Question

我已经为此工作了两天，但我仍然无法弄明白。所以我有这些课程：

MyContentPane
ParametersPanel
ControlsPanel

第一堂课如下：

public class MyContentPane extends JPanel{

private ParametersPanel parametersPanel;
private ControlsPanel controlPanel;
private CashRegistersPanel cashRegistersPanel;

public MyContentPane() {

    parametersPanel = new ParametersPanel();
    controlPanel = new ControlsPanel(parametersPanel);
    cashRegistersPanel = new CashRegistersPanel();

    this.setLayout(null);
    this.add(controlPanel);
    this.add(parametersPanel);
    this.add(cashRegistersPanel);

    controlPanel.setBounds(0, 0, 300, 250);
    parametersPanel.setBounds(0, 250, 300, 450);
    cashRegistersPanel.setBounds(300, 0, 1500, 700);

    this.setPreferredSize(new Dimension(1800,700));

}

}

第二堂课如下：

public class ParametersPanel extends JPanel{

private ControlsPanel controlsPanel;

private JButton reset;

public ParametersPanel() {

    controlsPanel = new ControlsPanel(this);


    this.setBackground(new Color(219,221,255));

    reset       = new JButton("Reset parameters");

    reset.setFont(new Font("Arial", Font.BOLD, 14));

    this.setLayout(null);


    this.add(reset);

    reset.setBounds(10, 245, 280, 30);



    reset.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent arg0) {
            boolean startIsPressed = controlsPanel.StartisPressed();
            System.out.println("Boolean: " + startIsPressed);
        }
    });

}

最后一堂课是：

public class ControlsPanel extends JPanel{

private JButton start;
private JButton stop;

private boolean startIsPressed;

public ControlsPanel(final ParametersPanel panel) {

    start       = new JButton("Start");
    stop        = new JButton("Stop");

    start.setFont(new Font("Arial", Font.BOLD, 14));
    stop.setFont(new Font("Arial", Font.BOLD, 14));

    this.setLayout(null);
    this.setBackground(new Color(199,202,255));

    this.add(start);
    this.add(stop);


    start.setBounds(10, 10, 280, 30);
    stop.setBounds(10, 50, 280, 30);

    stop.setEnabled(false);


    start.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent arg0) {

        if (start.getText().equals("Start")) {
            start.setText("Pause");
            stop.setEnabled(true);
            startIsPressed = true;

            System.out.println("Start Button boolean value: " + startIsPressed + stringStartIsPressed);

        }
    });

public boolean StartisPressed() {
    return startIsPressed;
}

现在的问题是，一旦按下ControlsPanel中的“开始”按钮，布尔值就会变为true。但是当我通过按下重置按钮在ParametersPanel中询问此布尔值时，它返回false。我发现如果我改变了第一类（MyContentPane）中面板变形的顺序，我解决了问题，但是我不能在ControlsPanel中要求布尔......

添加了另一个类

public class CashRegistersPanel extends JPanel{

private Image img;
private int amount;
private ParametersPanel parametersPanel;
private ControlsPanel controlsPanel;
private boolean startIsPressed;

public CashRegistersPanel() {

    parametersPanel = new ParametersPanel();

    startIsPressed = controlsPanel.StartisPressed();

    this.setBackground(new Color(237,237,237));
    this.setLayout(null);

    CashRegister cashRegister = new CashRegister();
    img = cashRegister.getImg();

    amount = parametersPanel.getAmountOfRegisters();


}
    public void setControlsPanel(ControlsPanel cp) {
    controlsPanel = cp;

}

我改变了你们建议的MyContentPane并添加了更多内容：

public class MyContentPane extends JPanel{

private ParametersPanel parametersPanel;
private ControlsPanel controlPanel;
private CashRegistersPanel cashRegistersPanel;

public MyContentPane() {

    parametersPanel = new ParametersPanel();
    controlPanel = new ControlsPanel(parametersPanel);
    parametersPanel.setControlsPanel(controlPanel);
    cashRegistersPanel = new CashRegistersPanel(parametersPanel, controlPanel);

谢谢你们，问题解决了！

Answer 1

您正在创建2个ControlsPanel。

不应该在ParametersPanel中创建一个，这是违规行：

controlsPanel = new ControlsPanel(this);

而是在ParametersPanel上创建一个setter方法：

public void setControlsPanel(ControlsPanel cp) {
    controlsPanel = cp;
}

并将第一个类中的初始化更改为：

parametersPanel = new ParametersPanel();
controlPanel = new ControlsPanel(parametersPanel);
parametersPanel.setControlsPanel(controlPanel); // <- new line
cashRegistersPanel = new CashRegistersPanel();

Answer 2

我希望您在MyContentPane中实例化一个ControlsPanel，但ParametersPanel会创建自己的ControlsPanel。我认为你应该将ControlsPanel传递给ParametersPanel，而不是创建一个新的new。请记住，每当您说public ParametersPanel() { controlsPanel = new ControlsPanel(this);时，您都会创建一个完全独立的对象。

改变这个：

public ParametersPanel(ControlPanel cp) {

    controlsPanel = cp;

到此：

controlPanel = new ControlsPanel();
parametersPanel = new ParametersPanel(controlPanel);

并将MyControlPanel代码更改为：

public ControlsPanel() {

和ControlsPanel构造函数：

ParametersPanel

因为您似乎没有使用startIsPressed的引用。

或者，您可以将{{1}}设置为静态变量，但我不认为这是您真正想要的。

Boolean不返回正确的值

2 个答案: