Methods: Reusable Code

Write your own methods with parameters and return types to keep code neat.

🎯 What you will learn

Write static methods
Use parameters and return types
Call methods from main

👋 Let’s get started!

Methods are Java’s version of functions 🛠️. You give them a name, inputs and the TYPE of answer they return. Then call them as often as you like!

🪜 Step by step

1. 🛠️ A simple method

void means it doesn’t return anything.

static void cheer() {
    System.out.println("Hooray! 🎉");
}

2. 📥📤 Parameters & return

Say the return type before the name, and the parameter types inside ( ).

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

3. 📞 Calling

Call methods from main.

public static void main(String[] args) {
    cheer();
    System.out.println(add(4, 6));
}

🧪 Try it!

Read the code, guess what it prints, then press 👀 Show output.

Area calculator

public class Main {
    static int area(int w, int h) {
        return w * h;
    }

    public static void main(String[] args) {
        System.out.println("Room: " + area(5, 4));
        System.out.println("Garden: " + area(10, 7));
    }
}

Greeting method

static void greet(String name) {
    System.out.println("Hi " + name);
}

📖 Key words

Tap a card to flip it over!

Method: A named block of reusable code 🛠️
void: Returns nothing 🚫
Return type: The type of answer a method gives back 📤
Argument: The value you pass in when calling 📥

🏆 Challenge

Predict the output of this method call.

Challenge

static int triple(int n) {
    return n * 3;
}
// in main:
System.out.println(triple(9));

Knowledge Check Quiz

What does void mean?
What prints?
Which method returns a String?