Description: IllegalArgumentException is an exception in Java that is thrown to indicate that a method has received an illegal or inappropriate argument. This exception is part of the Java exception hierarchy and is found in the java.lang package. Its purpose is to help developers identify errors in data input, ensuring that methods are used correctly. When a method receives an argument that does not meet expectations, such as a null value when not allowed, or a number outside an acceptable range, this exception is thrown. This allows programmers to handle errors more effectively and maintain application integrity. IllegalArgumentException is a subclass of RuntimeException, meaning it does not need to be declared in the method signature, allowing for greater flexibility in programming. Its use is common in parameter validation in public methods, where arguments are expected to meet certain conditions before the method executes. By throwing this exception, a message describing the issue is provided, facilitating debugging and improving the developer experience.
Examples: An example of IllegalArgumentException could be a method that processes numerical inputs for an operation. If a negative number is passed as an argument where only non-negative numbers are acceptable, the method could throw IllegalArgumentException to indicate that the argument is inappropriate. Another case could be a method that expects an index within a specific range; if an index outside that range is provided, this exception would be thrown to signal the error in the input.
