通過單擊JButton獲取JPanel-有解無憂

public class OpenFrame extends JFrame implements ActionListener {

    private static final int WIDTH = 500;
    private static final int HEIGHT = 500;
    private BudgetPlanner budgetPlanner;
    private JLabel welcomeMessage;
    private JPanel openpanel = new JPanel();

    private JButton loadButton = new JButton();
    private JButton resetButton = new JButton();
    private JFrame openFrame;
    private JLabel getWelcomeMessage;

    public BudgetPlanner callBudgetPlanner() {
        try {
            budgetPlanner = new BudgetPlanner();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        return budgetPlanner;
    }

    public OpenFrame() {
        openFrame = new JFrame();
        openFrame.setTitle("BudgetPlanner");
        openFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        openFrame.setResizable(false);
        openFrame.setLayout(null);
        openFrame.setLocationRelativeTo(null);
        openFrame.setSize(new Dimension(WIDTH, HEIGHT));
        openFrame.getContentPane().setBackground(Color.GRAY);
        openPanel();
        openFrame.setContentPane(openpanel);

        openFrame.setVisible(true);
    }

    public void openPanel() {
        openpanel.setLayout(null);

        welcomeMessage = new JLabel("Hello there! Welcome back. Choose an option below:");
        welcomeMessage.setVerticalTextPosition(TOP);
        welcomeMessage.setHorizontalTextPosition(SwingConstants.CENTER);
        welcomeMessage.setBounds(50, 20, 500, 200);
        welcomeMessage.setFont(new Font("Arial", Font.PLAIN, 17));

        openpanel.setBounds(0, 0, 500, 500);
        openpanel.add(welcomeMessage);

        loadButton.setBounds(200, 170, 100, 50);
        loadButton.setFont(new Font("Arial", Font.CENTER_BASELINE, 15));
        loadButton.setText("Load Data");
        loadButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                LoadCompletePanel loadCompletePanel = new LoadCompletePanel();
                openpanel.add(loadCompletePanel);
            }
        });
        loadButton.setFocusable(false);

        resetButton.setBounds(200, 230, 100, 50);
        resetButton.setFont(new Font("Arial", Font.CENTER_BASELINE, 15));
        resetButton.setText("Reset Data");
        resetButton.addActionListener(this);
        resetButton.setFocusable(false);

        openpanel.add(loadButton);
        openpanel.add(resetButton);
    }

以上是我的代碼，我有一個問題。我想通過單擊 loadButton 來呼叫一個新面板（在單獨的類中制作），但它似乎不起作用 - 即使我單擊該按鈕也沒有任何反應。

我應該如何解決這個問題？順便說一下，下面是新面板的代碼：

public class LoadCompletePanel extends JPanel implements ActionListener {

    private BudgetPlanner budgetPlanner;
    private JPanel loadCompletePanel;
    private JLabel loadCompleteMessage;
    private JButton addExpense;
    private JButton addIncome;
    private JButton viewMonthlyExpense;
    private JButton viewMonthlyIncome;

    public LoadCompletePanel() {
        loadCompletePanel = new JPanel();
        loadScreenPanel();
        loadCompletePanel.add(loadCompleteMessage);
        loadCompletePanel.setBounds(200, 170, 100, 50);
        setVisible(true);

    }

    private void loadScreenPanel() {
        loadCompletePanel.setLayout(null);
        loadCompleteMessage = new JLabel("Loading Complete.");
        loadCompleteMessage.setBounds(130, 50, 500, 200);

    }

對不起，如果這是一個非常瑣碎和基本的問題。我仍然是 Java 的初學者。任何幫助，將不勝感激。

uj5u.com熱心網友回復：

我終于得到了你的代碼來做你期望它做的事情。我做了一些改變。如果您想查看我所做的更改，我建議您將您的代碼與下面的代碼進行比較。但是，我建議重寫您的應用程式。我已經這樣做了，重寫應用程式的代碼出現在我修改后的代碼版本之后。

這是您問題中代碼的修改版本。
（請注意，我在您的問題中找不到 classBudgetPlanner的代碼，但由于您問題中的代碼從不呼叫 method callBudgetPlanner，我只是洗掉了該方法。我還洗掉了未使用的匯入和未使用的變數。代碼后有更多注釋。）

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;

public class OpenFrame extends JFrame implements ActionListener {
    private static final int WIDTH = 500;
    private static final int HEIGHT = 500;

    private JLabel welcomeMessage;
    private JPanel openpanel = new JPanel();

    private JButton loadButton = new JButton();
    private JButton resetButton = new JButton();
    private JFrame openFrame;

    public OpenFrame() {
        openFrame = new JFrame();
        openFrame.setTitle("BudgetPlanner");
        openFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        openFrame.setResizable(false);
        openFrame.setLayout(null);
        openFrame.setLocationRelativeTo(null);
        openFrame.setSize(new Dimension(WIDTH, HEIGHT));
        openFrame.getContentPane().setBackground(Color.GRAY);
        openPanel();
        openFrame.setContentPane(openpanel);

        openFrame.setVisible(true);
    }

    public void openPanel() {
        openpanel.setLayout(null);

