? Java Exceptions

? Quick Overview

Exceptions in Java represent abnormal conditions that interrupt the normal flow of a program. Java provides a powerful exception-handling mechanism using predefined classes and keywords.

? Key Concepts

• Exception is an object that represents an error
• All exceptions inherit from Throwable
• Handled using try, catch, finally
• Can be checked or unchecked

? Syntax / Theory

Java exceptions are broadly classified into:

• Checked Exceptions – Checked at compile time
• Unchecked Exceptions – Occur at runtime
• Errors – Serious issues not meant to be handled

? Code Example

// Example of ArithmeticException
public class ExceptionDemo {
    public static void main(String[] args) {
        int a = 10;
        int b = 0;
        System.out.println(a / b);
    }
}

?️ Live Output / Explanation

? Common Types of Java Exceptions

• ArithmeticException – Thrown when an exceptional arithmetic condition occurs (e.g., integer division by zero).
• NullPointerException – Thrown when an application attempts to use null in a case where an object is required.
• ArrayIndexOutOfBoundsException – Thrown when trying to access an array with an illegal index (negative or outside the size).
• StringIndexOutOfBoundsException – Thrown by String methods to indicate that an index is either negative or greater than the size of the string.
• NumberFormatException – Thrown when attempting to convert a string (like "abc") into a numeric type (like int) but the format is invalid.
• ClassNotFoundException – Thrown when an application tries to load a class through its string name, but the class cannot be found.
• IOException – Signals that an Input/Output exception of some sort has occurred (e.g., reading/writing errors).
• SQLException – An exception that provides information on a database access error or other errors related to SQL.
• FileNotFoundException – Signals that an attempt to open a file denoted by a specified pathname has failed because the file does not exist.
• InterruptedException – Thrown when a thread is waiting or sleeping and is interrupted by another thread.