Methods: Parameters and Return Values

A method is a reusable block of code that performs a specific task. Breaking a program into methods makes it modular, testable, and far easier to read and maintain than one giant block of code.

Basic Method Syntax

public static int add(int a, int b) {
    return a + b;
}

public static void main(String[] args) {
    int result = add(5, 3);
    System.out.println(result); // 8
}

Anatomy of a Method

Void Methods (No Return Value)

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

public static void main(String[] args) {
    greet("Vishwas"); // prints: Hello, Vishwas!
    // No result to store — void methods perform an action, they don't return data
}

Parameters vs Arguments

Parameters are the variables listed in the method definition. Arguments are the actual values passed in when calling the method.

public static int multiply(int x, int y) {  // x, y = parameters
    return x * y;
}

int result = multiply(4, 5);  // 4, 5 = arguments

Pass-by-Value Behavior

Java is strictly pass-by-value — when you pass a primitive (int, double, etc.) into a method, a copy is passed. Changes inside the method do not affect the original variable.

public static void tryToChange(int num) {
    num = 100; // only changes the local copy
}

public static void main(String[] args) {
    int x = 5;
    tryToChange(x);
    System.out.println(x); // still 5, NOT 100
}

Interview tip: For objects and arrays, the reference is copied, not the object itself — so modifying an array's contents inside a method DOES affect the original array, even though Java is technically still "pass-by-value" (it's the reference value being copied).