Question

我尝试将此组件添加到框架中，但它遇到了同样的问题。所以我创建了一个类和一个面板，我正在尝试这种方式。但现在我有同样的问题。我的按钮都没有出现在框架内。我也得到了一个非法的例子。（此代码现在有效）我改变了如下所示。

import java.awt.*;
import javax.swing.*;
public class Pan extends JFrame {
 public Pan(){
    setLayout(new GridLayout(1,1));
     JPanel panel1 = new JPanel(new GridLayout(4,3));

    JButton zero = new JButton(""+0);
    JButton one = new JButton(""+1);
    JButton two = new JButton(""+2);
    JButton three = new JButton(""+3);
    JButton four = new JButton(""+4);
    JButton five = new JButton(""+5);
    JButton six = new JButton(""+6);
    JButton seven = new JButton(""+7);
    JButton eight = new JButton(""+8);
    JButton nine = new JButton(""+9);
panel1.add(zero);
panel1.add(one);
panel1.add(two);
panel1.add(three);
panel1.add(four);
panel1.add(five);
panel1.add(six);
panel1.add(seven);
panel1.add(eight);
panel1.add(nine);

add(panel1);
}

public static void main(String[] args){
    Pan frame = new Pan();
    frame.setSize(800, 800);
    frame.setLocationRelativeTo(null);
    frame.setTitle("Number Pad");
    frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
    frame.setVisible(true);

}}

Answer 1

以下行的例外情况 - 将容器的父级添加到自身

panel.add(panel);

另外一项更改总是从EventQueue.invokeLater()

调用它

public static void main(String[] args) {

    EventQueue.invokeLater(new Runnable() {

        @Override
        public void run() {
            Pan frame = new Pan();
            ...
            frame.setVisible(true);

        }
    });

}

Answer 2

正如ZouZou指出的那样，void Pan（）不是构造函数，因此不会被调用。您还可以将面板添加到框架的rootPane。

试试这段代码：

import java.awt.*;
import javax.swing.*;
public class Pan extends JFrame {
public Pan(){
    JPanel panel = new JPanel(new GridLayout(4,3));

    JButton zero = new JButton(""+0);
    JButton one = new JButton(""+1);
    JButton two = new JButton(""+2);
    JButton three = new JButton(""+3);
    JButton four = new JButton(""+4);
    JButton five = new JButton(""+5);
    JButton six = new JButton(""+6);
    JButton seven = new JButton(""+7);
    JButton eight = new JButton(""+8);
    JButton nine = new JButton(""+9);

    panel.add(zero);
    panel.add(one);
    panel.add(two);
    panel.add(three);
    panel.add(four);
    panel.add(five);
    panel.add(six);
    panel.add(seven);
    panel.add(eight);
    panel.add(nine);
    add(panel);
}

public static void main(String[] args){
    Pan frame = new Pan();
    frame.setSize(800, 800);
    frame.setLocationRelativeTo(null);
    frame.setTitle("Number Pad");
    frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
    frame.setVisible(true);

}}

为什么我的框架内不会出现任何内容？

2 个答案: