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问按钮ActionListener
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Stack Overflow用户

提问于 2014-08-18 02:28:26

回答 3查看 2.3K关注 0票数 2

因此，我已经为我的一个类开发了一个程序，在单击按钮时使用ActionListener来处理事件。我有程序工作，然而，当点击任何按钮，你必须点击输入按钮多次的答案，以登记和移动到程序的下一个层次。

example1:警报按钮打开2，有时是3“嘿，你身上有个bug！”消息对话框。

example2:是/否提示你3-4次向txt返回“是/否”。

example3:在返回输入到txt之前，颜色需要点击3/4。

(我想你明白了.)

为了我的生命，我不知道为什么它不会只需要一个输入就能继续前进.

我的程序代码供你复习..。谢谢你的进阶。

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


public class MessageBoxes{

  private JButton alert = new JButton("Alert");
  private JButton yesNo = new JButton("Yes/No");
  private JButton color = new JButton("Color");
  private JButton vals = new JButton("3 Vals");
  private JButton input = new JButton("Input");

  private JTextField txt = new JTextField(15);

  private JFrame frame;

  private ActionListener al = new ActionListener(){
    public void actionPerformed(ActionEvent e){

    alert.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e)
        {
            //Execute when button is pressed
            JOptionPane.showMessageDialog(null,
                                  "There's a bug on you!", "Hey!",
                                  JOptionPane.ERROR_MESSAGE);
        }
    });  

    yesNo.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e)
        {
            //Execute when button is pressed
            int val = JOptionPane.showConfirmDialog(null,
                                  "Choose yes or no", "Your Call...",
                                  JOptionPane.YES_NO_OPTION);

            if(val != JOptionPane.CLOSED_OPTION){
              if(val == 0){
                txt.setText("Yes");
            }
            else{
                txt.setText("No");
            }
            }
        }
    });  

    color.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e)
        {
            //Execute when button is pressed
            Object[] options = {"Red", "Green"};

            int sel = JOptionPane.showOptionDialog(null,
                            "Choose a Color!", "Warning",
                            JOptionPane.DEFAULT_OPTION,
                            JOptionPane.WARNING_MESSAGE, null,
                                        options, options[0]);

            if(sel != JOptionPane.CLOSED_OPTION){
                txt.setText("Color Selected: " + options[sel]);
            }
        }
    });  

    vals.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e)
        {
            //Execute when button is pressed
            Object[] selections = {"First", "Second", "Third"};

            Object val = JOptionPane.showInputDialog(null,
                                             "Choose one", "Input",
                                             JOptionPane.INFORMATION_MESSAGE,
                                             null, selections, selections[0]);

            if(val != null){
                txt.setText(val.toString());
            }
        }
    });

    input.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e)
        {
            //Execute when button is pressed
            String val = JOptionPane.showInputDialog("How mant fingers do you see?");

                txt.setText(val);
        }
    });  
  }
  };



  public MessageBoxes(){

    frame = new JFrame("Title");

    frame.setSize(250, 250);

    frame.getContentPane().setLayout(new FlowLayout());

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.getContentPane().add(alert);
    frame.getContentPane().add(yesNo);
    frame.getContentPane().add(color);
    frame.getContentPane().add(vals);
    frame.getContentPane().add(input);
    frame.getContentPane().add(txt);

    frame.setVisible(true);

  }

  public void launchJFrame(){

    alert.addActionListener(al);
    yesNo.addActionListener(al);
    color.addActionListener(al);
    vals.addActionListener(al);
    input.addActionListener(al);

}

 public static void main(String [] args){

    MessageBoxes messageBoxes = new MessageBoxes();
    messageBoxes.launchJFrame();
 }
}

java

swing

jframe

actionlistener

回答 3

Stack Overflow用户

回答已采纳

发布于 2014-08-18 02:47:43

问题是，每次在您的actionPerformed中调用ActionListener al时，它都会使用您的按钮注册新的ActionListener。

private ActionListener al = new ActionListener() {
    public void actionPerformed(ActionEvent e) {

        alert.addActionListener(new ActionListener() {
            //...
        });

        yesNo.addActionListener(new ActionListener() {
            //...
        });

        color.addActionListener(new ActionListener() {
            //...
        });

        vals.addActionListener(new ActionListener() {
            //...
        });

        input.addActionListener(new ActionListener() {
            //...
        });
    }
};

因此，每次调用actionPerformed方法时，每个按钮都会注册一个新的actionListener。

相反，您可以使用if-else语句来确定事件的源，例如.

