Java Program To Add Two Numbers (Scanner) For Freshers

1. Overview

In this tutorial, You'll learn writing a java program to add two numbers for freshers or fresh graduates. This program shows how to find the sum of two numbers in a java programming language. This is a very basic when we learn any language first. So, We will see how to do sum for two numbers using '+' symbol directly and next will read the values from user input and do the sum.

2. Sum of two numbers example in java

package com.javaprogramto.engineering.programs;

public class SumOfTwoNumbers {

 public static void main(String[] args) {

  int number1 = 10;
  int number2 = 20;

  int sum = number1 + number2;

  System.out.println("Sum of two numbers (" + number1 + ", " + number2 + ") = " + sum);
 }
}

Output:

Sum of two numbers (10, 20) = 30

Here taken two int type variables number1 and number2 which stores the values 10 and 20. Then, using arithmetic formula number1 + number2 using '+' operator and the produced result is stored in the int type sum variable. Finally, result is printed on the console using System.out.println() method.

3. Another famous Example on Sum of two numbers with Scanner

Scanner is a final class that is introduced in Java 1.5 to read the input from the user. A simple text scanner which can parse primitive types and strings using regular expressions. System.in indicates that input for this scanner is provided through input devices such as a keyboard. So, We need to type the numbers from the keyboard when the console is waiting for the user input.

The below program is implemented using Scanner class. Here, calling nextInt() method to take the input from the keyboard. Whatever is pressed on keyboard will be sent to the Scanner and parsed the contents. Finally, input will be stored in variables such as input1 and input2.

package com.javaprogramto.engineering.programs;

import java.util.Scanner;

public class SumOfTwoNumbersScanner {

 public static void main(String[] args) {

  // reading input from user
  Scanner scanner = new Scanner(System.in);
  System.out.print("Enter First Number : ");
  int input1 = scanner.nextInt();
  System.out.print("Enter Second Number : ");
  int input2 = scanner.nextInt();

  // summing two numbers
  int output = input1 + input2;

  System.out.println("Scanner example to Sum of two numbers (" + input1 + ", " + input2 + ") = " + output);

 }

}

Output:

Enter First Number : 100
Enter Second Number : 500
Scanner example to Sum of two numbers (100, 500) = 600

4. String is provided to the nextInt() method. What is output now?

Usually, when an alphabetic or any special charter is inputted from the keyboard, Scanner tries to scan through the regular expression and convert it into int when nextInt() method is invoked. If we pass "100first" as an input then it knows expected integers but received alphabet. So, it will throw runtime exception as below saying java.util.InputMismatchException.

Enter First Number : 100first
Exception in thread "main" java.util.InputMismatchException
 at java.util.Scanner.throwFor(Scanner.java:864)
 at java.util.Scanner.next(Scanner.java:1485)
 at java.util.Scanner.nextInt(Scanner.java:2117)
 at java.util.Scanner.nextInt(Scanner.java:2076)
 at com.javaprogramto.engineering.programs.SumOfTwoNumbersScanner.main(SumOfTwoNumbersScanner.java:12)

The above is the common error when we pass other than numbers.

5. Conclusion

In this article, You have learned how to write a java program to add two numbers in java.

And also seen how to read two numbers from user input and find the sum of them. What are the common errors that we do face during runtime?

Next tutorial, You'll learn how to add two numbers without using '+' operator in java?