如何在Applet 扩展类中调用paint 方法? [英] How to call a paint method inside Applet extended class?

问题描述

我有 2 个名为 PaintMe.java 和 Starter.java 的类文件.PaintMe.java 包含:

import java.applet.Applet;导入 java.awt.*;公共类 PaintMe 扩展 Applet {公共无效油漆(图形g){g.setColor(Color.red);g.drawString("你好", 15, 25);}}

Starter.java 包含:

import java.applet.Applet;导入 java.awt.Graphics;公共类初学者{公共静态无效主(字符串 [] args){PaintMe ring = new PaintMe();环.paint();}}

那么问题是，如何通过从 Starter.java 调用绘制方法来绘制字符串?

解决方案

要编译，请更改

ring.paint();

...到...

ring.repaint();

<小时>

注意事项

1. 在这个千禧年不要使用 AWT 进行编码.使用 Swing(它提供了一个 JApplet).
2. 不要从 main(String[]) 启动小程序.小程序在嵌入网页时由 JRE 启动(或使用 JWS 启动).可以在面板中设计 GUI，然后将其放入自由浮动的应用程序或小程序中.这被称为混合动力车.但是框架和小程序都分别添加了 GUI，这(通常)是不同的类.
3. 现有的主要是无用的.除非将小程序添加到容器中并使其可见，否则代码会成功运行，但会在片刻结束时不显示任何内容.

<小时>

更新 1

<块引用>

..试过了，但它仍然没有在小程序窗口中绘制我的字符串.

试试这个.

来源

//导入 java.applet.Applet;导入 java.awt.*;公共类 PaintMe 扩展 Applet {公共无效油漆(图形g){g.setColor(Color.red);g.drawString("你好", 15, 25);}}

提示

>javac PaintMe.java>小程序查看器 PaintMe.java

截图

<小时>

更新 2

<块引用>

..我需要从 Starter.java 类启动它.

我认为这是一个愚蠢的要求，似乎 JWS(如在评论中提到和链接)启动 JFrame 是查看此 GUI 的最佳方式.OTOH，这是 Starter 类的(非常)幼稚的实现，它将在屏幕上显示该小程序.

它混合了 AWT 和 Swing(不好)，它不尝试实现任何类型的小程序上下文，也不调用小程序 init/start/stop/destroy 方法，但足以从另一个类在屏幕上获取小程序.

import java.awt.Dimension;导入 javax.swing.JOptionPane;公共类初学者{公共静态无效主(字符串 [] args){PaintMe ring = new PaintMe();ring.setPreferredSize(new Dimension(250,30));JOptionPane.showMessageDialog(null, ring);}}

I have 2 class files called PaintMe.java and Starter.java. PaintMe.java contains:

import java.applet.Applet;
import java.awt.*;

public class PaintMe extends Applet {
    public void paint(Graphics g) {
        g.setColor(Color.red);
        g.drawString("HELLOOO", 15, 25);
    }
}

Starter.java contains:

import java.applet.Applet;
import java.awt.Graphics;


public class Starter {
    public static void main(String[] args) {
        PaintMe ring = new PaintMe();
        ring.paint();
    }
}

So question is, how can I paint my string with calling a paint method from Starter.java?

解决方案

To get it to compile, change

ring.paint();

..to..

ring.repaint();

---

Notes

1. Don't code using AWT in this millennium. Use Swing (which offers a JApplet).
2. Don't start an applet from the main(String[]). An applet is started by the JRE when it is embedded in a web page (or launched using JWS). A GUI can be designed in a panel, that is then put in a free-floating application or applet. That is known as a hybrid. But both frame and applet separately add the GUI, which is (most often) a different class to either.
3. The main as it exists is useless. Unless the applet is added to a container and made visible, the code will run successfully but end in a few moments without displaying anything.

---

Update 1

..tried that, but it still doesn't draw my string in the applet window.

Try this.

Source

// <applet code='PaintMe' width=300 height=50></applet>
import java.applet.Applet;
import java.awt.*;

public class PaintMe extends Applet {
    public void paint(Graphics g) {
        g.setColor(Color.red);
        g.drawString("HELLOOO", 15, 25);
    }
}

Prompt

> javac PaintMe.java
> appletviewer PaintMe.java

Screenshot

---

Update 2

..I need to have it started from Starter.java class.

I think that is a silly requirement, and it seems like JWS (as mentioned & linked in comments) launching a JFrame is the best way to view this GUI. OTOH, here is a (very) naive implementation of the Starter class that will show that applet on-screen.

It mixes AWT and Swing (bad), it does not attempt to implement any sort of applet context, and does not call the applet init/start/stop/destroy methods, but is enough to get the applet on-screen from another class.

import java.awt.Dimension;
import javax.swing.JOptionPane;

public class Starter {
    public static void main(String[] args) {
        PaintMe ring = new PaintMe();
        ring.setPreferredSize(new Dimension(250,30));
        JOptionPane.showMessageDialog(null, ring);
    }
}

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