I have below classes.
public class ValidationException extends RuntimeException {
}
and
public class ValidationException
One case where it is common practice to throw a RuntimeException is when the user calls a method incorrectly. For example, a method can check if one of its arguments is incorrectly null. If an argument is null, the method might throw a NullPointerException, which is an unchecked exception.
Generally speaking, do not throw a RuntimeException or create a subclass of RuntimeException simply because you don't want to be bothered with specifying the exceptions your methods can throw.
Here's the bottom line guideline: If a client can reasonably be expected to recover from an exception, make it a checked exception. If a client cannot do anything to recover from the exception, make it an unchecked exception.
for more read this.