无法执行小程序（小程序未初始化）

Question

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

/* <applet code="Demonstration_21" width=300 height=300> </applet> */
public class Demonstration_21 extends Applet{

    public void paint(Graphics g){
    g.drawString("Welcome",150,150);
    }
}

I have written this code to run an applet program but whenever I compile it gives some warning as:

1. Demonstration_21.java uses or overrides a deprecated API
2. Recompile with Xlint:deprecation for details.

And whenever I run this code it gives error as:

Demonstration_21 has been compiled by a more recent version of Java
Runtime(class file version 55.0),this version of Java Runtime only 
recognizes class file versions up to 52.0

My appletviewer is not initialized.

Answer 1

You should build it with Java 8 instead of Java 11.

Here is a list of class file versions an the related Java major versions List of Java class file format major version numbers?

Answer 2

you miss something..

In applet tag code attribute you have to specify .class file.

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

/* <applet code="Demonstration_21.class" width=300 height=300> </applet> */
public class Demonstration_21 extends Applet{

    public void paint(Graphics g){
    g.drawString("Welcome",150,150);
    }
}