Java Swing-未将Jpanel添加到JFrame中

Question

我一直在使用JFrame进行我的项目，但遇到了一个问题。这是我的代码：

public class WritePatient extends JFrame{
    JFrame frame = new JFrame();  
    
    JPanel panel1 = new JPanel();
    JPanel panel2 = new JPanel();
    JPanel panel3 = new JPanel();
    JPanel panel4 = new JPanel();
    
    private JTextField field1;
    private JTextField field2;
    private JTextField field3;
    private JTextArea field4;
    
    private final JLabel fNameLabel = new JLabel("First name: ");
    private final JLabel lNameLabel = new JLabel("Last name: ");
    private final JLabel ohipLabel = new JLabel("OHIP number: ");
    private final JLabel symptomLabel = new JLabel("Symptoms: ");
    
    private final JButton submitButton = new JButton("Register");
    private final JButton readButton = new JButton("Display List");
    
    String fName = "";
    String lName = "";
    String ohip = "";
    String symptom = "";
    ArrayList<Patient> sympList = new ArrayList<>();
    String date = "";
    
    public void patientFrame() throws NumberFormatException{

        setLayout(new GridLayout(6,1));
        
        try {
            panel1.setLayout(null);
            panel2.setLayout(null);
            panel3.setLayout(null);
            panel4.setLayout(null);
            
            field1 = new JTextField(10);
            panel1.add(fNameLabel);
            panel1.add(field1);
//          add(fNameLabel);
//          add(field1);
            
            field2 = new JTextField(10);
            panel2.add(lNameLabel);
            panel2.add(field2);
//          add(lNameLabel);
//          add(field2);
            
            field3 = new JTextField(10);
            panel3.add(ohipLabel);
            panel3.add(field3);
//          add(ohipLabel);
//          add(field3);
            
            field4 = new JTextArea(5, 10);
            panel4.add(symptomLabel);
            panel4.add(field4);
//          add(symptomLabel);
//          add(field4);
            
            frame.add(panel1);
            frame.add(panel2);
            frame.add(panel3);
            frame.add(panel4);  
            
            add(submitButton);
            add(readButton);
            
            ButtonHandler btHandler = new ButtonHandler();
            submitButton.addActionListener(btHandler);
            readButton.addActionListener(btHandler);

还有，这是我的主要。java：

    public class Main {
    public static void main(String[] args) {
        WritePatient writePatient = new WritePatient();
        writePatient.setSize(300,300);
        writePatient.setTitle("Information");
        writePatient.patientFrame();
        writePatient.setVisible(true);
        writePatient.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

我想做的是向面板添加文本字段和标签。但是，当我运行此代码时，它会显示：结果

如果我在框架中添加标签和文本字段，效果很好。你能帮我解决这个问题吗？非常感谢你。

Answer 1

您需要将按钮添加到您选择的面板中，我假设您想要将它们添加到面板4

panel4.add(submitButton);
panel4.add(readButton);

如果你想把它们添加到框架中，你可以只添加那些

frame.add(submitButton);
frame.add(readButton);