Why do i see 'noclassdeffounderror' in java?

`NoClassDefFoundError` is an error that arises when a particular class is present at compile-time but was missing at runtime. Example:

// The class was available during compilation but not when running the program.

// Ensure that the class is available in the classpath during runtime.
This error often indicates a misconfigured runtime environment or a missing JAR. Ensure that the classpath is set up correctly.

Beginner's Guide to Java