How to Re-throw an InvocationTargetException in Java?

How can I re-throw an InvocationTargetException in Java?

try {
    // code that might throw an InvocationTargetException
} catch (InvocationTargetException e) {
    throw e.getCause();
}

In Java, the `InvocationTargetException` is thrown when a method invoked via reflection throws an exception. This exception wraps the original exception that occurred during the method invocation. Understanding how to re-throw this exception is essential for proper error handling in reflective operations.

try {
    Method method = SomeClass.class.getMethod("someMethod");
    method.invoke(instance);
} catch (InvocationTargetException e) {
    Throwable cause = e.getCause();
    if (cause instanceof SomeSpecificException) {
        throw new CustomException(cause);
    } else {
        throw new RuntimeException(cause);
    }
}

Causes

• The method being invoked via reflection throws an exception.
• InvocationTargetException is a wrapper for the original exception.

Solutions

• Use a try-catch block to catch `InvocationTargetException` and re-throw the underlying cause using `getCause()`.
• Ensure that the exception being re-thrown is checked or handled according to your application's requirements.

Mistake: Catching `Exception` instead of `InvocationTargetException` which obscures the error.

Solution: Always catch the specific exception related to reflection to understand the error better.

Mistake: Not using `getCause()` which results in throwing the `InvocationTargetException` itself instead of the original exception.

Solution: Use `e.getCause()` to retrieve and re-throw the original exception from the target.