Java GUI 显示空白

Question

所以我试图在 Java 中创建我的第一个 GUI，但它是空白的。据我所知，我所做的一切都是正确的，但当然因为它只是空白，所以我显然做错了什么。我有一个 mainclass 和一个 class 用于 JFrame 及其所有内容。我没有收到任何错误，除了 public class MainFrame 给我 "The serializable class MainFrame does not declare a static final serialVersionUID field of type long".

package main;

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

import gui.MainFrame;

public class Main {

public static void main(String[] args) {

     SwingUtilities.invokeLater(new Runnable() {

         public void run() 
             MainFrame frame = new MainFrame();

             frame.setTitle("GUI");

             frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

             frame.setSize(800, 400);

             frame.setVisible(true);

        }
     });
 }

}

.

package gui;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class MainFrame extends JFrame {

 private JButton button;
 private Container cont;

 public MainFrame(){
     Container cont = new Container();

     setLayout(new BorderLayout());

     JPanel panel = new JPanel();
     panel.setLayout(new BorderLayout());

     JButton button = new JButton("Change Color");

     panel.add(button, BorderLayout.CENTER);

     cont.add(panel, BorderLayout.CENTER);

     cont.setBackground(Color.GREEN);

     button.addActionListener(new ActionListener() {

         public void actionPerformed(ActionEvent e) {
             cont.setBackground(Color.CYAN);

         }
     });

 }
}

Answer 1

您没有将 Container cont 添加到框架中。

Answer 2

忘记将组件添加到框架：

panel.add(cont);

Java GUI 显示空白

Java GUI shows up blank

java

user-interface

swing

jpanel

jframe