calculator function in java code example

Example 1: how to make a calculator in java

// this was all coded by me, to use it get Eclipse, or IntelliJ and make a new
// Java Project

package javaCode;

import java.util.Scanner;

public class testCode {

	public static void main(String[] args) {
		
		Scanner scan = new Scanner(System.in);
		
		System.out.println("Would you like to Add, Subtract, Divide, or Multiply?");
		
		String mathType = scan.next();
		
		if (mathType.equalsIgnoreCase("add")) {
			System.out.println("Whats the first number you want to add?");
			
			int firstNumber = scan.nextInt();
			
			System.out.println(firstNumber + " + ");
			System.out.println("Enter your second number");
			
			int secondNumber = scan.nextInt();
			
			System.out.println(firstNumber + " + " + secondNumber + " =");
			System.out.println(firstNumber + secondNumber);
			
		} else if (mathType.equalsIgnoreCase("subtract")) {
			System.out.println("Whats the first number you want to subtract?");
			
			int firstNumber = scan.nextInt();
			
			System.out.println(firstNumber + " - ");
			System.out.println("Enter your second number");
			
			int secondNumber = scan.nextInt();
			
			System.out.println(firstNumber + " - " + secondNumber + " =");
			System.out.println(firstNumber - secondNumber);
		} else if (mathType.equalsIgnoreCase("divide")) {
			System.out.println("Whats the first number you want to divide?");
			
			int firstNumber = scan.nextInt();
			
			System.out.println(firstNumber + " % ");
			System.out.println("Enter your second number");
			
			int secondNumber = scan.nextInt();
			
			System.out.println(firstNumber + " % " + secondNumber + " =");
			System.out.println(firstNumber / secondNumber);
		} else if (mathType.equalsIgnoreCase("multiply")){
			System.out.println("Whats the first number you want to multiply?");
			
			int firstNumber = scan.nextInt();
			
			System.out.println(firstNumber + " x ");
			System.out.println("Enter your second number");
			
			int secondNumber = scan.nextInt();
			
			System.out.println(firstNumber + " x " + secondNumber + " =");
			System.out.println(firstNumber * secondNumber);
		}
		
	}

}

Example 2: java calculator

package main;

import java.util.Scanner;

public class calculator {

    public static void greetings(){
        System.out.println("Hi welcome to the calculator made by Pepa pig made in java! :D");
    }

    public static void instruction(){
        System.out.println("Hi welcome to the calculator made by Pepa pig made in java! :D");
    }

    public static void calculator(){
        Scanner keyboardInput = new Scanner(System.in);
        String calculator;

        do {
            System.out.print("Enter your first digit: ");
            double num1 = keyboardInput.nextDouble();

            System.out.print("Enter your operator: ");
            String op = keyboardInput.next();

            System.out.print("Enter your second digit: ");
            double num2 = keyboardInput.nextDouble();

            System.out.print("= ");

            if (op.equals("+")){
                System.out.print(num1 + num2);
                System.out.println("\nYou were adding");
                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
            }else if (op.equals("-")){
                System.out.print(num1 - num2);
                System.out.println("\nYou were subtracting");
                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
            }else if (op.equals("*")){
                System.out.print(num1 * num2);
                System.out.println("\nYou were multiplying");
                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
            }else if (op.equals("/")){
                System.out.print(num1 / num2);
                System.out.println("\nYou were dividing");
                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
            }else if (op.equals("%")){
                System.out.print(num1 % num2);
                System.out.println("\nYou were remanding");
                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
            }else{
                System.out.println("Invalid operator");
            }
            System.out.print("Would you like to restart the calculator? (y or n): ");
            calculator = keyboardInput.next();
        }
        while (calculator.equals("y"));

        if (calculator.equals("n")){
            System.out.println("Leave then kiddo ;-;");
        }
    }


    public static void main(String[] args) {
        greetings();
        instruction();
        calculator();
    }
}