扩展JPanels的问题 [英] Problems extending JPanels

问题描述

我正在解决一个问题，我在Swing中遇到了一些问题。我在使用扩展JFrame或JComponent的类时没有任何问题，但是当我尝试使用我编写的扩展JPanel的类时，它将不会显示，并且我在该面板上调用的任何内容都不显示，包括添加自定义JComponents到它。创建JPanel扩展类然后将其设置为要在JFrame中使用的内容窗格的一般过程是什么？

Hi I'm working on a problem and I'm having some issues working in Swing. I have no issues working with classes that extend either JFrame or JComponent, but when I try to use a class that I write that extends JPanel, it won't ever show up and nothing that I call on that panel shows up, including adding custom JComponents to it. What is the general procedure for creating a JPanel extendting class and then setting it as the content pane to use in a JFrame?

推荐答案

我（我的个人观点）看不出扩展 JComponent 为 JComponent ， JPanel ， JLabel ，更多继承与组合，例如

I (my personal view) can't see nothing wrong with extends JComponent as JComponent, JPanel, JLabel, more Inheritance versus composition, for example

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

public class CustomComponent extends JFrame {

    private static final long serialVersionUID = 1L;

    public CustomComponent() {
        setTitle("Custom Component Test");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        add(new CustomComponents());
        pack();
        setMinimumSize(getSize());// enforces the minimum size of both frame and component
        setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                CustomComponent main = new CustomComponent();
                //main.display();
            }
        });
    }
}

class CustomComponents extends JComponent {

    private static final long serialVersionUID = 1L;

    @Override
    public Dimension getMinimumSize() {
        return new Dimension(100, 100);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(400, 300);
    }

    @Override
    public void paintComponent(Graphics g) {
        int margin = 10;
        Dimension dim = getSize();
        super.paintComponent(g);
        g.setColor(Color.red);
        g.fillRect(margin, margin, dim.width - margin * 2, dim.height - margin * 2);
    }
}

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