System.out.println("b按鈕起作用了"); p2.setBackground(Color.YELLOW); } }} 上面的代碼可以出現(xiàn)窗口但是執(zhí)行不了監(jiān)聽(tīng)里的p2.setBackground(Color.RED);p2.setBackground(Color.YELLOW); 這兩行代碼