Static methods in Java - Mini Project: Build & Apply

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Using Static Methods in Java

📖 Scenario: You are creating a simple calculator program that can add and multiply numbers. To keep things organized, you want to use static methods inside a class so you can call them without creating an object.

🎯 Goal: Build a Java class called Calculator with two static methods: add and multiply. Then call these methods from the main method to show the results.

📋 What You'll Learn

Create a class named Calculator

Add a static method add that takes two int parameters and returns their sum

Add a static method multiply that takes two int parameters and returns their product

In the main method, call Calculator.add and Calculator.multiply with the numbers 5 and 7

Print the results of both method calls

💡 Why This Matters

🌍 Real World

Static methods are used for utility functions like math calculations, formatting, or helper methods that don't need object data.

💼 Career

Understanding static methods is important for writing clean, reusable code and is commonly used in Java programming jobs.

1

Create the Calculator class

Create a public class called Calculator with an empty body.

Java

public class Calculator {
    // Your code here
}

💡 Need a hint?

Use the class keyword followed by the class name Calculator.

2

Add static methods add and multiply

Inside the Calculator class, add two public static methods: add and multiply. Both take two int parameters named a and b. add returns the sum of a and b. multiply returns the product of a and b.

Java

public class Calculator {
    // Add public static int add(int a, int b) method
    // Add public static int multiply(int a, int b) method
    // Your code here
}

💡 Need a hint?

Static methods use the static keyword and can be called without creating an object.

3

Add the main method to call static methods

Add a public static void main(String[] args) method inside the Calculator class. Inside it, call Calculator.add(5, 7) and store the result in an int variable named sum. Also call Calculator.multiply(5, 7) and store the result in an int variable named product.

Java

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

    public static int multiply(int a, int b) {
        return a * b;
    }

    // Add main method below
    // Your code here
}

💡 Need a hint?

The main method is the program's entry point. Use the class name to call static methods.

4

Print the results

Inside the main method, add two System.out.println statements to print the values of sum and product. The first line should print exactly Sum: 12 and the second line should print exactly Product: 35.

Java

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

    public static int multiply(int a, int b) {
        return a * b;
    }

    public static void main(String[] args) {
        int sum = Calculator.add(5, 7);
        int product = Calculator.multiply(5, 7);
        // Print sum and product below
        // Your code here
    }
}

💡 Need a hint?

Use System.out.println to print text and variables. Use + to join strings and variables.