Simple Calculator in java

In this page, we will learn to build a simple calculator application in java

Step 1 : Create interface Calculation.java

package com.javatrainingschool.service;

public interface Calculation {
	
	public int addNumbers(int num1, int num2);
	
	public int subtractNumbers(int num1, int num2);
	
	public int multiplyNumbers(int num1, int num2);
	
	public int divideNumbers(int num1, int num2) throws ArithmeticException;

}

Step 2 : Create implementation class

package com.javatrainingschool.service;

import java.util.List;

public class CalculationImpl implements Calculation {

	@Override
	public int addNumbers(int num1, int num2) {
		
		return num1 + num2;
	}

	@Override
	public int subtractNumbers(int num1, int num2) {
		return num1 - num2;
	}

	@Override
	public int multiplyNumbers(int num1, int num2) {
		
		return num1 * num2;
	}

	@Override
	public int divideNumbers(int num1, int num2) throws ArithmeticException{
		return num1 / num2;
	}
}

Step 3 : Create the main class

package com.javatrainingschool.service;

import java.util.Scanner;

public class CalculationMainClass {
	
	private static Calculation calculation = new CalculationImpl();
	
	public static void main(String[] args) {
		
		System.out.println("Welcome to Java Calculator Application");
		
		System.out.println("Choose which operation you want to perform");
		System.out.println("1. Addition");
		System.out.println("2. Subtraction");
		System.out.println("3. Multiplication");
		System.out.println("4. Division");
		
		System.out.println("Enter the operation Number : ");
		
		Scanner sc = new Scanner(System.in);
		String input = sc.nextLine();
		
		System.out.println("Enter the num1 : ");
		int num1 = sc.nextInt();
		
		System.out.println("Enter the num2 : ");
		int num2 = sc.nextInt();
		
		
		
		int result = processInput(input, num1, num2);
		
		System.out.println("The result of the operation is : " + result);
		
		sc.close();
		
	}
	
	public static int processInput(String input, int num1, int num2) {
		
		int result = 0;
		
		switch(input){
		case "1" : 
			result = calculation.addNumbers(num1, num2);
			break;
		case "2" : 
			result = calculation.subtractNumbers(num1, num2);
			break;
		case "3" : 
			result = calculation.multiplyNumbers(num1, num2);
			break;
		case "4" : 
			result = calculation.divideNumbers(num1, num2);
		}
		return result;
	}
}

Output :

Welcome to Java Calculator Application
Choose which operation you want to perform
1. Addition
2. Subtraction
3. Multiplication
4. Division
Enter the operation Number : 
3
Enter the num1 : 
34
Enter the num2 : 
5
The result of the operation is : 170