Java Exception Handling | Exception Handling

1. Introduction

Exception handling is a powerful mechanism in Java that allows the program to deal with unexpected errors gracefully. Instead of crashing, the program can catch these errors and handle them appropriately.

2. Key Concepts

Exception: An event that disrupts the normal flow of the program.
Error: A serious problem that a reasonable application should not try to catch.
Throwing an Exception: Using the throw keyword to trigger an exception.
Catching an Exception: Using try-catch blocks to handle exceptions.

3. Types of Exceptions

Java categorizes exceptions into two main types:

Checked Exceptions: Exceptions that must be either caught or declared in the method signature. Example: IOException.
Unchecked Exceptions: Runtime exceptions that do not need to be declared or caught. Example: NullPointerException.

4. Try-Catch Blocks

To handle exceptions, we use try-catch blocks. Here’s a basic example:


try {
    int result = 10 / 0; // This will throw an ArithmeticException
} catch (ArithmeticException e) {
    System.out.println("Cannot divide by zero!");
}

In this example, the division by zero is caught, and a message is printed instead of crashing the program.

5. Best Practices

Tip: Always catch the most specific exception first before more general exceptions.

Always clean up resources in a finally block.
Use custom exceptions for application-specific errors.
Avoid using exceptions for control flow.

6. FAQ

What is the difference between an Error and an Exception?

An Error is a serious issue that a reasonable application should not try to catch, while an Exception is an event that can be caught and handled.

Can we use multiple catch blocks?

Yes, you can catch multiple exceptions using separate catch blocks for each exception type.

What is a finally block?