public class checkGpa extends JFrame implements ActionListener { static JButton backButton = new JButton("back"); JFrame frame = new JFrame("GPA"); Label averageGPALabel = new Label("average GPA"); JTextField averageGPAField = new JTextField(); Label weightedGPALabel = new Label("weighted GPA"); JTextField weightedGPAField = new JTextField(); /** * Constructor creates a JFrame and sets its properties. * Calls the PersonalReader method to read and display student GPA information. * Adds a JPanel to the JFrame and creates and positions various GUI elements. * Sets an ActionListener for the back button to return to the previous window. * * @throws IOException if an error occurs while reading from the JSON file */ public checkGpa() throws IOException { frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); frame.setSize(400, 300); // Create and set properties for JPanel JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS)); panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); // Create and position GUI elements averageGPALabel.setBounds(10, 10, 20, 10); averageGPALabel.setBounds(20, 10, 100, 10); averageGPAField.setBounds(120, 10, 100, 10); weightedGPALabel.setBounds(10, 40, 100, 10); weightedGPAField.setBounds(120, 40, 100, 10); backButton.setAlignmentX(Component.CENTER_ALIGNMENT); // Display GPA information by calling PersonalReader method GPA gpa = PersonalReader(); averageGPAField.setText(gpa.getAverageGPA()); weightedGPAField.setText(gpa.getWeightedGPA()); panel.add(averageGPALabel); panel.add(averageGPAField); panel.add(weightedGPALabel); panel.add(weightedGPAField); panel.add(backButton); backButton.addActionListener(this); frame.add(panel); frame.setVisible(true); }使用tdd改写

首先，我们需要确定该类的功能和输入输出：

- 功能：显示学生的平均绩点和加权绩点，并提供返回上一窗口的按钮。
- 输入：无。
- 输出：学生的平均绩点和加权绩点，以及返回上一窗口的按钮。

接下来，我们可以使用 TDD 的思路来分步完成该类的改写：

1. 编写测试用例，测试 checkGpa 类的构造函数是否能够正确创建 JFrame 和显示学生绩点信息。

@Test
public void testConstructor() throws IOException {
    checkGpa gpa = new checkGpa();
    JFrame frame = gpa.getFrame();

    assertTrue(frame.isVisible()); // JFrame should be visible
    assertEquals("GPA", frame.getTitle()); // JFrame title should be "GPA"

    // Check if average GPA and weighted GPA fields are displayed correctly
    JTextField averageGPAField = gpa.getAverageGPAField();
    JTextField weightedGPAField = gpa.getWeightedGPAField();
    assertEquals("", averageGPAField.getText()); // Average GPA field should be empty
    assertEquals("", weightedGPAField.getText()); // Weighted GPA field should be empty
}

2. 根据测试用例编写 checkGpa 类的构造函数。

public checkGpa() throws IOException {
    // Create and set properties for JFrame
    JFrame frame = new JFrame("GPA");
    frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    frame.setSize(400, 300);

    // Create and set properties for JPanel
    JPanel panel = new JPanel();
    panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
    panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

    // Create and position GUI elements
    JLabel averageGPALabel = new JLabel("Average GPA");
    JTextField averageGPAField = new JTextField();
    JLabel weightedGPALabel = new JLabel("Weighted GPA");
    JTextField weightedGPAField = new JTextField();
    JButton backButton = new JButton("Back");
    backButton.setAlignmentX(Component.CENTER_ALIGNMENT);

    // Display GPA information by calling PersonalReader method
    GPA gpa = PersonalReader();
    averageGPAField.setText(gpa.getAverageGPA());
    weightedGPAField.setText(gpa.getWeightedGPA());

    // Add GUI elements to JPanel and add ActionListener to back button
    panel.add(averageGPALabel);
    panel.add(averageGPAField);
    panel.add(weightedGPALabel);
    panel.add(weightedGPAField);
    panel.add(backButton);
    backButton.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            frame.dispose(); // Close JFrame when back button is clicked
        }
    });

    // Add JPanel to JFrame and make it visible
    frame.add(panel);
    frame.setVisible(true);

    // Store JFrame and GUI elements for testing
    this.frame = frame;
    this.averageGPAField = averageGPAField;
    this.weightedGPAField = weightedGPAField;
}

3. 编写测试用例，测试 checkGpa 类的 ActionListener 是否能够正确响应返回上一窗口的按钮。

@Test
public void testBackButton() throws IOException {
    checkGpa gpa = new checkGpa();
    JFrame frame = gpa.getFrame();

    JButton backButton = gpa.getBackButton();
    assertTrue(backButton.getActionListeners().length > 0); // ActionListener should be added to back button

    backButton.doClick(); // Simulate clicking back button
    assertFalse(frame.isVisible()); // JFrame should be closed
}

4. 根据测试用例编写 checkGpa 类的 ActionListener。

backButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        frame.dispose(); // Close JFrame when back button is clicked
    }
});

最后，我们需要将 checkGpa 类中的 GUI 元素（例如 JTextField 和 JButton）声明为类的私有成员变量，并提供对应的 getter 方法，以便测试用例可以访问它们。

public class checkGpa extends JFrame implements ActionListener {     
    private JFrame frame;
    private JTextField averageGPAField;
    private JTextField weightedGPAField;
    private JButton backButton;

    public checkGpa() throws IOException {
        // Constructor code
    }

    public JFrame getFrame() {
        return frame;
    }

    public JTextField getAverageGPAField() {
        return averageGPAField;
    }

    public JTextField getWeightedGPAField() {
        return weightedGPAField;
    }

    public JButton getBackButton() {
        return backButton;
    }
}