What is the purpose of using the throw keyword in Java?

The “throw” keyword in Java is used to manually throw an exception. Its purpose is to explicitly throw an exception in the program, redirecting the program’s execution flow to the exception handling code when an error or exception occurs. By using the throw keyword, you can throw checked or unchecked exceptions anywhere in the program.

The ‘throw’ keyword can be used to achieve the following functionalities:

1. Throwing custom exceptions: Custom exception handling mechanisms can be implemented by creating a custom exception class and using the throw keyword to throw the exception in the code.
2. Throw standard exceptions: You can use the throw keyword to throw pre-defined standard exceptions in Java, such as NullPointerException, IllegalArgumentException, and so on.
3. Terminate program execution: By using the throw keyword in the code to throw exceptions, the normal flow of the program can be interrupted and the program can be terminated prematurely.

It is important to note that if an exception is thrown in a method using the throw keyword, the caller of the method must either use a try-catch block or continue using the throw keyword to rethrow the exception upwards in order to properly handle the exception in the code.