将单个侦听器链接到多个按钮

Question

您好，我在将单个侦听器链接到多个按钮时遇到问题。我正在尝试使用内部类，但似乎我在某处弄错了。有人可以指出我正确的方向吗？ 如果它有助于自动更正的东西（ :D ）指向第 59 行说：

“createChampButton 无法解析为变量”

代码：

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




public class GUI extends JApplet{



    public void init(){
        Container guiContainer = getContentPane();
        LayoutManager layout = new FlowLayout();
        guiContainer.setLayout(layout);


        //Create Championship Button
        final JButton createChampButton = new JButton("Create Championship");
        guiContainer.add(createChampButton);



        //Create Club Button
        final JButton createClubButton = new JButton ("Create Club");
        guiContainer.add(createClubButton);


        //Create Athlete Button
        final JButton createAthleteButton = new JButton ("Create Athlete");
        guiContainer.add(createAthleteButton);


        //Print Athletes Button
        final JButton printAthletesButton = new JButton ("Print all Athletes");
        guiContainer.add(printAthletesButton);


        //The quiet Listener
        ButtonListener aListener = new ButtonListener();
        printAthletesButton.addActionListener(aListener);
        createAthleteButton.addActionListener(aListener);
        createClubButton.addActionListener(aListener);
        createChampButton.addActionListener(aListener);

    }

     class ButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent event){
            JButton button = (JButton) event.getSource();
            //if (button.equals(printAthletesButton)){
                //JOptionPane.showMessageDialog(null, "Athlete name is: " +anAthlete.GetAthleteName());
            //  JOptionPane.showMessageDialog(null, "Athlete age is: " + anAthlete.GetAge());
                //}
            if(button.equals(createChampButton)){
                    Championship aChampionship = new Championship("","");
                    aChampionship.champName = JOptionPane.showInputDialog("Enter Championship Name: ");
                    aChampionship.duration = JOptionPane.showInputDialog("Enter Championship Duration: ");
            }       
        }
    }
}

提前致谢， 克里斯

Answer 1

createChampButton是init()中的一个局部变量

要在其他地方访问它，您需要将其更改为类中的一个字段。

Answer 2

createChampButton 未在您的其他方法中定义，因此您无法访问该范围。我看到了三种解决方法：

1) 您使用 component.getActionCommand() 代替 - 您可以将其与您的 JButton 包含的文本进行比较（类似于 if( evt.getSource().getActionCommand().equals("Create Championship")

2) 你可以在你的 init 方法中定义你的 ActionListener：

public void init(){
    Container guiContainer = getContentPane();
    LayoutManager layout = new FlowLayout();
    guiContainer.setLayout(layout);


    //Create Championship Button
    final JButton createChampButton = new JButton("Create Championship");
    guiContainer.add(createChampButton);



    //Create Club Button
    final JButton createClubButton = new JButton ("Create Club");
    guiContainer.add(createClubButton);


    //Create Athlete Button
    final JButton createAthleteButton = new JButton ("Create Athlete");
    guiContainer.add(createAthleteButton);


    //Print Athletes Button
    final JButton printAthletesButton = new JButton ("Print all Athletes");
    guiContainer.add(printAthletesButton);


    //The quiet Listener
    ActionListener aListener = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent event){
            JButton button = (JButton) event.getSource();
            //if (button.equals(printAthletesButton)){
                //JOptionPane.showMessageDialog(null, "Athlete name is: " +anAthlete.GetAthleteName());
            //  JOptionPane.showMessageDialog(null, "Athlete age is: " + anAthlete.GetAge());
                //}
            if(button.equals(createChampButton)){
                    Championship aChampionship = new Championship("","");
                    aChampionship.champName = JOptionPane.showInputDialog("Enter Championship Name: ");
                    aChampionship.duration = JOptionPane.showInputDialog("Enter Championship Duration: ");
            }       
        }
    };
    printAthletesButton.addActionListener(aListener);
    createAthleteButton.addActionListener(aListener);
    createClubButton.addActionListener(aListener);
    createChampButton.addActionListener(aListener);

}

}

3) 您将 JComponents 定义为实例变量 - 在您的 init() 方法之外声明它们（但仍然在内部分配它们）

问候，
丹尼尔