Object source = e.getSource();
if (source == alert) {
    JOptionPane.showMessageDialog(null,
                    "There's a bug on you!", "Hey!",
                    JOptionPane.ERROR_MESSAGE);
} else if (...

或者您可以完全摆脱ActionListener al，简单地将单个ActionListener注册到launchJFrame方法中的按钮.

public void launchJFrame() {

    alert.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            //Execute when button is pressed
        }
    });

    yesNo.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            //Execute when button is pressed
            int val = JOptionPane.showConfirmDialog(null,
                            "Choose yes or no", "Your Call...",
                            JOptionPane.YES_NO_OPTION);

            if (val != JOptionPane.CLOSED_OPTION) {
                if (val == 0) {
                    txt.setText("Yes");
                } else {
                    txt.setText("No");
                }
            }
        }
    });

    color.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            //Execute when button is pressed
            Object[] options = {"Red", "Green"};

            int sel = JOptionPane.showOptionDialog(null,
                            "Choose a Color!", "Warning",
                            JOptionPane.DEFAULT_OPTION,
                            JOptionPane.WARNING_MESSAGE, null,
                            options, options[0]);

            if (sel != JOptionPane.CLOSED_OPTION) {
                txt.setText("Color Selected: " + options[sel]);
            }
        }
    });

    vals.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            //Execute when button is pressed
            Object[] selections = {"First", "Second", "Third"};

            Object val = JOptionPane.showInputDialog(null,
                            "Choose one", "Input",
                            JOptionPane.INFORMATION_MESSAGE,
                            null, selections, selections[0]);

            if (val != null) {
                txt.setText(val.toString());
            }
        }
    });

    input.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            //Execute when button is pressed
            String val = JOptionPane.showInputDialog("How mant fingers do you see?");

            txt.setText(val);
        }
    });

}

票数 3

Stack Overflow用户

发布于 2014-08-18 02:47:41

这是因为您的actionlistener构造/添加嵌套在另一个actionlistener中，al。因此，您所关心的actionlisteners (弹出消息的那些)实际上不会添加到按钮中，直到您单击它们一次。在launchJFrame()中将actionlisteners添加到按钮中可以解决这个问题。下面是您的代码的固定版本：

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


public class MessageBoxes{

  private JButton alert = new JButton("Alert");
  private JButton yesNo = new JButton("Yes/No");
  private JButton color = new JButton("Color");
  private JButton vals = new JButton("3 Vals");
  private JButton input = new JButton("Input");

  private JTextField txt = new JTextField(15);

  private JFrame frame;

  public MessageBoxes(){

    frame = new JFrame("Title");

    frame.setSize(250, 250);

    frame.getContentPane().setLayout(new FlowLayout());

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.getContentPane().add(alert);
    frame.getContentPane().add(yesNo);
    frame.getContentPane().add(color);
    frame.getContentPane().add(vals);
    frame.getContentPane().add(input);
    frame.getContentPane().add(txt);

    frame.setVisible(true);

  }

  public void launchJFrame(){

      alert.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e)
            {
                //Execute when button is pressed
                JOptionPane.showMessageDialog(null,
                                      "There's a bug on you!", "Hey!",
                                      JOptionPane.ERROR_MESSAGE);
            }
        });  

        yesNo.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e)
            {
                //Execute when button is pressed
                int val = JOptionPane.showConfirmDialog(null,
                                      "Choose yes or no", "Your Call...",
                                      JOptionPane.YES_NO_OPTION);

                if(val != JOptionPane.CLOSED_OPTION){
                  if(val == 0){
                    txt.setText("Yes");
                }
                else{
                    txt.setText("No");
                }
                }
            }
        });  

