Write your first program in Java

We are gonna write our very own first java program. In this article, while we uncover the program we will also learn a new concept called scanner class.

Before we head on to the programming part lets see what scanner class is.

Scanner class

A scanner class in java is nothing but a java util package utility to get the input from the user during runtime.

Syntax:

Scanner input = new Scanner(System.in);

Example

import java.util.Scanner;

public class Testing
{
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        
        System.out.print("Enter A Number : ");
        double numberOne = input.nextDouble();
        System.out.print("Enter Operator: ");
        String oP = input.next();
        System.out.print("Enter Another Number : ");
        double numberTwo = input.nextDouble();
        
        if (oP.equals("+"))
            System.out.println(numberOne+numberTwo);
        else if (oP.equals("-"))
            System.out.println(numberOne-numberTwo);
        else if (oP.equals("*"))
            System.out.println(numberOne*numberTwo);
        else if (oP.equals("/"))
           System.out.println(numberOne/numberTwo);
        else if (oP.equals("%"))
           System.out.println(numberOne%numberTwo);
        else
            System.out.println("Operator Not Found");
    }
}

Output:

Enter A Number : 50
Enter Operator: /
Enter Another Number : 500
0.1

Using the scanner class we have implemented a simple calculator program.
As we know scanner class gets input from users.
We are declaring it with object 'input'.
Now we are giving a sysout to print some random sentences in this case I have done 'enter a number'.
Now, the scanner class has many functions access by control+space there are many datatype functions under the scanner class.
It will be in the form on nextDouble, next, etc.
What it does is it fetches input from the user with that particular datatype and performs the rest of the action.
You can verify them from the return type.
Then I have used the if and elseif to do the necessary mathematical operations.
If the oP is equal to the user input given as +,-,*,/ etc
It will go through the if body and goes in the body of whatever the conditions satisfy based on user input.
Thus you can also your mathematical functions like this as well too.