Runtime vs. Checked Exceptions: When Should You Extend RuntimeException?

Runtime and Checked Exceptions: Java's Exception Hierarchy

In Java, exceptions are essential for handling unexpected events during program execution. Understanding the difference between runtime and checked exceptions is crucial when designing your exception hierarchy.

Java.lang.RuntimeException and java.lang.Exception form the cornerstone of this hierarchy. RuntimeException represents exceptions that are unchecked by the compiler, while Exception denotes checked exceptions.

Deciding Which One to Extend:

When creating your own exception, the choice between RuntimeException and Exception depends on the following factors:

• Programmatic Preventability: If the exception can be prevented through proper programming, such as index out of bounds or null pointers, extend RuntimeException.
• Responsibility: If the exception is caused by internal program logic or faulty user input, extend Exception. This forces callers to handle the exception explicitly at compile time.

Historical Preferences:

Traditionally, people preferred to extend Exception for most cases. However, in recent years, there has been a shift towards using RuntimeException. This is because RuntimeException results in cleaner code by allowing unchecked exceptions to propagate without the need for try-catch blocks.

Example:

Suppose you want to create an exception for an invalid file path in your file handling program. Since the file path is determined by external user input, you would extend Exception:

<code class="java">public class InvalidFilePathException extends Exception {
    // Constructor to pass custom message
}</code>

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