为什么我的 java 程序在没有 eclipse 中的 main(String[] args) 方法的情况下运行？

Question

import java.awt.Color;
import acm.graphics.*;
import acm.program.*;

public class ColHelloWorld extends GraphicsProgram {
    public void run() {
        GLabel label = new GLabel("Hello World", 200, 75);
        label.setFont("SansSerif-96");
        label.setColor(Color.RED);
        add(label);

        println("Hello dumbass");
    }
}

So I have this sample code which I can run in eclipse by going to Run As option for the project and selecting run as " Java Application ". My question is why does this compile and run even though it doesn't have a main() method call. My guess is this works because of the acm library I imported and extending the GraphicsProgram class that already has a main() method but I am still a little confused as to why it works and any clarification would be helpful. Also, if I wanted to add a main() method to the above code and still keep the run() method within it, how would I go about implementing it? I can give more details if you need any, thank you for answering.

Answer 1

GraphicsProgram extends Program which contains the following documentation;

In many programming environments, objects that are specific instances of a Program subclass will run automatically without any special action on your part. For maximum portability, you might want to define a static main method as described in the comments for the standard implementation of main.