Java 静态JFrame ActionListener

在这段代码中，我为什么要

private STATIC int？？？

哪种方法是静态的

如果我没有静态编译它，它会在

MyAppEv app=newmyappev（“皇家马德里”+g+：“+h+”巴塞罗那”）中出错

有人能给我解释一下JFrame和Actionlistener吗？
在上面的代码中使用
static
的唯一原因是因为您从
static
上下文中设置了标题

相反，您不能在构造函数中获取应用程序标题的值，而只是创建一个更新框架标题的
updateTitle
方法

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

public class MyAppEv extends JFrame implements ActionListener {

    private static int h = 0, g = 0;
    JButton b1 = new JButton("Real");
    JButton b2 = new JButton("Barcelona");

    public MyAppEv(String title) {
        super(title);

        b1.addActionListener(this);
        b2.addActionListener(this);

        JPanel myPanel = new JPanel();
        myPanel.add(b1);
        myPanel.add(b2);
        setContentPane(myPanel);
    }

    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if (source == b1) {
            ++g;
            setTitle("Real Madrid " + g + ":" + h + " Barcelona");
        } else if (source == b2) {
            ++h;
            setTitle("Real Madrid " + g + ":" + h + " Barcelona");
        }
    }

    public static void main(String[] args) {

        try {

            UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
        } catch (Exception e) {
            System.err.println("Can't set look and feel: " + e);
        }
        MyAppEv app = new MyAppEv("Real Madrid " + g + ":" + h + " Barcelona");
        WindowListener L = new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        };
        app.addWindowListener(L);
        app.setBounds(300, 200, 350, 250);

        app.setVisible(true);
    }
}

事实上，对于您试图实现的目标，我将避免使用
静态
，因为如果每个JVM有多个帧的一个实例，这将产生影响

如果您想提供一个标题并对其进行更新，您可以覆盖
setTitle
方法并附加其他内容，例如

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

public class MyAppEv extends JFrame implements ActionListener {

    private int h = 0, g = 0;
    JButton b1 = new JButton("Real");
    JButton b2 = new JButton("Barcelona");

    public MyAppEv() {
        updateTitle();

        b1.addActionListener(this);
        b2.addActionListener(this);

        JPanel myPanel = new JPanel();
        myPanel.add(b1);
        myPanel.add(b2);
        setContentPane(myPanel);
    }

    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if (source == b1) {
            ++g;
            updateTitle();
        } else if (source == b2) {
            ++h;
            updateTitle();
        }
    }

    protected void updateTitle() {
        setTitle("Real Madrid " + g + ":" + h + " Barcelona");
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }
                MyAppEv app = new MyAppEv();
                WindowListener L = new WindowAdapter() {
                    public void windowClosing(WindowEvent e) {
                        System.exit(0);
                    }
                };
                app.addWindowListener(L);
                app.setBounds(300, 200, 350, 250);

                app.setVisible(true);
            }
        });
    }
}

你不能不知道如何拼写你要问的Java关键字。在问新问题之前，先接受前面问题的答案。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class MyAppEv extends JFrame implements ActionListener {

    private int h = 0, g = 0;
    private String realTitle;
    JButton b1 = new JButton("Real");
    JButton b2 = new JButton("Barcelona");

    public MyAppEv(String title) {
        // super(title) won't call setTitle and the
        // the method used is to initialise the title 
        // is private...awesome...
        setTitle(title);

        b1.addActionListener(this);
        b2.addActionListener(this);

        JPanel myPanel = new JPanel();
        myPanel.add(b1);
        myPanel.add(b2);
        setContentPane(myPanel);
    }

    @Override
    public void setTitle(String title) {
        System.out.println("Real title = " + title);
        realTitle = title;
        if (title == null) {
            title = "";
        }
        super.setTitle(title + ": Real Madrid " + g + ":" + h + " Barcelona"); 
    }
    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if (source == b1) {
            ++g;
            updateTitle();
        } else if (source == b2) {
            ++h;
            updateTitle();
        }
    }

    protected void updateTitle() {
        setTitle(realTitle);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }
                MyAppEv app = new MyAppEv("This is an example title");
                WindowListener L = new WindowAdapter() {
                    public void windowClosing(WindowEvent e) {
                        System.exit(0);
                    }
                };
                app.addWindowListener(L);
                app.setBounds(300, 200, 350, 250);

                app.setVisible(true);
            }
        });
    }
}