Lesson 14: Defining and Calling Methods

Methods define the behaviors or actions that an object can perform.

1. Method Structure (Signature)

A method signature consists of the method name and the type and number of its parameters. The full declaration also includes access modifiers, return type, and body.

Structure: AccessModifier Static/Non-Static ReturnType MethodName(Parameter List) { // Body }

java public class Calculator {

// Method 1: No parameters, returns nothing (void)
public void printWelcome() {
    System.out.println("Welcome to the Calculator");
}

// Method 2: Takes two int parameters, returns an int
public int add(int num1, int num2) {
    int result = num1 + num2;
    return result; // Must return a value matching the return type (int)
}

}

2. The return Keyword

• If a method has a return type (e.g., int, String, Dog), it must use return to send a value back to the caller.
• If the method returns void, return is optional (used only to exit the method early).

3. Calling Methods

To call a non-static method, you must first create an instance (object) of the class.

java Calculator calc = new Calculator();

// Calling a void method calc.printWelcome();

// Calling a method that returns a value int sum = calc.add(15, 7); System.out.println("The sum is: " + sum); // Output: 22

Note: If a method is declared static, you call it directly using the Class name (e.g., Calculator.addStatic(...)), without needing an object instance.