Recursive method in Java

Recursive method in Java – A method call by itself is called as Recursive method.

Method Parameters

Method parameters are the values that you pass to a method when you call it. These parameters are used by the method to perform operations.

Example:

public class Example {
    public static void greet(String name) {
        System.out.println("Hello, " + name);
    }

    public static void main(String[] args) {
        greet("Alice");  // Passing "Alice" as a parameter
    }
}

Explanation

• greet(String name) is a method with a parameter name of type String.
• When greet("Alice") is called, “Alice” is passed to the name parameter, and the method prints “Hello, Alice”.

Method Overloading in Java

Method overloading allows a class to have more than one method with the same name, but with different parameters (different type, number, or both).

Example:

public class Example {
    public static void print(int num) {
        System.out.println("Number: " + num);
    }

    public static void print(String str) {
        System.out.println("String: " + str);
    }

    public static void main(String[] args) {
        print(10);         // Calls print(int num)
        print("Hello");    // Calls print(String str)
    }
}

Explanation:

• There are two methods named print, one that takes an int parameter and another that takes a String parameter.
• Depending on the argument type, the appropriate method is called.

Method Scope

Method scope refers to the visibility and lifetime of variables defined within a method. Variables declared within a method are local to that method and cannot be accessed outside of it.

Example:

public class Example {
    public static void display() {
        int number = 10;  // Local variable
        System.out.println("Number: " + number);
    }

    public static void main(String[] args) {
        display();
        // System.out.println(number);  // This would cause a compile-time error
    }
}

Explanation:

• The variable number is declared within the display method and is local to that method.
• Attempting to access number outside of the display method (e.g., in main) will result in a compile-time error.

Recursive Method in Java

A recursive method is a method that calls itself in order to solve a problem. Each recursive call should progress towards a base case that stops the recursion.

Example:

public class Example {
    public static int factorial(int n) {
        if (n == 0) {
            return 1;  // Base case
        } else {
            return n * factorial(n - 1);  // Recursive call
        }
    }

    public static void main(String[] args) {
        int result = factorial(5);  // 5! = 5 * 4 * 3 * 2 * 1 = 120
        System.out.println("Factorial of 5: " + result);
    }
}

Explanation:

• The factorial method calculates the factorial of a given number n recursively.
• If n is 0, the base case returns 1.
• Otherwise, it returns n * factorial(n - 1), which is a recursive call to calculate the factorial of n - 1.

These concepts form the foundation of method usage in Java. Understanding them is crucial for writing efficient and maintainable code.