How to solve the problem that java cannot find or load the main class

The solution to java's failure to find or load the main class is: 1. Check whether the class name in the code is correct, modify it and recompile and run; 2. Use the command "echo %CLASSPATH%" to check Check whether the path is added to the environment variable, and restart the program after modification; 3. Check the compiler error prompts to check and repair; 4. Confirm that the code path is correct and ensure that the file exists.

Operating system for this tutorial: Windows 10 system, Java 19.0.1 version, Dell G3 computer.

When we run a Java program, we may encounter an exception "The main class cannot be found or cannot be loaded." This is usually due to one of the following reasons:

1. Wrong class name.

2. The path to the class was not added to the CLASSPATH environment variable.

3. Compiler compilation error.

4. The code path is wrong or the file does not exist.

Solution:

1. Check whether the class name in the code is correct. If the class name is wrong, you need to modify it and recompile and run it.

2. Confirm that the path has been added to the CLASSPATH environment variable. You can use the command echo %CLASSPATH% or set CLASSPATH to confirm whether the environment variable is set correctly. If there is no setting or the setting is incorrect, you need to make modifications and re-run the program.

3. If the compiler encounters a compilation error, you need to check the error message and repair it before recompiling and running the program.

4. Confirm that the code path is correct and the file exists. If the path is wrong or the file does not exist, you need to modify the path or complete the file and re-run the program.

At the same time, if none of the above methods solve the problem, you can also try to reinstall the JDK and configure environment variables.

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