exception - Java equivalent to .NET System.InvalidOperationException

Question

I am not as familiar with Java's exception packages as with those of .NET. I'm in a situation where, if programming in C#, I would throw a System.InvalidOperationException.

Before creating my own java.lang.RuntimeException subclass, I need to know if there is a similar exception type I should throw in Java.

The exact scenario is:

My class is a value object that provides an int intValue() method, returning an int. However, in some situations, the current value cannot be provided as an int, so this class also provides a boolean isInteger() to allow API users to know when intValue() can be safely invoked.

If a caller calls intValue() when isInteger() is false, an exception should be thrown.

And the question is: What type of exception?

I know that this question might not have a correct answer, but considering that I don't have lots of experience designing Java APIs, I want to know from other Java developers what they would expect to be thrown in this scenario.

thanks

Answer 1

Throw an IllegalStateException:

Signals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.