Calculator : Console Based Java Program

A calculator  is a small, portable, often inexpensive electronic device used to perform both basic and complex operations of arithmetic.

Here in this program we will create a console based calculator . Anyone can perform the basic operations in the calculator , i.e  add , subtract , multiply , divide .  

Here user needs ti input the two numbers and then need to press the number corresponding to the particular 
operation .

Read also  :        How to Create Random number in Java

Things to learn in this code 

Scanner scan= new Scanner(System.in) 
//sets up scanner string 

action=scan.nextLine();

//This is the code to read the inputs of the user from the console . Here System is the java class and in is the variable which means input .


It is good practice  to flush the object of the scanner class in the end of the class . Scanner class is mainly use to read the user inputs from the console . Although one can also use Console java class to achieve the same , but here we use scanner object .

To do it through console class ,We need to create the console class object

        Console console= System.console(); 

then read through each line through readLine() method

        String line = console.readLine();   

Pseudo Code :

1.  Menu is shown to select the operation 
2. If user inputs a 
                 then prompt the user to input the first number and second number
    else if user inputs s 
                 then prompt the user to input the first number and second number 

    else if user inputs m 
                 then prompt the user to input the first number and second number

    else if user inputs d 
                 then prompt the user to input the first number and second number       
3. Show the result       

Read Also :    Square root java swing code  with example


Demo 

Please find the code below :

import java.util.Scanner;    //imports scanners

public class Calc {
    
    public static void main(String[] args) {
        boolean go = true;    //sets up loop
        
        while(go)    //creates loop to top
        {
            System.out.println("Hello this is my calculator!");
            System.out.println("To add, type a, to subtract, type s.");
            System.out.println("To multiply, type m, to divide, type d.");
            
            Scanner scan = new Scanner(System.in);    //sets up scanners
            Scanner scan1 = new Scanner(System.in);
            
            
            String action = scan.nextLine();    //tells comp. to take user input
            
            if("a".equals(action))    //addition
            {
                System.out.println("Now type in the first number you would like to add.");
                int add1 = scan.nextInt();
                System.out.println("Now type the second number.");
                int add2 = scan.nextInt();
                int add3 = add1 + add2;
                System.out.println(add1 + " added to " + add2 + " equals " + add3 + "!");
            }
            if("s".equals(action))    //subtraction
            {
                System.out.println("Now type in the first number you would like to subtract.");
                int sub1 = scan.nextInt();
                System.out.println("Now type the second number.");
                int sub2 = scan.nextInt();
                int sub3 = sub1 - sub2;
                System.out.println(sub1 + " subtracted bye " + sub2 + " equals " + sub3 + "!");
            }
            if("m".equals(action))    //multiplacation
            {
                System.out.println("Now type in the first number you would like to multiply.");
                int mul1 = scan.nextInt();
                System.out.println("Now type the second number.");
                int mul2 = scan.nextInt();
                int mul3 = mul1 * mul2;
                System.out.println(mul1 + " multiplied bye " + mul2 + " equals " + mul3 + "!");
            }
            if("d".equals(action))    //division
            {
                System.out.println("Now type in the first number you would like to divide.");
                int div1 = scan.nextInt();
                System.out.println("Now type the second number.");
                int div2 = scan.nextInt();
                int div3 = div1 / div2;
                System.out.println(div1 + " divided bye " + div2 + " equals " + div3 + "!");
            }
            
            
            System.out.println("Would you like to start over? (yes,no)");
            String startOver = scan1.nextLine();
            
            if("no".equals(startOver))
            {
                go = false;
                System.out.println("Bye");
            }
        }
    }
}