java创建类的独立对象

Question

我想创建一个类中多个相互独立的对象

我在for循环中多次调用类构造函数，但如何识别这些对象呢

我尝试使用一个静态变量来获取for循环索引的值，但是这个变量假定for循环的最后一个索引的值

以下是代码：

美因圭。爪哇

public class Maingui extends JFrame {

    public static JFrame frame;
    public static JButton runButton;

    public Maingui() throws IOException {

        frame = new JFrame("maingui");
        setSize(1024,700);
        setTitle("maingui");
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);

        setLayout(new BorderLayout());

        runButton = new JButton("Run");
        runButton.addActionListener(new RunBtnListener());
        add(runButton);

    }
}

RunBtnListener。爪哇

public class RunBtnListener implements ActionListener {

    ArrayList<SecondGui> menus = new ArrayList<SecondGui>();

    public void actionPerformed(ActionEvent e) {

        for(int i = 0; i < 2; i++) {

            menus.add(new SecondGui(i));

        }

    }

}

第二个GUI。爪哇

public class SecondGui extends JFrame {

    public static int c;
    JFrame frame;
    JButton button;

    public SecondGui(int i) {

        this.c = i;

        frame = new JFrame("Test");
        setSize(1024,700);
        setTitle("Menu");
        setLocationRelativeTo(null);
        setVisible(true);
        this.setLocation(50*i, 50*i);

        // Set layout manager
        setLayout(new BorderLayout());

        button = new JButton("B");
        button.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("C: " + c);

            }

        });

        add(button);

    }

}

当我在SecondGuiGUI中单击按钮button时，输出总是1。 但我希望输出将是0或1基于我在哪个GUI中选择按钮

Answer 1

I want to create more than one object of a class that are independent one from the other.

当前代码在这个循环中创建了两个独立的对象

    for(int i = 0; i < 2; i++) {

        menus.add(new SecondGui(i));
    }

但是，当您将其设置为静态时，它不会绑定到您创建的任何实例

您需要的是一个实例变量来保留SecondGui实例的ID。您可以创建一个新的构造函数并传递循环的索引

public class SecondGui extends JFrame {

    private int c = 0;
    private JFrame frame;
    private JButton button;

    public SecondGui(int i) {

        this.c = i;
        initialize();
    }

    void initialize() {

        frame = new JFrame("Test");
        setSize(1024,700);
        setTitle("Menu");
        setLocationRelativeTo(null);
        setVisible(true);
        this.setLocation(50*i, 50*i);

        // Set layout manager
        setLayout(new BorderLayout());

        button = new JButton("B");
        button.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("C: " + c);

            }

        });

        add(button);
     }

}