Difference between Throw and Throws in Java
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When we need to throw an exception manually, we use the 'throw' keyword which indicates a problem with code execution. It is followed by an instance of Throwable. On the other hand, the throws keyword is used with the method declarations to indicate exceptions that the method may throw, which callers must manage or disclose. Both improve code dependability.
For the prerequisites, go through throw and throws in Java.
| Feature | throw | throws |
|---|---|---|
| Purpose | When there is a need to explicitly throw an exception. | Used to declare exceptions that a method might throw. |
| Syntax | Used as a statement followed by an exception object. | Used in method signature followed by the exception classes. |
| Applicability | Used within a method or block to raise an exception. | Used in a method declaration to indicate potential exceptions. |
| Single Exception Handling | Can handle only one exception at a time. | Can declare multiple exceptions separated by commas. |
| Execution Flow | Stops execution of the current method and looks for a catch block. | Allows the method to propagate the exception to the caller. |
| Error Handling | Essential for handling exceptions in try-catch blocks. | Provides information to callers about potential exceptions. |
Java throw Example
When programming with Java, you may encounter instances in which you must handle errors or odd events. One way to deal with these situations is to utilize the throw keyword. Let's look at an example to see how things function.
Here's a simple code snippet demonstrating the throw keyword in action:
In this instance, the DivisionExample class contains a main function. Within the main code, we have two variables: dividend and divisor, with the divisor intentionally set to zero to generate an error.
We then encapsulate the division operation in a try block. In the try block, we check if the divisor is zero. If it is, we raise an ''ArithmeticException'' using the throw keyword and a detailed description.
The catch block collects the exception and outputs an error message.
Java throws Example
In Java, the term 'throws' is used in method declarations to define the exceptions that may occur within that method. It informs the compiler that this function may throw specific exceptions during execution.
Example of using 'throws':
In this example, the readFile() method declares that it might throw a FileNotFoundException.This means that if someone uses this function, they will need to catch the exception or use another 'throws' declaration in their method to handle it.
When you want to pass exception handling to the caller method, use 'throws'. This is useful when the method cannot adequately handle the exception and requires the caller method to do so.
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Conclusion
- 'throw' is used to manually throw an exception within a method, whereas 'throws' is used in the method signature to specify the kind of exceptions that can be thrown.
- When you use 'throw', you are stating clearly that an exception is being thrown at that moment in your code. On the other hand, 'throws' just indicates that the method may throw an exception at any time during its execution.
- The 'throw' keyword is used within a method body to throw an exception that affects just that method's execution. On the other hand, the 'throws' keyword is used to indicate that the method has thrown an exception to the caller.
- When you use 'throw', you take direct responsibility for throwing an exception, which is usually triggered when a specified condition is satisfied or an error occurs. However, 'throws' delegated exception handling to the caller or higher-level procedures.
- Using 'throw' enables more exact control over the exception handling within the method, such as custom error messages or particular exception kinds. 'throws', on the other hand, allows you to express potential exceptions to calling methods and let them determine how to handle them.