Recursion & Varargs

Recursion

Recursion is when a method calls itself. It's a powerful technique for solving problems that can be broken down into smaller, similar sub-problems.

Anatomy of Recursion

1. Base Case: The condition that stops the recursion
2. Recursive Case: The method calls itself with a modified parameter

public int factorial(int n) {
    // Base case
    if (n == 0 || n == 1) {
        return 1;
    }
    // Recursive case
    return n * factorial(n - 1);
}

Common Recursive Problems

• Factorial calculation
• Fibonacci sequence
• Tree traversal
• Directory scanning

[!WARNING] Without a proper base case, recursion leads to StackOverflowError!

Varargs (Variable Arguments)

Varargs allow you to pass a variable number of arguments to a method.

Syntax

public void printNumbers(int... numbers) {
    for (int num : numbers) {
        System.out.println(num);
    }
}

Rules

• Varargs must be the last parameter
• Only one varargs parameter per method
• Treated as an array inside the method

Quiz