        color.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e)
            {
                //Execute when button is pressed
                Object[] options = {"Red", "Green"};

                int sel = JOptionPane.showOptionDialog(null,
                                "Choose a Color!", "Warning",
                                JOptionPane.DEFAULT_OPTION,
                                JOptionPane.WARNING_MESSAGE, null,
                                            options, options[0]);

                if(sel != JOptionPane.CLOSED_OPTION){
                    txt.setText("Color Selected: " + options[sel]);
                }
            }
        });  

        vals.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e)
            {
                //Execute when button is pressed
                Object[] selections = {"First", "Second", "Third"};

                Object val = JOptionPane.showInputDialog(null,
                                                 "Choose one", "Input",
                                                 JOptionPane.INFORMATION_MESSAGE,
                                                 null, selections, selections[0]);

                if(val != null){
                    txt.setText(val.toString());
                }
            }
        });

        input.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e)
            {
                //Execute when button is pressed
                String val = JOptionPane.showInputDialog("How mant fingers do you see?");

                    txt.setText(val);
            }
        });  

}

 public static void main(String [] args){

    MessageBoxes messageBoxes = new MessageBoxes();
    messageBoxes.launchJFrame();
 }
}

票数 3

Stack Overflow用户

发布于 2014-08-18 03:00:47

以下是我发现的最适合我的解决方案：

private ActionListener alertAction = new ActionListener(){
  public void actionPerformed(ActionEvent e){
    //Execute when button is pressed
            JOptionPane.showMessageDialog(null,
                                  "There's a bug on you!", "Hey!",
                                  JOptionPane.ERROR_MESSAGE);
}
};

private ActionListener yesNoAction = new ActionListener(){
  public void actionPerformed(ActionEvent e){
    //Execute when button is pressed
            //Execute when button is pressed
            int val = JOptionPane.showConfirmDialog(null,
                                  "Choose yes or no", "Your Call...",
                                  JOptionPane.YES_NO_OPTION);

            if(val != JOptionPane.CLOSED_OPTION){
              if(val == 0){
                txt.setText("Yes");
            }
            else{
                txt.setText("No");
            }
            }
}
};

private ActionListener colorAction = new ActionListener(){
  public void actionPerformed(ActionEvent e){
    //Execute when button is pressed
            Object[] options = {"Red", "Green"};

            int sel = JOptionPane.showOptionDialog(null,
                            "Choose a Color!", "Warning",
                            JOptionPane.DEFAULT_OPTION,
                            JOptionPane.WARNING_MESSAGE, null,
                                        options, options[0]);

            if(sel != JOptionPane.CLOSED_OPTION){
                txt.setText("Color Selected: " + options[sel]);
            }
}
};

private ActionListener valsAction = new ActionListener(){
  public void actionPerformed(ActionEvent e){
    //Execute when button is pressed
            Object[] selections = {"First", "Second", "Third"};

            Object val = JOptionPane.showInputDialog(null,
                                             "Choose one", "Input",
                                             JOptionPane.INFORMATION_MESSAGE,
                                             null, selections, selections[0]);

            if(val != null){
                txt.setText(val.toString());
            }
}
};

private ActionListener inputAction = new ActionListener(){
  public void actionPerformed(ActionEvent e){
            //Execute when button is pressed
            String val = JOptionPane.showInputDialog("How mant fingers do you see?");

                txt.setText(val);
            }
};





public MessageBoxes(){

  frame = new JFrame("Title");

  frame.setSize(250, 250);

  frame.getContentPane().setLayout(new FlowLayout());

  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

  frame.getContentPane().add(alert);
  frame.getContentPane().add(yesNo);
  frame.getContentPane().add(color);
  frame.getContentPane().add(vals);
  frame.getContentPane().add(input);
  frame.getContentPane().add(txt);

  frame.setVisible(true);

}

public void launchJFrame(){

  alert.addActionListener(alertAction);
  yesNo.addActionListener(yesNoAction);
  color.addActionListener(colorAction);
  vals.addActionListener(valsAction);
  input.addActionListener(inputAction);

}

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/25355587

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