Java can'；I don’我的画框上没有面板。。我做错了什么？

我一直有两个小窗口弹出。我没有看到来自Jpanel类的任何组件。我已经尽我所能。。我知道我做错了什么，但我似乎找不到错误

这是我的Jpanel课程

public class ComponentsPanel  extends JPanel
{        
    // variable declarations       
    // constructor
    public ComponentsPanel()
    {            
        panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        GridBagConstraints gbc = new GridBagConstraints();

        pLabel = new javax.swing.JLabel("Policy #");
        gbc.gridx = 0;
        gbc.gridy = 0;
        panel.add(pLabel, gbc);

        pTextField = new javax.swing.JTextField();
        pTextField.setSize(10, 10);
        gbc.gridx = 1;
        gbc.gridy = 0;
        panel.add(pTextField, gbc);
        this.pNum = pTextField.getText(); 

        newbLabel = new javax.swing.JLabel("NB Date");
        gbc.gridx = 0;
        gbc.gridy = 1;
        panel.add(newbLabel, gbc);

        newbTextField = new javax.swing.JTextField();
        gbc.gridx = 1;
        gbc.gridy = 1;
        panel.add(newbTextField, gbc);

        newbButton = new javax.swing.JButton("NEW DATE");
        gbc.gridx = 2;
        gbc.gridy = 1;
        panel.add(newbButton, gbc);
        this.newbDate = newbTextField.getText(); 

        biLabel = new javax.swing.JLabel("BI Limits");
        gbc.gridx = 0;
        gbc.gridy = 2;
        panel.add(biLabel, gbc);

        biTextField = new javax.swing.JTextField();
        gbc.gridx = 1;
        gbc.gridy = 2;
        panel.add(biTextField, gbc);

        bilimButton = new javax.swing.JComboBox<>(bilimits);
        bilimButton.setToolTipText("Choose Verified BILimits");
        gbc.gridx = 2;
        gbc.gridy = 2;
        panel.add(bilimButton, gbc);

        bicslButton = new javax.swing.JComboBox<>(bicsl);
        gbc.gridx = 3;
        gbc.gridy = 2;
        panel.add(bicslButton, gbc);
        this.biLimit = biTextField.getText();

        lapseLabel = new javax.swing.JLabel("Lapse #");
        gbc.gridx = 0;
        gbc.gridy = 3;
        panel.add(lapseLabel, gbc);

        lapseTextField = new javax.swing.JTextField();
        gbc.gridx = 1;
        gbc.gridy = 3;
        panel.add(lapseTextField, gbc);

        lapseButton = new javax.swing.JComboBox<>(lapse);

        for (int i = 0; i < lapse.length; i++)
        {   
            lapse[i] = Integer.toString(i);

            if (i < 10)
                lapse[i] = "0" + Integer.toString(i);
        }

        lapseButton.setModel(new DefaultComboBoxModel(lapse));
        gbc.gridx = 2;
        gbc.gridy = 3;
        panel.add(lapseButton, gbc);
        this.lapses = lapseTextField.getText();

        noChangeButton = new javax.swing.JButton("NO CHANGE");
        gbc.gridx = 0;
        gbc.gridy = 4;
        panel.add(noChangeButton, gbc);

        changeButton = new javax.swing.JButton("CHANGE");
        gbc.gridx = 1;
        gbc.gridy = 4;
        panel.add(changeButton, gbc);

        decButton = new javax.swing.JButton("DECREASE");
        gbc.gridx = 2;
        gbc.gridy = 4;
        panel.add(decButton, gbc);

        incButton = new javax.swing.JButton("INCREASE");
        gbc.gridx = 3;
        gbc.gridy = 4;
        panel.add(incButton, gbc);  

        cpyButton = new javax.swing.JButton("COPY");
        cpyButton.setToolTipText("copy comment");
        gbc.gridx = 0;
        gbc.gridy = 5;
        panel.add(cpyButton, gbc);

        clrButton = new javax.swing.JButton("CLEAR");
        clrButton.setToolTipText("clear all fields");
        gbc.gridx = 3;
        gbc.gridy = 5;
        panel.add(clrButton, gbc);

        dispTextArea = new javax.swing.JTextArea(10,10);
        dispTextArea.setEditable(true);
        dispTextArea.setLineWrap(true);
        dispTextArea.setColumns(20);
        dispTextArea.setRows(5);
        panel.add(dispTextArea);
        gbc.gridx = 0;
        gbc.gridy = 6;
        gbc.weightx = 0.5;
        gbc.gridwidth = 4;
        gbc.anchor = GridBagConstraints.PAGE_END;
        panel.add(dispTextArea,gbc);

        // adding listeners to components
        // registering all components with their respective listeners
        CompHandler compHandler = new CompHandler();

        pTextField.addActionListener(compHandler);
        biTextField.addActionListener(compHandler);
        newbTextField.addActionListener(compHandler);
        bilimButton.addActionListener(compHandler);
        bicslButton.addActionListener(compHandler);
        noChangeButton.addActionListener(compHandler);
        changeButton.addActionListener(compHandler);
        decButton.addActionListener(compHandler);
        incButton.addActionListener(compHandler);
        decButton.addActionListener(compHandler);
        cpyButton.addActionListener(compHandler);
        clrButton.addActionListener(compHandler);            
    }

    // class to handle text fields
    private class CompHandler implements ActionListener 
    {    
        @Override
        public void actionPerformed(ActionEvent e) {}

    } // end component handler class        
}

---

在

组件spanel

中创建

JPanel

调用

面板

的实例，但决不将其添加到任何内容中

除非您正在做一个更复杂的布局，否则您可以直接将组件添加到

ComponentsPanel

本身

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class MyWindow extends JFrame 
{

    public MyWindow() 
    {
        super("FNA");
        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        ComponentsPanel pane = new ComponentsPanel();
        add(pane);
        setVisible(true);
    }

    public static void main(String[] args) 
    {
        EventQueue.invokeLater(new Runnable() 
        {
            @Override
            public void run() 
            {
                try 
                {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } 
                catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) 
                {
                    ex.printStackTrace();
                }

                new MyWindow();
            }
        });
    }

    public class ComponentsPanel extends JPanel 
    {
        private final JLabel pLabel;
        private final String pNum;
        private final String newbDate;
        private final String biLimit;
        private final String lapses;

        // variable declarations
        // constructor
        public ComponentsPanel() 
        {
            GridBagConstraints gbc = new GridBagConstraints();

            pLabel = new javax.swing.JLabel("Policy #");
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(pLabel, gbc);

            JTextField pTextField = new javax.swing.JTextField();
            pTextField.setSize(10, 10);
            gbc.gridx = 1;
            gbc.gridy = 0;
            add(pTextField, gbc);
            this.pNum = pTextField.getText();

            JLabel newbLabel = new javax.swing.JLabel("NB Date");
            gbc.gridx = 0;
            gbc.gridy = 1;
            add(newbLabel, gbc);

            JTextField newbTextField = new javax.swing.JTextField();
            gbc.gridx = 1;
            gbc.gridy = 1;
            add(newbTextField, gbc);

            JButton newbButton = new javax.swing.JButton("NEW DATE");
            gbc.gridx = 2;
            gbc.gridy = 1;
            add(newbButton, gbc);
            this.newbDate = newbTextField.getText();

            JLabel biLabel = new javax.swing.JLabel("BI Limits");
            gbc.gridx = 0;
            gbc.gridy = 2;
            add(biLabel, gbc);

            JTextField biTextField = new javax.swing.JTextField();
            gbc.gridx = 1;
            gbc.gridy = 2;
            add(biTextField, gbc);

            JComboBox<Object> bilimButton = new javax.swing.JComboBox<>();
            bilimButton.setToolTipText("Choose Verified BILimits");
            gbc.gridx = 2;
            gbc.gridy = 2;
            add(bilimButton, gbc);

            JComboBox<Object> bicslButton = new javax.swing.JComboBox<>();
            gbc.gridx = 3;
            gbc.gridy = 2;
            add(bicslButton, gbc);
            this.biLimit = biTextField.getText();

            JLabel lapseLabel = new javax.swing.JLabel("Lapse #");
            gbc.gridx = 0;
            gbc.gridy = 3;
            add(lapseLabel, gbc);

