How to Fix The IllegalStateException in Java
An IllegalStateException is a runtime exception in Java that is thrown to indicate that a method has been invoked at an illegal or inappropriate time. To use an analogy, invoking a method in Java when the system is not in the appropriate state is like trying to start a car while it is in "Drive". Just as the car will not start because it is unsafe, a method call results in an IllegalStateException when the internal conditions necessary for its execution are not met.