throw vs throws in Java
throw and throws are two Java keywords related to the Exception feature of the Java programming language. If you are writing a Java program and familiar with What is Exception in Java, it's a good chance that you are aware of What is throw and throws in Java. In this Java tutorial, we will compare throw vs throws and see some worth noting differences between throw and throws in Java. Exception handling is an important part of the Java programming language which enables you to write robust programs. There are five keywords related to Exception handling in Java like try, catch, finally, throw, and throws.
Apart from the difference between final, finally, and finalize, throw vs throws is one of the frequently asked Java interview questions. The difference listed here will not only help you to answer this interview question but also understand the concept behind throw and throws better.
Difference between throw and throws in Java
Without wasting any more of your time, here is a list of key differences between the throw and throws keywords in Java. Even though both are related to errors and exceptions in Java, there are some subtle differences that are listed here.
1. Purpose
The throw keyword is used to throw Exception from any method or static block in Java while throws keyword, used in the method declaration, denoted which Exception can possibly be thrown by this method.
2.Handling
If any method throws a checked Exception as shown in the below Example, then the caller can either handle this exception by catching it or can re-throw it by declaring another throws clause in the method declaration.
public void read() throws IOException{
throw new IOException();
}
failure to either catch or declaring throws in method signature will result in compile time error.
3. Usage
The throw keyword can be used in the switch case in Java but the throws keyword can not be used anywhere except on the method declaration line.
4. Overloading
As per Rules of overriding in Java, the overriding method can not throw Checked Exception higher in the hierarchy than the overridden method. This is the rule for throws clause while overriding a method in Java.
5. Eligibility
Both Checked and Unchecked Exception can be declared to be thrown using the throws clause in Java.
6. Control
The throw keyword transfers control to the caller while throws are suggesting for information and compiler checking. See these free Java Programming courses to learn more about throw, throws, and in-general exception handling in Java.
That's all on the difference between throw vs throws in Java and Exception handling. You must try some examples to use throw and throws as well and rather importantly you must know when to use the throw and throws keyword in Java. In summary, use throw to actually throw an exception which will give control back to the caller, and use throws to declare which Exception can be thrown by a particular method, which allows the caller to handle them.
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