01-Introduction-to-Exceptions-in-Java.md

Introduction to Exceptions in Java

What is an Exception?

• An exception is an event that disrupts the normal flow of a program.
• It occurs at runtime when something unexpected happens, such as invalid input, division by zero, or trying to access a file that does not exist.

Why Exceptions are Important

• They help us handle errors gracefully instead of crashing the program.
• They make code easier to understand and debug.
• They allow the programmer to separate normal logic from error-handling logic.

Types of Exceptions in Java

1. Checked Exceptions

• These are checked at compile time.
• Example: IOException, SQLException

2. Unchecked Exceptions

• These occur at runtime.
• Example: ArithmeticException, NullPointerException, ArrayIndexOutOfBoundsException

3. Errors

• Serious problems that are usually not handled by the program.
• Example: OutOfMemoryError, StackOverflowError

Basic Syntax

try { // code that may cause an exception } catch (ExceptionType e) { // handle the exception } finally { // code that always executes }

Example

public class ExceptionExample { public static void main(String[] args) { try { int a = 10; int b = 0; int result = a / b; System.out.println(result); } catch (ArithmeticException e) { System.out.println("Cannot divide by zero"); } finally { System.out.println("This block always runs"); } } }

Important Keywords

• try: contains code that may throw an exception
• catch: handles the exception
• finally: executes regardless of whether an exception occurs
• throw: manually throws an exception
• throws: declares that a method may throw an exception

Summary

• Exceptions are used to handle runtime problems.
• Java provides try, catch, finally, throw, and throws keywords.
• Proper exception handling improves program reliability and user experience.