为什么不显示GUI

Question

这段代码有什么问题？GUI未显示.这是我实验室项目的4x4图片内存的GUI.任何帮助,将不胜感激 .

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class memory extends JFrame implements ActionListener {

    String pictures[]
            = {"riven1.jpg", "riven2.jpg", "riven3.jpg", "riven4.jpg", "riven5.jpg", "riven6.jpg", "riven7.jpg", "riven8.jpg"};

    JButton button[];

    public memory() {
        Container c = getContentPane();
        setTitle("Memory Game");
        panel.setLayout(new GridLayout(4, 4));
        for (int x = 0; x < 16; x++) {
            button[x] = new JButton(new ImageIcon(pictures[x]));
            c.add(button[x]);
            button[x].addActionListener(this);
        }
        setSize(700, 700);
        setVisible(true);
        setLocationRelativeTo(null);
    }

    public void actionPerformed(ActionEvent e) {

    }

    public static void main(String args[]) {
        new memory();
    }
}

Answer 1

有很多问题......

第一:你永远不会初始化 button[]

JButton button[];

public memory() {
    Container c = getContentPane();
    setTitle("Memory Game");
    panel.setLayout(new GridLayout(4, 4));
    for (int x = 0; x < 16; x++) {
        button[x] = new JButton(new ImageIcon(pictures[x]));

这将导致a NullPointerException,button默认为null和尚未初始化

在for循环之前初始化按钮,例如......

button = new JButton[16];

第二:您将所有按钮添加到内容窗格,其默认布局为BorderLayout.这意味着只有您添加的最后一个按钮才会可见,占据整个窗口.

尝试设置内容窗格的布局管理器...

c.setLayout(new GridLayout(4, 4));

第三:panel未定义,所以你的例子甚至不应该编译

 // I have no idea how this is defined...
panel.setLayout(new GridLayout(4, 4));

附注:避免使用尽可能使用的setSize地方pack.这考虑了不同平台如何呈现字体之类的差异.您还应确保在使窗口可见之前设置窗口的状态

    // Use pack instead
    //setSize(700, 700);
    pack();
    setLocationRelativeTo(null);
    setVisible(true);