Why do I get NoSuchMethodError: main in my Applet?

I need help in my Java applet.

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

public class Screen extends Applet{
    public void init(){
        setSize(300,300);
        setBackground(Color.BLACK);
    }
}

This error keeps poppi开发者_如何学编程ng up when I run it.

Exception in thread "main" java.lang.NoSuchMethodError: main

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You are trying to run the applet as an application using

java Screen

That won't work, because an applet is not an application, and doesn't normally have a main() method, which is what java Screen will try to run.

There are a few solutions:

1. Run it using the appletviewer tool, which comes with the JDK.
2. Run it in the browser by embedding it in an HTML page.
3. Make it an "app-applet".

It's been almost ten years since I've actually written an applet so I don't remember the details around #3, but IIRC it involves adding a main() method to the applet and having that main() method launch the applet. I'm sure you can find it on Google.

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Create a new swing form. Since your class extends the default 'applet' you can simply add it to a swing application like this Screen x = new Screen(); then add it to your JFrame YourJframe.add(x); Hope this helped! (I could use an upvote lol :))