Question

我是Java新手，我有一个问题。

我有一个扩展JPanel的课程。它包含JButton。如果我按下这个按钮，我想让另一个班级注意到这一点。通过这样做，我读过我必须使用Observer/Observable。

唯一的问题是，我只能延长一次..有什么建议吗？

这两个类：

public class ControlsPanel extends JPanel{

    private JButton start;
    private JButton stop;
    private int animationSpeed = 5;
    private boolean startIsPressed;
    private CashRegistersPanel cr_panel;

    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;
            }

            }
        });

        //For the STOP BUTTON
        stop.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                if (stop.isEnabled()) {
                    stop.setEnabled(false);
                    start.setText("Start");
                    startIsPressed = false;
                }
            }
        });
    }

    public boolean StartisPressed() {
        return startIsPressed;
    }
}

和

public class CashRegistersPanel extends JPanel{

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


    private ArrayList<CashRegister> myRegister = new ArrayList<CashRegister>();

    public CashRegistersPanel(ParametersPanel parametersPanel, ControlsPanel controlPanel) {

        startIsPressed = controlsPanel.StartisPressed();
    }


    public void paintComponent(Graphics g) {
        if (startIsPressed) {
        Need to do the painting here
        }
        }
    }
}

Answer 1

您可以在类中实现ActionListener，假设MyPanel正在扩展JPanel。然后，您可以在按钮的ActionListener中传递MyPanel的对象。

class MyPanel extends JPanel implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent e) {
       // Your Drawing Code
    }
    //your other jpanel code
}

创建自定义JPanel的对象

 MyPanel myPanel1;

现在您可以将myPanel1对象作为按钮的ActionListener传递。

button.addActionListener(myPanel1);

Answer 2

您应该向要监控的ActionListener添加Jbutton。

Answer 3

不要扩展JPanel，你应该没有一个理由。现在，如果您希望其他类注意到您应该使用控制器作为MVC模式的排序版本。

扩展JPanel和observable

3 个答案: