Jpanels为什么不起作用？

Question

I am trying to write a program with JPanels and for the life of me, I can't seem to get the JPanels to go into the proper positions. I don't have a clue what I am doing wrong.

Here is some of the code I have so far:

package mainGUIWindowFrames;

import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;

import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class CustomerWindow extends JFrame
{
//Attribute
private JTextField      textTF;
private JButton         copyButton;
private JLabel          copyLabel;
private Border          panelEdge;

//Constructor
public CustomerWindow()
{
    this.setBounds(100,100,800,600);
    panelEdge = BorderFactory.createEtchedBorder();

    JPanel mainPanel = new JPanel(new BorderLayout(5, 5));
    mainPanel.add(createCustomerPanel(), BorderLayout.NORTH);
    mainPanel.add(createCustomerInfoPanel(), BorderLayout.EAST);
    mainPanel.add(createSearchPanel(), BorderLayout.WEST);
}

//Operational Methods
public JPanel createCustomerPanel()
{
    JPanel customerPanel = new JPanel();

    JLabel customerL = new JLabel("Clients",SwingConstants.CENTER);
    customerL.setForeground(Color.blue);
    customerL.setFont(new Font("Copperplate Gothic Bold",Font.BOLD,48));
    customerPanel.add(customerL);


    customerPanel.setBorder(panelEdge);

    return customerPanel;
}

public JPanel createCustomerInfoPanel()
{
    JPanel infoPanel = new JPanel();
    infoPanel.setBorder(panelEdge);

    JLabel infoL = new JLabel("Clients",SwingConstants.CENTER);
    infoL.setForeground(Color.blue);
    infoL.setFont(new Font("Copperplate Gothic Bold",Font.BOLD,48));
    infoPanel.add(infoL);


    //add a text field
    textTF = new JTextField(50);
    infoPanel.add(textTF);

    //add a button
    copyButton = new JButton("Copy Text");
    copyButton.addActionListener(new ButtonListener());
    infoPanel.add(copyButton);

    copyLabel = new JLabel("-----------------");

    infoPanel.add(copyLabel);


    return infoPanel;
}

public JPanel createSearchPanel()
{
    JPanel lowerPanel = new JPanel();
    JLabel label = new JLabel("Text Transferred from JList:");

    //the spot where the data shows up

    lowerPanel.add(label);
    return lowerPanel;
}

The only Panel that shows up is the CreateCustomerPanel(). I have no idea what I need to do to get the other two panels to work.

If you could help me out that would be great!!

---

well I eventually wound up solving it by creating another panel and moving the panels I had out of the main constructor.

public CustomerWindow() {

    panelEdge = BorderFactory.createEtchedBorder();




}
public  JPanel createNorthPanel()
{
    JPanel customerPanel = new JPanel();
    JLabel customerL = new JLabel("Clients",SwingConstants.CENTER);
    customerL.setForeground(Color.blue);
    customerL.setFont(new Font("Copperplate Gothic Bold",Font.BOLD,48));
    customerPanel.add(customerL);


    customerPanel.setBorder(panelEdge);

    return customerPanel;

}   
//Operational Methods
public JPanel createCustomerPanel()
{
    JPanel mainPanel = new JPanel(new BorderLayout(5, 5));
    mainPanel.add(createNorthPanel(), BorderLayout.NORTH);
    mainPanel.add(createCustomerInfoPanel(), BorderLayout.EAST);
    mainPanel.add(createSearchPanel(), BorderLayout.WEST);

    return mainPanel;


}


public JPanel createCustomerInfoPanel()
{
    JPanel infoPanel = new JPanel();
    Box vBox = Box.createVerticalBox();
    infoPanel.setBorder(panelEdge);


    JLabel infoL = new JLabel("Clients",SwingConstants.CENTER);
    infoL.setForeground(Color.blue);
    infoL.setFont(new Font("Copperplate Gothic Bold",Font.BOLD,48));
    infoPanel.add(infoL);


    //add a text field
    clientId = new JTextField(10);
    vBox.add(clientId);
    vBox.add(Box.createVerticalStrut(25));
    fName = new JTextField(10);
    vBox.add(fName);
    vBox.add(Box.createVerticalStrut(25));
    lName = new JTextField(10);
    vBox.add(lName);
    vBox.add(Box.createVerticalStrut(25));
    address = new JTextField(10);
    vBox.add(address);
    vBox.add(Box.createVerticalStrut(25));
    postalCode = new JTextField(10);
    vBox.add(postalCode);
    vBox.add(Box.createVerticalStrut(25));
    number = new JTextField(10);
    vBox.add(number);
    vBox.add(Box.createVerticalStrut(25));
    type = new JTextField(10);
    vBox.add(type);


    infoPanel.add(vBox);


    return infoPanel;

Ive still got a lot of work to do but thanks to all those who helped me out!!

Answer 1

Based on your example, nothing should show up, as you've not added mainPanel to anything.

Once I did that, I was able to get

to show up...

Modified code example

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.Border;

public class CustomerWindow extends JFrame {
//Attribute

    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) {
                }

                CustomerWindow frame = new CustomerWindow();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    private JTextField textTF;
    private JButton copyButton;
    private JLabel copyLabel;
    private Border panelEdge;

//Constructor
    public CustomerWindow() {
        this.setBounds(100, 100, 800, 600);
        panelEdge = BorderFactory.createEtchedBorder();

        JPanel mainPanel = new JPanel(new BorderLayout(5, 5));
        mainPanel.add(createCustomerPanel(), BorderLayout.NORTH);
        mainPanel.add(createCustomerInfoPanel(), BorderLayout.EAST);
        mainPanel.add(createSearchPanel(), BorderLayout.WEST);

        add(mainPanel);
    }

//Operational Methods
    public JPanel createCustomerPanel() {
        JPanel customerPanel = new JPanel();

        JLabel customerL = new JLabel("Clients", SwingConstants.CENTER);
        customerL.setForeground(Color.blue);
        customerL.setFont(new Font("Copperplate Gothic Bold", Font.BOLD, 48));
        customerPanel.add(customerL);

        customerPanel.setBorder(panelEdge);

        return customerPanel;
    }

    public JPanel createCustomerInfoPanel() {
        JPanel infoPanel = new JPanel();
        infoPanel.setBorder(panelEdge);

        JLabel infoL = new JLabel("Clients", SwingConstants.CENTER);
        infoL.setForeground(Color.blue);
        infoL.setFont(new Font("Copperplate Gothic Bold", Font.BOLD, 48));
        infoPanel.add(infoL);

        //add a text field
        textTF = new JTextField(50);
        infoPanel.add(textTF);

        //add a button
        copyButton = new JButton("Copy Text");
//        copyButton.addActionListener(new ButtonListener());
        infoPanel.add(copyButton);

        copyLabel = new JLabel("-----------------");

        infoPanel.add(copyLabel);

        return infoPanel;
    }

    public JPanel createSearchPanel() {
        JPanel lowerPanel = new JPanel();
        JLabel label = new JLabel("Text Transferred from JList:");

        //the spot where the data shows up
        lowerPanel.add(label);
        return lowerPanel;

    }

}

Answer 2

您没有在构造函数中添加主面板。

add(mainPanel);