Unable to run java program using command prompt

Question

How I can run java program using command prompt? I already run my program using command prompt but i get this error Could not find or load main class ReadWriteTextFile

Answer 1

Well, there are a few conditions on running a java class:

• First of all, the file you want to run should have a public class, with the same name as the file. For instance, Test.java would contain the Test class.

• The public class should have a main method. This is a static method. It's arguments are the command line arguments passed. It's signature must be public static void main(String[] args) .

As an example class you can call from the command line:

public class ReadWriteTextFile {
    public static void main(String[] args) {
        readWriteTextFile();
    }
    public static void readWriteTextFile() {
        // Do stuff.
    }
}

If saved in the file ReadWriteTextFile.java , you can compile and call it like this:

$ javac ReadWriteTextFile.java
$ java ReadWriteTextFile
$

Seen from the error message you get, your file is probably called ReadWriteTextFile , but you haven't got a public ReadWriteTextFile class with a main method in it.

Answer 2

Check your entry point specification in your manifest as explained here : You should set an entry like this one: Main-Class: YourPackage.ReadWriteTextFile Maybe the package path is missing? I got myself this kind of issue when launching jar files... I hope this helps.