Error: Could not find or load main class Test Caused by: java.lang.ClassNotFoundException: Test code example

Example 1: Error: Could not find or load main class -Djava.library.path=.home.hdoop.hadoop-3.3.0.lib.native

Sounds silly, but if you've copied .bashrc lines from somewhere
check that the quotation marks are like this:
    export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib/native"
and not like this
    export HADOOP_OPTS=”-Djava.library.path=$HADOOP_HOME/lib/native”

...took me some time

Example 2: eclipse Error: Could not find or load main class main java.lang.ClassNotFoundException

// Run configurations -> Run -> Run configurations
// In the Classpath tab select "Advanced"
// Add where Eclipse usually put the *.class for the projects, which is (usually) "bin".

Example 3: Error: Could not find or load main class Hello Caused by: java.lang.ClassNotFoundException: Hello studio visual code

package dto;
/**
 * Simple Java program to demonstrate following error
 * Error :Could not find or load main class
 * 
 * @author Javin Paul
 */
public class HelloHP {

    public static void main(String args[]) {
        System.out.println("My first program in Java, HelloWorld !!");
       
    }

}