JComboBox行动将不会执行

Question

让说用户选择加油站。该框架将改变，用户将能够选择一个位置，该位置的加油站列表将显示在组合框下方。

所以我已经尝试在if语句内添加另一个动作侦听器，使用另一个if else，并且我也尝试了switch语句，但都不会显示输出。那么我该如何解决这个问题？提前致谢。

这是我的代码的缩短版添加第二个动作监听

前

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

public class Testing5 { 
private JFrame frame1, frame2; 
private ActionListener action, action2; 
private JButton PetrolStations, back, Foods; 
private JComboBox locationChooser; 
final static String[] location = {"Petaling Jaya", "Port Klang", "Kuala Lumpur"}; 

public void HELPMEGUI() { 

    frame1 = new JFrame("Frame 1"); 
    frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  

    JPanel contentPanel = new JPanel(new GridLayout(5,2)); 

    PetrolStations = new JButton ("PetrolStations"); 
    Foods = new JButton ("Foods");  
    back = new JButton ("Back"); 

    locationChooser = new JComboBox(location); 

    action = new ActionListener() { 
     public void actionPerformed(ActionEvent ae) { 
      JButton button = (JButton) ae.getSource();   

      if (button == PetrolStations) { 
       frame2 = new JFrame("FRAME 2"); 
       frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
       frame2.add(locationChooser, BorderLayout.NORTH); 
       frame2.add(back, BorderLayout.SOUTH); 

       frame2.setSize(300, 300); 
       frame2.setLocationRelativeTo(null); 
       frame2.setVisible(true); 
       frame1.setVisible(false); 

      } 

      else if (button == Foods) { 
       frame2 = new JFrame("FRAME 2"); 
       frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
       frame2.add(locationChooser, BorderLayout.NORTH); 
       frame2.add(back, BorderLayout.SOUTH); 

       frame2.setSize(300, 300); 
       frame2.setLocationRelativeTo(null); 
       frame2.setVisible(true); 
       frame1.setVisible(false); 

      } 

      else if (button == back) { 
       frame1.setVisible(true); 
       frame2.setVisible(false); 
       frame2.dispose(); 
      } 
     } 
    }; 

    PetrolStations.addActionListener(action); 
    Foods.addActionListener(action); 
    back.addActionListener(action); 
    locationChooser.addActionListener(action2); 

    contentPanel.add(PetrolStations); 
    contentPanel.add(Foods); 

    frame1.getContentPane().add(contentPanel); 
    frame1.setSize(640, 400); 
    frame1.setVisible(true); 
    frame1.setLocationRelativeTo(null); 

} 

public static void main(String...args) { 
    SwingUtilities.invokeLater(new Runnable() 
    { 
     public void run() 
     { 
      new Testing5().HELPMEGUI(); 
     } 
    }); 
} 

} 

编辑：

这就是我试图做

action2 = new ActionListener() { 
        public void actionPerformed(ActionEvent e) { 
         JComboBox locationSelected = (JComboBox) e.getSource(); 

         if (locationSelected == Kuala Lumpur) { 
          System.out.println("Address 1"); 
         } 
        } 
       }; 

2n ð尝试

action2 = new ActionListener() { 
        public void actionPerformed(ActionEvent e) { 
        int temp; 

        if(e.getSource() == locationChooser) { 
         temp = locationChooser.getSelectedIndex(); 

         switch (temp) { 
         case 0: System.out.println("Address 1"); break; 
         case 1: System.out.println("Address 2"); break; 
         } 
        } 
        } 
        };} 

Answer 1

你不显示你的行动侦听器定义的范围内，所以我想你可能有它在错误的地方。以下是我做到了，而且似乎工作：

PetrolStations.addActionListener(action); 
    Foods.addActionListener(action); 
    back.addActionListener(action); 
    action2 = new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 
      int temp; 

      if (e.getSource() == locationChooser) { 
       temp = locationChooser.getSelectedIndex(); 

       switch (temp) { 
        case 0: 
         System.out.println("Address 1"); 
         break; 
        case 1: 
         System.out.println("Address 2"); 
         break; 
       } 
      } 
     } 
    }; 
    locationChooser.addActionListener(action2);