DSA Exception Handling

Exception: An event that disrupts the normal flow of a program (e.g., divide by zero, accessing an invalid array index, etc.).
Exception Handling: Process of handling runtime errors gracefully without crashing the program.

try-catch Block
- Code that may throw an exception is written inside the try block.
- Exceptions are caught and handled in the catch block.

try {
	//Code that may throw an exception
} catch (ExceptionType e){
	//Handling code
}

finally Block
- Used for cleanup operations, e.g., closing files or database connections.
- Always executed, whether an exception is thrown or not.

try {
 // code that may throw exceoption
} catch (ExceptionType e) {
 // Handling code
} finally {
 // cleamup code
}

throw vs throws
- throw: Ek specific exception ko manually throw karte hain.
- throws: Method ke declaration mein batate hain ki ye method kaunse exception throw kar sakta hai.

void myMethod() throws IOException { 
	throw new IOException("File not found"); 
}

Types of Exceptions

Checked Exceptions
- Compile-time pe catch karna padta hai, warna code chalega nahi.
- Example: IOException, SQLException.
Unchecked Exceptions
- Runtime pe hoti hain, jaise NullPointerException, ArithmeticException.

public class ExceptionExample {
    public static void main(String[] args) {
        try {
            int[] arr = {1, 2, 3};
            System.out.println(arr[5]); // Error: ArrayIndexOutOfBoundsException
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Invalid index accessed!");
        }
    }
}

public class FinallyExample {
    public static void main(String[] args) {
        try {
            int data = 10 / 0;
        } catch (ArithmeticException e) {
            System.out.println("Error: " + e.getMessage());
        } finally {
            System.out.println("Cleanup: Closing resources");
        }
    }
}

throw and throws Example

import java.io.IOException;

public class ThrowExample {
    static void checkFile() throws IOException {
        throw new IOException("File not found!");
    }

    public static void main(String[] args) {
        try {
            checkFile();
        } catch (IOException e) {
            System.out.println("Caught Exception: " + e.getMessage());
        }
    }
}