Java图形无法执行绘画功能而无需扩展 [英] Java Graphics Not Executing Paint Function Without extends

问题描述

我一直在与Java的图形系统作斗争(或很多)，我一直在研究用于绘制Java图形的文档和教程.

I've been battling a bit (or a lot) with Java's Graphics, I've been going through the documentation and tutorials for drawing Java Graphics.

我发现的每个示例似乎都有一个主类，该主类扩展了JPanel，然后调用自身以某种方式执行paint函数.

Every example I've found seems to have a main class that extends a JPanel and then calls itself which executes the paint function somehow.

是否可以完全不使用扩展来绘制图形?我有一个基本程序

Is it possible to draw graphics without using extends at all? I have a basic program

import javax.swing.*;
import awt.Graphics;

public class basicWindow {

    public static void main(String[] args) {

        JFrame frame = new JFrame();
        frame.setTitle("Basic Window");
        frame.setSize(300, 300);
        frame.setDefaultCloseOperation(JInternalFrame.DISPOSE_ON_CLOSE);

        JPanel panel = new JPanel();

        frame.add(panel);

        frame.setVisible(true);

    }

    public void paint(Graphics g) {

        g.fillRect(5, 15, 50, 75);

    }

}

这将打开一个窗口，但不会绘制任何我期望的东西，因为我不知道如何执行绘画功能.

This opens a window but doesn't draw anything which I was I expect because I don't know how to execute the paint function.

如果我尝试

Graphics graphic = new Graphics();

paint(graphic);

这是行不通的，因为它抱怨类是抽象的.

It doesn't work because it's complaining about the class being abstract.

推荐答案

是否可以完全不使用扩展来绘制图形?

Is it possible to draw graphics without using extends at all?

是的，肯定有可能.正如@HovercraftFullOfEels在评论中提到的:

Yes, it sure is possible. As mentioned by @HovercraftFullOfEels in a comment:

您可以在 BufferedImage 上绘制..

如果您在 JLabel 中显示该图像(将其称为 label )，则要在图像更改后更新屏幕，只需调用:

If you display that image in a JLabel (lets call it label) then to get the screen to update after the image has changed, simply call:

label.repaint();

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