Java Methods - Java Technology | BigXStar

What is a Method?

A method is a reusable block of code that performs a specific task. Methods help organize code, avoid repetition, and make programs easier to read and maintain.

java

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

// Method call
int result = add(5, 3);  // result = 8

Method Syntax

java

accessModifier returnType methodName(parameterList) {
    // method body
    return value;  // if returnType is not void
}

Part	Description	Example
Access Modifier	Visibility level	`public`, `private`, `protected`
Return Type	Type of value returned	`int`, `String`, `void`
Method Name	Name to call the method	`calculateTotal`
Parameters	Input values	`(int a, int b)`

Methods with Return Values

java

public static double calculateArea(double radius) {
    return Math.PI * radius * radius;
}

public static String greet(String name) {
    return "Hello, " + name + "!";
}

public static void main(String[] args) {
    double area = calculateArea(5.0);
    System.out.printf("Area: %.2f%n", area);       // Area: 78.54

    String message = greet("Arjun");
    System.out.println(message);                     // Hello, Arjun!
}

Void Methods

Methods that don't return a value use void:

java

public static void printLine(int length) {
    for (int i = 0; i < length; i++) {
        System.out.print("─");
    }
    System.out.println();
}

public static void main(String[] args) {
    printLine(30);
    System.out.println("Java Methods Tutorial");
    printLine(30);
}

Method Overloading

Multiple methods with the same name but different parameters:

java

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

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

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

public static void main(String[] args) {
    System.out.println(add(5, 3));         // 8 (int version)
    System.out.println(add(2.5, 3.7));     // 6.2 (double version)
    System.out.println(add(1, 2, 3));      // 6 (three-param version)
}

Variable Arguments (Varargs)

Accept a variable number of arguments:

java

public static int sum(int... numbers) {
    int total = 0;
    for (int n : numbers) {
        total += n;
    }
    return total;
}

public static void main(String[] args) {
    System.out.println(sum(1, 2));           // 3
    System.out.println(sum(1, 2, 3, 4, 5));  // 15
}

Recursion

A method that calls itself:

java

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

public static void main(String[] args) {
    System.out.println(factorial(5));   // 120 (5×4×3×2×1)
}

Practical Example

java

public class MathUtils {
    public static boolean isPrime(int n) {
        if (n < 2) return false;
        for (int i = 2; i <= Math.sqrt(n); i++) {
            if (n % i == 0) return false;
        }
        return true;
    }

    public static void printPrimes(int start, int end) {
        System.out.printf("Primes between %d and %d: ", start, end);
        for (int i = start; i <= end; i++) {
            if (isPrime(i)) {
                System.out.print(i + " ");
            }
        }
        System.out.println();
    }

    public static void main(String[] args) {
        printPrimes(1, 50);
    }
}

Output:

Primes between 1 and 50: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

Summary

Methods are reusable blocks of code defined with a return type, name, and parameters
Use void for methods that don't return a value
Method overloading allows same-name methods with different parameter lists
Varargs (int... numbers) accept variable-length arguments
Recursion is when a method calls itself — always need a base case
Follow naming convention: camelCase for method names (e.g., calculateTotal)