Actionlistener和JButton通过JLabels循环：环绕？

Question

我主要想到了这一点：分配的目的是让四个不同的广告循环通过，当你点击下一个按钮，当你到达第4号，回到第1号。我不知道为什么它不是缠绕回来？

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Component; 
import java.awt.Dimension; 
import java.awt.Image; 
import java.awt.LayoutManager; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.io.IOException; 
import java.net.URL; 

import javax.imageio.ImageIO; 
import javax.swing.ImageIcon; 
import javax.swing.JButton; 
import javax.swing.JLabel; 
import javax.swing.JOptionPane; 
import javax.swing.JPanel; 

public class advertisementPanel extends JPanel { 

public advertisementPanel() throws IOException{ 

    setPreferredSize(new Dimension(500, 200)); 
    URL url = new URL("http://www.geneca.com/wp-content/uploads/2013/03/mcdonalds-small-logo1.png"); 
    URL url2 = new URL("http://www.eatthis.com/uploads/wendys.jpg"); 
    URL url3 = new URL("http://www.scaredmonkeys.com/fun-images/KFC_20old_small.jpg"); 
    URL url4 = new URL("http://www.canaltagroup.com/images/aw_logo.gif"); 



    Image image = ImageIO.read(url); 
    ImageIcon myIcon = new ImageIcon(image); 
    JLabel adPicture1 = new JLabel(myIcon); 
    Image image2 = ImageIO.read(url2); 
    ImageIcon myIcon2 = new ImageIcon(image2); 
    JLabel adPicture2 = new JLabel(myIcon2); 
    Image image3 = ImageIO.read(url3); 
    ImageIcon myIcon3 = new ImageIcon(image3); 
    JLabel adPicture3 = new JLabel(myIcon3); 
    Image image4 = ImageIO.read(url4); 
    ImageIcon myIcon4 = new ImageIcon(image4); 
    JLabel adPicture4 = new JLabel(myIcon4); 

    JLabel myLabel1 = new JLabel("McDonald's"); 
    JLabel myLabel2 = new JLabel("20% off!"); 
    JLabel myLabel3 = new JLabel("Wendy's"); 
    JLabel myLabel4 = new JLabel("50% off!"); 
    JLabel myLabel5 = new JLabel("KFC's"); 
    JLabel myLabel6 = new JLabel("90% off!"); 
    JLabel myLabel7 = new JLabel("A&W's"); 
    JLabel myLabel8 = new JLabel("10% off!"); 

    JButton button = new JButton("next"); 

    setBackground(Color.white); 
    add(adPicture1); 
    add(myLabel1); 
    add(myLabel2); 


    button.addActionListener(new ActionListener(){ 
     public void actionPerformed(ActionEvent myEvent) { 


      if (getBackground() == Color.white) { 
       setBackground(Color.green); 
       myLabel1.setVisible(false); 
       myLabel2.setVisible(false); 
       adPicture1.setVisible(false); 
       add(myLabel3); 
       add(myLabel4); 
       add(adPicture2); 


      } else if (getBackground() == Color.green) { 

       setBackground(Color.red); 
       myLabel3.setVisible(false); 
       myLabel4.setVisible(false); 
       adPicture2.setVisible(false); 
       add(myLabel5); 
       add(myLabel6); 
       add(adPicture3); 

      } else if (getBackground() == Color.red) { 

       setBackground(Color.pink); 
       myLabel5.setVisible(false); 
       myLabel6.setVisible(false); 
       adPicture3.setVisible(false); 
       add(myLabel7); 
       add(myLabel8); 
       add(adPicture4); 

      } else if (getBackground() == Color.pink) { 

       myLabel7.setVisible(false); 
       myLabel8.setVisible(false); 
       adPicture4.setVisible(false); 
       add(myLabel1); 
       add(myLabel2); 
       add(adPicture1); 
       setBackground(Color.white); 

      } 

      } 


     }); 
     add(button); 

    } 

} 

Answer 1

你可能不想add()标签和图片各按钮被点击的时间。也就是说，他们可能被添加，但旧的不会被删除。所以它们被添加到其可见区域之外的面板。

单击按钮而不是添加新标签时，可以更改标签的文本和图标。