What does “Could not find or load main class” mean in java?

If your source code name is HelloWorld.java, your compiled code will be HelloWorld.class.

You will get that error if you call it using:

java HelloWorld.class

Instead, use this:

java HelloWorld

4 years ago

The errors occur when JVM fails to load the main class
The reasons can be:
The class has been declared with the wrong package.
Dependencies missing from the CLASSPATH.
The wrong directory is on the CLASSPATH.
The CLASSPATH of the application is incorrectly specified.

4 years ago

According to the error message ("Could not find or load main class"), there are two categories of problems:

Main class could not be found
Main class could not be loaded (this case is not fully discussed in the accepted answer)
Main class could not be found when there is typo or wrong syntax in the fully qualified class name or it does not exist in the provided classpath.

Main class could not be loaded when the class cannot be initiated, typically the main class extends another class and that class does not exist in the provided classpath.

For example:

public class YourMain extends org.apache.camel.spring.Main

If camel-spring is not included, this error will be reported.

4 years ago