"Could not find or load main class" when running the program

I had a case where even the command

java -classpath . HelloWorld

Gave the error "Could not find or load main class" solved this way

java -classpath "jar_name" com.list_of_your_packages.launcher

That is, you had to specify the jar itself in classpath, and then specify the full path to the class with the main method

For a class in the src directory and in the basic package,

package basic;

public class Main {

    public static void main(String[] args) {
          System.out.println("Hello from Main");

    }

}

It works like this for me

$ javac src/basic/Main.java
$ java -cp src basic.Main
Hello from Main

Maybe someone will need it. I found another answer that helped me:

Sometimes it is useful to read not only books, but also documentation. http://docs.oracle.com/javase/7/docs/technotes/tools/windows/java.html

The Java command does not perceive your e:\MyJava\example as a path in general.

She thinks it's a class name. The paths are set differently. This is a large and complex topic-classpath.

java -cp e:\MyJava\ example

We specify to search for classes in e:\MyJava\ to run the class example.

Herbert Schildt in his little book on JDK8 gives a simple but A very useful example of compiling and running a program:

EXAMPLE:

The contents of the Book file.java

package bookpack;

class Book {
    //....
}

This file must be placed in the bookpack

Compile it like this:

javac bookpack/Book.java

And run like this:

java bookpack.Book

* * * ATTENTION ***
Do not forget that for the normal execution of the above commands, the current directory must be a directory that is parent to the bookpack directory.

P.S. I personally checked it-it works! Go ahead! May the force come with you! ;)

I spent a lot of time to solve this issue, and the solution is as follows. You need to correctly register the environment variables. You need to specify the path to bin and the path to lib in the environment variables. Very few people talk about lib. If you run from the command line and the path to the libraries is not specified in the environment variables, the jvm does not know where to get them. Win 10. For example c:\Program Files\Java\jdk-10.0.1\lib\ and c:\Program Files\Java\jdk-10.0.1\bin\
Good luck!

In the environment variables where you write the path to the JDK to the CLASSPATH variable, put".; "before the path. I got .;C:\Program Files\Java\jdk1.8.0_201\bin The dot indicates the current directory. After editing, don't forget to restart Windows.

The problem is solved if you change the start line

Instead of the javac command C:\Java\HelloWorld.java run like this javac C:\Java\HelloWorld

With the removal of the file extension *.the java main class is detected. The program starts. Why exactly, I did not understand.

• Navigate to the desired folder using the console command cd;
• You can also add the desired path to the environment variable CLASSPATH;
• The easiest way is to call CMD from TotalCommander, going to the desired cathalo.