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Practice Programs · Lesson 138 of 150

Exception Handling Programs

Practicing exception handling scenarios builds confidence in writing safe, robust code that doesn't crash unexpectedly on bad input or unusual conditions.

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Why practice these?

Practicing exception handling scenarios builds confidence in writing safe, robust code that doesn't crash unexpectedly on bad input or unusual conditions.

Program 1: Handle Division by Zero Safely

java
import java.util.Scanner;

public class SafeDivision {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter numerator: ");
        int a = sc.nextInt();
        System.out.print("Enter denominator: ");
        int b = sc.nextInt();

        try {
            System.out.println("Result: " + (a / b));
        } catch (ArithmeticException e) {
            System.out.println("Error: Cannot divide by zero.");
        }
    }
}

Output (when denominator entered is 0):

Enter numerator: 10
Enter denominator: 0
Error: Cannot divide by zero.

Program 2: Custom Exception for Invalid Age

java
class InvalidAgeException extends Exception {
    InvalidAgeException(String message) {
        super(message);
    }
}

public class AgeValidation {
    static void validateAge(int age) throws InvalidAgeException {
        if (age < 0 || age > 120) {
            throw new InvalidAgeException("Age must be between 0 and 120");
        }
        System.out.println("Valid age: " + age);
    }

    public static void main(String[] args) {
        try {
            validateAge(150);
        } catch (InvalidAgeException e) {
            System.out.println("Error: " + e.getMessage());
        }
    }
}

Output:

Error: Age must be between 0 and 120

Key Points to Remember

  • Always validate user input before processing it, especially for values that could cause runtime exceptions.
  • Custom exceptions make error messages clearer and more specific to your application's actual rules.
  • Practicing multiple catch blocks for different exception types builds confidence in handling varied error scenarios.

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