What is the meaning of “Could not find or load main class”?

“Could not find or load main class” is an error message commonly seen in Java when the Java Virtual Machine (JVM) is unable to find or load the main class of a Java application. This error may occur due to various reasons, including:

1. Incorrect classpath: The classpath is a collection of directories and JAR files that the JVM utilizes to locate classes. If the classpath is not configured correctly, the JVM may not locate the main class of the application. You can configure the classpath using the -cp or -classpath command-line option.

2. Incorrect package name: If the main class is part of a package, you must specify the complete name of the class, including the package name, when launching the application. For example, if the main class is part of the com.example package and is named Main, you should execute the application with the command java com.example.Main.

3. Missing or incorrect main method: The main method serves as the entry point of a Java application and must be declared as public static void main(String[] args). If the main method is absent or has an incorrect signature, the JVM will not be able to launch the application.

4. Incorrect file name: The file name of the main class must match the name of the class, including capitalization. For example, if the main class is named Main, the file should be named Main.java.

To remedy the “Could not find or load main class” error, you should initially verify that the classpath is correctly configured. Additionally, confirm that the package name, class name, and file name are accurate. If the error persists, attempt recompiling the application or launching it with the -verbose:class option to obtain more information about the class loading process.