How Does Exception Handling Work for RuntimeException in Java?

How does exception handling work for RuntimeException in Java?

catch (Exception exc) { /* won't catch RuntimeException */ }

In Java, the exception handling mechanism is based on a hierarchy of classes, with Exception being a checked exception and RuntimeException being an unchecked exception. Understanding the distinction between these two is crucial for proper error handling in applications.

for (Callback cb : callbacks) {
    try {
        cb.call(item);
    } catch (Exception exc) { 
        logger.error("Error in callback: ", exc);
    }
}

Causes

• RuntimeException is a subclass of Exception and is therefore part of its hierarchy.
• The distinction lies in the fact that RuntimeExceptions are unchecked exceptions, meaning they do not need to be declared in method signatures and are not enforced at compile time.

Solutions

• To catch both checked and unchecked exceptions, use a larger scope of exception types such as Throwable, which encompasses all exceptions.
• For specific cases where only RuntimeExceptions are expected but you want to provide isolation among callbacks, you can catch Exception for checked exceptions and handle RuntimeException separately.
• Alternatively, consider implementing a custom callback interface that includes error handling for the specific situations you're encountering.

Mistake: Catching Exception but not RuntimeException when necessary.

Solution: Make sure to catch RuntimeException if you want to handle it specifically or ensure that critical failures are considered.

Mistake: Assuming catching Throwable provides no additional issues than catching Exception.

Solution: Catching Throwable can mask serious errors, such as OutOfMemoryError; use it judiciously.