            JTextField lapseTextField = new javax.swing.JTextField();
            gbc.gridx = 1;
            gbc.gridy = 3;
            add(lapseTextField, gbc);

            JComboBox<Object> lapseButton = new javax.swing.JComboBox<>();

//          for (int i = 0; i < lapse.length; i++) 
//          {
//              lapse[i] = Integer.toString(i);

//              if (i < 10) 
//              {
//                  lapse[i] = "0" + Integer.toString(i);
//              }
//          }

//          lapseButton.setModel(new DefaultComboBoxModel(lapse));
            gbc.gridx = 2;
            gbc.gridy = 3;
            add(lapseButton, gbc);
            this.lapses = lapseTextField.getText();

            JButton noChangeButton = new javax.swing.JButton("NO CHANGE");
            gbc.gridx = 0;
            gbc.gridy = 4;
            add(noChangeButton, gbc);

            JButton changeButton = new javax.swing.JButton("CHANGE");
            gbc.gridx = 1;
            gbc.gridy = 4;
            add(changeButton, gbc);

            JButton decButton = new javax.swing.JButton("DECREASE");
            gbc.gridx = 2;
            gbc.gridy = 4;
            add(decButton, gbc);

            JButton incButton = new javax.swing.JButton("INCREASE");
            gbc.gridx = 3;
            gbc.gridy = 4;
            add(incButton, gbc);

            JButton cpyButton = new javax.swing.JButton("COPY");
            cpyButton.setToolTipText("copy comment");
            gbc.gridx = 0;
            gbc.gridy = 5;
            add(cpyButton, gbc);

            JButton clrButton = new javax.swing.JButton("CLEAR");
            clrButton.setToolTipText("clear all fields");
            gbc.gridx = 3;
            gbc.gridy = 5;
            add(clrButton, gbc);

            JTextArea dispTextArea = new javax.swing.JTextArea(10, 10);
            dispTextArea.setEditable(true);
            dispTextArea.setLineWrap(true);
            dispTextArea.setColumns(20);
            dispTextArea.setRows(5);
            add(dispTextArea);
            gbc.gridx = 0;
            gbc.gridy = 6;
            gbc.weightx = 0.5;
            gbc.gridwidth = 4;
            gbc.anchor = GridBagConstraints.PAGE_END;
            add(dispTextArea, gbc);

            // adding listeners to components
            // registering all components with their respective listeners
            CompHandler compHandler = new CompHandler();

            pTextField.addActionListener(compHandler);
            biTextField.addActionListener(compHandler);
            newbTextField.addActionListener(compHandler);
            bilimButton.addActionListener(compHandler);
            bicslButton.addActionListener(compHandler);
            noChangeButton.addActionListener(compHandler);
            changeButton.addActionListener(compHandler);
            decButton.addActionListener(compHandler);
            incButton.addActionListener(compHandler);
            decButton.addActionListener(compHandler);
            cpyButton.addActionListener(compHandler);
            clrButton.addActionListener(compHandler);
        }

        // class to handle text fields
        private class CompHandler implements ActionListener 
        {
            @Override
            public void actionPerformed(ActionEvent e) {}
        } // end component handler class
    }
}

导入java.awt.EventQueue；
导入java.awt.GridBagConstraints；
导入java.awt.GridBagLayout；
导入java.awt.event.ActionEvent；
导入java.awt.event.ActionListener；
导入javax.swing.DefaultComboxModel；
导入javax.swing.JButton；
导入javax.swing.JComboBox；
导入javax.swing.JFrame；
导入javax.swing.JLabel；
导入javax.swing.JPanel；
导入javax.swing.JTextArea；
导入javax.swing.JTextField；
导入javax.swing.UIManager；
导入javax.swing.UnsupportedLookAndFeelException；
公共类MyWindow扩展了JFrame
{
公共MyWindow（）
{
超级（“FNA”）；
设置大小（300300）；
setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）；
ComponentsPanel窗格=新的ComponentsPanel（）；
添加（窗格）；
setVisible（真）；
}
公共静态void main（字符串[]args）
{
invokeLater（新的Runnable（）
{
@凌驾
公开募捐
{
尝试
{
UIManager.setLookAndFeel（UIManager.getSystemLookAndFeelClassName（））；
} 
catch（ClassNotFoundException |实例化Exception | IllegalacessException |不支持ookandfeelException ex）
{
例如printStackTrace（）；
}
新建MyWindow（）；
}
});
}
公共类组件spanel扩展了JPanel
{
私人终审法院；
私有最终字符串pNum；
私人最终字符串日期；
私有最终字符串biLimit；
私人最终字符串失效；
//变量声明
//建造师
公共组件spanel（）
{
GridBagConstraints gbc=新的GridBagConstraints（）；
pLabel=newjavax.swing.JLabel（“Policy#”）；
gbc.gridx=0；
gbc.gridy=0；
添加（pLabel，gbc）；
JTextField pTextField=newjavax.swing.JTextField（）；
pTextField.setSize（10,10）；
gbc.gridx=1；
gbc.gridy=0；
添加（pTextField，gbc）；
this.pNum=pTextField.getText（）；
JLabel newlabel=newjavax.swing.JLabel（“NB日期”）；
gbc.gridx=0；
gbc.gridy=1；
添加（新标签，gbc）；
JTextField newtextfield=newjavax.swing.JTextField（）；
gbc.gridx=1；
gbc.gridy=1；
添加（新文本字段，gbc）；
jbuttonnewbutton=newjavax.swing.JButton（“新日期”）；
gbc.gridx=2；
gbc.gridy=1；
添加（新按钮，gbc）；
this.newbDate=newtextfield.getText（）；
JLabel biLabel=newjavax.swing.JLabel（“BI限制”）；
gbc.gridx=0；
gbc.gridy=2；
添加（biLabel，gbc）；
JTextField biTextField=newjavax.swing.JTextField（）；
gbc.gridx=1；
gbc.gridy=2；
添加（biTextField，gbc）；
JComboBox-bilimButton=newjavax.swing.JComboBox（）；
设置工具脚本文本（“选择已验证的BILimits”）；
gbc.gridx=2；
gbc.gridy=2；
添加（比林布顿，gbc）；
JComboBox bicslButton=newjavax.swing.JComboBox（）；
gbc.gridx=3；
gbc.gridy=2；
添加（BICSL按钮，gbc）；
this.biLimit=biTextField.getText（）；
JLabel-perseLabel=newjavax.swing.JLabel（“失效#”）；
gbc.gridx=0；
gbc.gridy=3；
添加（标签，gbc）；
JTextField=newjavax.swing.JTextField（）；
gbc.gridx=1；
gbc.gridy=3；
添加（文本字段，gbc）；
JComboBox=newjavax.swing.JComboBox（）；
//for（int i=0；iimport java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class MyWindow extends JFrame 
{

    public MyWindow() 
    {
        super("FNA");
        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        ComponentsPanel pane = new ComponentsPanel();
        add(pane);
        setVisible(true);
    }

    public static void main(String[] args) 
    {
        EventQueue.invokeLater(new Runnable() 
        {
            @Override
            public void run() 
            {
                try 
                {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } 
                catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) 
                {
                    ex.printStackTrace();
                }

                new MyWindow();
            }
        });
    }

    public class ComponentsPanel extends JPanel 
    {
        private final JLabel pLabel;
        private final String pNum;
        private final String newbDate;
        private final String biLimit;
        private final String lapses;

        // variable declarations
        // constructor
        public ComponentsPanel() 
        {
            GridBagConstraints gbc = new GridBagConstraints();

            pLabel = new javax.swing.JLabel("Policy #");
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(pLabel, gbc);

            JTextField pTextField = new javax.swing.JTextField();
            pTextField.setSize(10, 10);
            gbc.gridx = 1;
            gbc.gridy = 0;
            add(pTextField, gbc);
            this.pNum = pTextField.getText();

            JLabel newbLabel = new javax.swing.JLabel("NB Date");
            gbc.gridx = 0;
            gbc.gridy = 1;
            add(newbLabel, gbc);

            JTextField newbTextField = new javax.swing.JTextField();
            gbc.gridx = 1;
            gbc.gridy = 1;
            add(newbTextField, gbc);

            JButton newbButton = new javax.swing.JButton("NEW DATE");
            gbc.gridx = 2;
            gbc.gridy = 1;
            add(newbButton, gbc);
            this.newbDate = newbTextField.getText();

            JLabel biLabel = new javax.swing.JLabel("BI Limits");
            gbc.gridx = 0;
            gbc.gridy = 2;
            add(biLabel, gbc);

            JTextField biTextField = new javax.swing.JTextField();
            gbc.gridx = 1;
            gbc.gridy = 2;
            add(biTextField, gbc);

            JComboBox<Object> bilimButton = new javax.swing.JComboBox<>();
            bilimButton.setToolTipText("Choose Verified BILimits");
            gbc.gridx = 2;
            gbc.gridy = 2;
            add(bilimButton, gbc);

            JComboBox<Object> bicslButton = new javax.swing.JComboBox<>();
            gbc.gridx = 3;
            gbc.gridy = 2;
            add(bicslButton, gbc);
            this.biLimit = biTextField.getText();

            JLabel lapseLabel = new javax.swing.JLabel("Lapse #");
            gbc.gridx = 0;
            gbc.gridy = 3;
            add(lapseLabel, gbc);

            JTextField lapseTextField = new javax.swing.JTextField();
            gbc.gridx = 1;
            gbc.gridy = 3;
            add(lapseTextField, gbc);

            JComboBox<Object> lapseButton = new javax.swing.JComboBox<>();

//          for (int i = 0; i < lapse.length; i++) 
//          {
//              lapse[i] = Integer.toString(i);

//              if (i < 10) 
//              {
//                  lapse[i] = "0" + Integer.toString(i);
//              }
//          }

//          lapseButton.setModel(new DefaultComboBoxModel(lapse));
            gbc.gridx = 2;
            gbc.gridy = 3;
            add(lapseButton, gbc);
            this.lapses = lapseTextField.getText();

            JButton noChangeButton = new javax.swing.JButton("NO CHANGE");
            gbc.gridx = 0;
            gbc.gridy = 4;
            add(noChangeButton, gbc);

            JButton changeButton = new javax.swing.JButton("CHANGE");
            gbc.gridx = 1;
            gbc.gridy = 4;
            add(changeButton, gbc);

            JButton decButton = new javax.swing.JButton("DECREASE");
            gbc.gridx = 2;
            gbc.gridy = 4;
            add(decButton, gbc);

            JButton incButton = new javax.swing.JButton("INCREASE");
            gbc.gridx = 3;
            gbc.gridy = 4;
            add(incButton, gbc);

            JButton cpyButton = new javax.swing.JButton("COPY");
            cpyButton.setToolTipText("copy comment");
            gbc.gridx = 0;
            gbc.gridy = 5;
            add(cpyButton, gbc);

            JButton clrButton = new javax.swing.JButton("CLEAR");
            clrButton.setToolTipText("clear all fields");
            gbc.gridx = 3;
            gbc.gridy = 5;
            add(clrButton, gbc);

            JTextArea dispTextArea = new javax.swing.JTextArea(10, 10);
            dispTextArea.setEditable(true);
            dispTextArea.setLineWrap(true);
            dispTextArea.setColumns(20);
            dispTextArea.setRows(5);
            add(dispTextArea);
            gbc.gridx = 0;
            gbc.gridy = 6;
            gbc.weightx = 0.5;
            gbc.gridwidth = 4;
            gbc.anchor = GridBagConstraints.PAGE_END;
            add(dispTextArea, gbc);

            // adding listeners to components
            // registering all components with their respective listeners
            CompHandler compHandler = new CompHandler();

            pTextField.addActionListener(compHandler);
            biTextField.addActionListener(compHandler);
            newbTextField.addActionListener(compHandler);
            bilimButton.addActionListener(compHandler);
            bicslButton.addActionListener(compHandler);
            noChangeButton.addActionListener(compHandler);
            changeButton.addActionListener(compHandler);
            decButton.addActionListener(compHandler);
            incButton.addActionListener(compHandler);
            decButton.addActionListener(compHandler);
            cpyButton.addActionListener(compHandler);
            clrButton.addActionListener(compHandler);
        }

        // class to handle text fields
        private class CompHandler implements ActionListener 
        {
            @Override
            public void actionPerformed(ActionEvent e) {}
        } // end component handler class
    }
}