        welcomeMessage = new JLabel("Hello there! Welcome back. Choose an option below:");
        welcomeMessage.setVerticalTextPosition(SwingConstants.TOP);
        welcomeMessage.setHorizontalTextPosition(SwingConstants.CENTER);
        welcomeMessage.setBounds(50, 20, 500, 200);
        welcomeMessage.setFont(new Font("Arial", Font.PLAIN, 17));

        openpanel.setBounds(0, 0, 500, 500);
        openpanel.add(welcomeMessage);

        loadButton.setBounds(200, 170, 100, 50);
        loadButton.setFont(new Font("Arial", Font.CENTER_BASELINE, 15));
        loadButton.setText("Load Data");
        loadButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                LoadCompletePanel loadCompletePanel = new LoadCompletePanel();
                openpanel.removeAll();
                openpanel.add(loadCompletePanel);
                System.out.println("ADDED");
                openpanel.revalidate();
                openpanel.repaint();
            }
        });
        loadButton.setFocusable(false);

        resetButton.setBounds(200, 230, 100, 50);
        resetButton.setFont(new Font("Arial", Font.CENTER_BASELINE, 15));
        resetButton.setText("Reset Data");
        resetButton.addActionListener(this);
        resetButton.setFocusable(false);

        openpanel.add(loadButton);
        openpanel.add(resetButton);
    }

    public void actionPerformed(ActionEvent event) {
        
    }

    public static void main(final String[] args) {
        EventQueue.invokeLater(() -> new OpenFrame());
    }
}

class LoadCompletePanel extends JPanel {
    private JPanel loadCompletePanel;
    private JLabel loadCompleteMessage;

    public LoadCompletePanel() {
        super(null);
        setBounds(0, 0, 300, 300);
        loadCompletePanel = new JPanel();
        loadScreenPanel();
        loadCompletePanel.add(loadCompleteMessage);
        loadCompletePanel.setBounds(200, 170, 100, 50);
        add(loadCompletePanel);
        setVisible(true);
    }

    private void loadScreenPanel() {
        loadCompletePanel.setLayout(null);
        loadCompleteMessage = new JLabel("Loading Complete.");
        loadCompleteMessage.setBounds(1, 1, 50, 20);
        loadCompletePanel.add(loadCompleteMessage);
    }
}

最初的Swing示例代碼（來自上個世紀，大約 1998 年）總是將應用程式類擴展為JFrame或JPanel. 這不是必需的。

用戶單擊后，您似乎要替換openpanel為。由于您沒有使用通過單擊 JButton 獲取 JPanel

這是單擊后應用程式的螢屏截圖loadButton。

通過單擊 JButton 獲取 JPanel

您最好使用適當的通過單擊 JButton 獲取 JPanel

點擊后loadButton

通過單擊 JButton 獲取 JPanel

請注意，我使用了以下 SO 問題的答案中的代碼，以便顯示loadCompleteMessage在其父容器的中心。

在 JPanel 上將 JLabel 居中

uj5u.com熱心網友回復：

請執行下列操作：

 public void actionPerformed(ActionEvent e) {
     LoadCompletePanel loadCompletePanel = new LoadCompletePanel();
     openpanel.add(loadCompletePanel);
     openPanel.repaint();
     openPanel.revalidate();
 }

此代碼將確保面板繪制新添加的組件。

uj5u.com熱心網友回復：

由于我不熟悉與 setBounds(...) 關聯的 setLayout(null) 并且很長時間沒有使用 Swing，因此我從未設法直接顯示 LoadCompletePanel 實體。無論如何，問題出在動作監聽器中，我用 LoadindCompleteLabel 標簽替換了 loadCompletePanel 面板。要使此標簽出現在動作偵聽器中，您必須在受影響的容器上呼叫 repaint()。

    public void openPanel() {
    openpanel.setLayout(null);

    welcomeMessage = new JLabel("Hello there! Welcome back. Choose an option below:");
    welcomeMessage.setVerticalTextPosition(SwingConstants.TOP);
    welcomeMessage.setHorizontalTextPosition(SwingConstants.CENTER);
    welcomeMessage.setBounds(50, 20, 500, 200);
    welcomeMessage.setFont(new Font("Arial", Font.PLAIN, 17));

    openpanel.setBounds(0, 0, 500, 500);
    openpanel.add(welcomeMessage);
    openpanel.add(loadCompletePanel);
    
    
    JLabel LoadindCompleteLabel = new JLabel("Loading Complete.");
    LoadindCompleteLabel.setBounds(130, 50, 500, 200);

    
    loadButton.setBounds(200, 170, 100, 50);
    loadButton.setFont(new Font("Arial", Font.CENTER_BASELINE, 15));
    loadButton.setText("Load Data");
    loadButton.addActionListener(new ActionListener() {
        
        public void actionPerformed(ActionEvent e) {
            openpanel.add(LoadindCompleteLabel);
            openpanel.repaint();
        }
        
    });
    
    loadButton.setFocusable(false);

    resetButton.setBounds(200, 230, 100, 50);
    resetButton.setFont(new Font("Arial", Font.CENTER_BASELINE, 15));
    resetButton.setText("Reset Data");
    resetButton.addActionListener(this);
    resetButton.setFocusable(false);

    openpanel.add(loadButton);
    openpanel.add(resetButton);
}

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