Methods

he Concept: The "Black Box"

A method is a self-contained block of code that performs a specific task. Imagine a Toaster.

1. Input: You put in bread (this is called a Parameter).

2. Action: The toaster heats it up (the Logic).

3. Output: It pops out toast (the Return Value).

You don't need to know how the toaster works every time; you just need to know what to give it and what you’ll get back.

The Anatomy of a Method

A standard method looks like this: public static returnType methodName(parameters) { ... }

• returnType: What kind of data comes out? If nothing comes out, we use void. If a number comes out, we use int.

• methodName: The name we use to call it (e.g., calculateTax).

• parameters: The inputs the method needs to do its job.

• return keyword: This sends the final result back to whoever called the method.

The Code Example:

public class MethodsDemo {

    // 1. A method that takes two numbers and RETURNS their sum
    // It is 'static' so we can call it directly from main
    public static int addNumbers(int a, int b) {
        int result = a + b;
        return result; // Sending the answer back
    }

    // 2. A method that takes a String and returns NOTHING (void)
    // It just performs an action (printing)
    public static void greetUser(String name) {
        System.out.println("Hello, " + name + "! Welcome to Topic 6.");
    }

    public static void main(String[] args) {
        // Calling the greeting method
        greetUser("Alice");
        greetUser("Bob");

        // Calling the math method and storing the result in a variable
        int total = addNumbers(25, 75);
        System.out.println("The sum of 25 and 75 is: " + total);

        // We can also call it directly inside a print statement
        System.out.println("Quick Math (5+5): " + addNumbers(5, 5));
    }
}

Expected Output:

Hello, Alice! Welcome to Topic 6.
Hello, Bob! Welcome to Topic 6.
The sum of 25 and 75 is: 100
Quick Math (5+5): 10

Methods are the foundation of DRY (Don't Repeat Yourself) programming.

1. Organization: Your code is easier to read.

2. Reusability: Write once, use a million times.

3. Debugging: If the math is wrong, you only have to fix it in one place (the method), not in fifty different places throughout your app.

Pro Tip: In Java, we use camelCase for method names (e.g., calculateFinalScore). It starts with a lowercase letter, and every word after starts with an uppercase letter.