java - 如何在 JFrame 中获取事件监听器外部的变量？

Question

我想返回 count 的新值，以便下面的 while 语句可以更改标签的文本。除了这个以外，其他一切都有效。

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

public class beepBoop extends JApplet { 

    private JButton play = new JButton("Play");
    private JButton loop = new JButton("Loop");
    private JButton stop = new JButton("Stop");
    JLabel songTitle = new JLabel("Test");
    JLabel amountClicks = new JLabel();
    JLabel warning = new JLabel("KEEP ON LISTENING!!!");
    private AudioClip audioClip;

    int count = 0;

    public beepBoop() {

        audioClip = Applet.newAudioClip(getClass().getResource("song1.wav"));
        JPanel pane = new JPanel(new FlowLayout());
        JPanel panel = new JPanel();
        panel.add(play);
        panel.add(loop);
        panel.add(stop);
        panel.add(songTitle);
        panel.add(amountClicks);
        panel.add(warning);
        stop.setEnabled(false);
        add(panel, BorderLayout.CENTER);


        play.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    start();
                    songTitle.setText("LOVE THE SONG");
                    count++;
                    amountClicks.setText("You have pressed button " + count + " times.");
                }
        });
        loop.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    loop();
                    songTitle.setText("YOU REALLY LOVE THIS SONG");
                }
        });
        stop.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    stop();
                    songTitle.setText("WOW YOU ALREADY QUIT IT!!!");
                }
        });
        int countTotal = count;

        while (countTotal >= 5) {
            if (countTotal >= 5) {
                warning.setText("MAYBE YOU'VE HAD TOO MUCH!!!");
            } else if (countTotal >= 10) {
                warning.setText("YOU HAVE HAD WAYYY TO MUCH!!!");
            } else {
                warning.setText("WOW!!!");
            }
        }

    }

    public void start() {

        audioClip.play();
        play.setEnabled(false);
        stop.setEnabled(true);
        loop.setEnabled(true);       
    }

    public void loop() {
        stop();
        audioClip.loop();
        loop.setEnabled(false);
        play.setEnabled(true); 
        stop.setEnabled(true);
    }    

    public void stop() {
        audioClip.stop();
        stop.setEnabled(false);
        loop.setEnabled(true);
        play.setEnabled(true);        
    }    

    public static void main(String[] args) {

        beepBoop player = new beepBoop();

         JFrame frame = new JFrame("beepBoop");
         beepBoop applet = new beepBoop();
        applet.init();

        frame.getContentPane().add(applet, BorderLayout.CENTER);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setSize(225,275);
        frame.setVisible(true);       
    }
}

因此，回顾一下我想做的就是获取 play.addActionListener 之外的变量，以便下面的 while 语句可以在触发一定量的点击后显示正确的响应。

Answer 1

I would like to return the new value for count so that the while statement below can change the text of a label.

不，你真的不知道。严重地。这段代码:

    while (countTotal >= 5) {
        if (countTotal >= 5) {
            warning.setText("MAYBE YOU'VE HAD TOO MUCH!!!");
        } else if (countTotal >= 10) {
            warning.setText("YOU HAVE HAD WAYYY TO MUCH!!!");
        } else {
            warning.setText("WOW!!!");
        }
    }

属于线性用户界面控制台程序，在该程序中，您可以准确地知道代码流何时将进入此循环，并且当它进入时，它必须保留在循环中，直到用户完成输入数据。

但这不是 Swing(或任何使用事件驱动范例的)程序的工作方式，因为使用事件驱动代码，您无法完全控制程序流程，因为用户可以自由地与任何 GUI 交互呈现给他并启用的组件。

因此，您可能希望在某个 ActionListener 中使用计数器变量，并根据计数器变量的状态更改监听器的行为。 if/else 或 switch block 可以用于此目的。

所以，也许......

play.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start();
            songTitle.setText("LOVE THE SONG");
            count++;
            amountClicks.setText("You have pressed button " + count + " times.");

            if (countTotal >= 5) {
                warning.setText("MAYBE YOU'VE HAD TOO MUCH!!!");
            } else if (countTotal >= 10) {
                warning.setText("YOU HAVE HAD WAYYY TO MUCH!!!");
            } else {
                warning.setText("WOW!!!");
            }
        }
});