Addition Program in Java

An Addition program in Java is the basic program, which is used to introduce to the beginners. The Addition program in Java simply adds two numbers and display to the output screen.

Addition of Two Numbers in Java without using Scanner

It is a simple Java addition program which adds two numbers and display the results. The values are hardcoded by the programmer.

public class Addition{
 public static void main(String[] args) {

   // declare variables
   int num1, num2, sum;

   // take two numbers
   num1 = 10;
   num2 = 20;

   // calculate sum value
   sum = num1 + num2;

   // display the sum value
   System.out.println("Sum = "+ sum);
 }
}

Output:-

Sum = 30

In this program, we take three variables of the int data type. The variables names are num1, num2, and sum. After declaring the variables, num1 and num2 variables are initialized with 10 and 20 respectively. The variables num1 and num2 hold the value of the input. After initializing the variables, the sum is calculated as num1 + num2. Finally, the sum value is displayed using the println() method of the System class.

Simple Java program to Add Two Numbers

In the previous program, values of numbers are hardcoded. But we can also pass these value dynamically to the program. There are various ways to get input from the user in Java. In the below program we use Scanner class to take input from the user.

To get input from the user first we need to import the Scanner class as below:-
import java.util.Scanner;

After import, we can create an object of Scanner class which will be used to get input from the user as:-
Scanner scan = new Scanner(System.in);

Here, Scanner is a class, the scan is a user-defined identifier and new is a keyword used to create an object. For each type of data type separate method is given.

Data typeMethod
bytenextByte()
shortnextShort()
intnextInt()
longnextLong()
floatnextFloat()
doublenextDouble()

Simple Java program to Add Two Numbers

import java.util.Scanner;
public class Addition{
 public static void main(String[] args) {

   // create Scanner class object
   // to take the input
   Scanner scan = new Scanner(System.in);

   // declare variables
   int number1, number2, sum;


   // take input for first number 
   System.out.print("Enter first number: ");
   number1 = scan.nextInt();

   // take input for second number 
   System.out.print("Enter second number: ");
   number2 = scan.nextInt();

   // calculate the sum
   sum = number1 + number2;

   // display the result
   System.out.println("Sum = " + sum);
 }
}

Output:-

Enter first number: 15
Enter second number: 25
Sum = 40

Enter first number: -50
Enter second number: 75
Sum = 25

In the above program, we take two integer data type as input. We can also take double data type as input, for this purpose simply use nextDouble() method. The above program can be written in different ways. The below program takes floating-point numbers and displays the sum to the output screen.

import java.util.Scanner;
public class Addition{
  public static void main(String[] args) {

    // create Scanner class object 
    // to take input values
    Scanner scan = new Scanner(System.in);

    // declare variables
    double number1, number2, sum;

    // take input values
    System.out.print("Enter two floating-point numbers: ");
    number1 = scan.nextDouble();
    number2 = scan.nextDouble();

    // display result
    System.out.println("Sum = " + (number1 + number2) );
  }
}

Output:-

Enter two floating-point numbers: 12.5 17.5
Sum = 30.0

Enter two floating-point numbers: 25.2 8.1
Sum = 33.3

Addition of Two Numbers in Java Using Method

Using the method we can also calculate the sum of two numbers. Methods are similar to functions in C/C++. it takes parameters and returns a value to the caller method. The below program uses a method add() to calculate the sum of two numbers. The add() method taking two double data type value, calculate sum value and return it the caller method.

import java.util.Scanner;
public class Addition{
  public static void main(String[] args) {

    // create Scanner class object 
    // to take input values
    Scanner scan = new Scanner(System.in);

    // declare variables
    double num1, num2, sum;

    // take input values
    System.out.print("Enter two floating-point numbers: ");
    num1 = scan.nextDouble();
    num2 = scan.nextDouble();
    
    // method call
    sum = add(num1, num2);

    // display result
    System.out.println("Sum = " + sum );
  }

  // method to add two numbers
  private static double add(double n1, double n2) {
    // calculate sum and return it
    return n1 + n2;
  }
}

Sum of Two Numbers Using Command Line arguments in Java

Command line is used to pass the arguments at the run time. Similar like other methods main() is also a method with speciality that every Java program execution starts with main method. The main() method take String array value as input and returns void i.e. nothing.

The passed parameters are in String so, first we need to convert it in actual value and then calculate the sum value.

public class Addition{

  public static void main(String[] args) {

    // declare variables
    int num1, num2, sum;
    
    // convert to int value
    num1 = Integer.parseInt(args[0]);
    num2 = Integer.parseInt(args[1]);
    
    // calculate sum
    sum = num1+ num2;
    
    // display result
    System.out.println("Sum = " + sum );
  }

}

While executing this program, pass the values.

> javac Addition.java
> java Addition 10 20

30

If you don’t pass exactly two arguments then it will throw java.lang.ArrayIndexOutOfBoundsException.

> java Addition 10

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
at Addition.main(Addition.java:10)

We have passed only one value, but our program is calculating sum of two numbers. Since second number is not given so it throws an exception.

Similarly, if the passed value is not a number then JVM can’t convert to a number and throws java.lang.NumberFormatException

> java Addition a b

Exception in thread "main" java.lang.NumberFormatException: For input string: "a"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)

Since a and b are not a number that’s why we got an Exception.

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