How to Add Two Numbers in Java

# How to Add Two Numbers in Java

clickHere
Updated on Mar 13, 2024 14:23 IST

The addition is the fundamental aspect we use to learn programming in any language. In this article, we will learn different methods to add two numbers in java. So, without further delay let’s dive deep to learn how to add numbers.

In our earlier education days, we must learn addition, subtraction, division, and multiplication. We use the ‘+’ operator to add two integers. Similarly, we use the ‘+’ operator to add two numbers in Java. We say operands to these numbers because we do operations on operands. When we add two numbers, always remember that the size of the result should not extend the size of the data type.
Addition uses ‘+’ operator on two numbers

## a + b

Here, a and b are two operands.

Must Check: Variables in Java

Let’s look at the different ways by which we can add two numbers in Java.

### Addition of two numbers using ‘+’ operator

In the below code, we take two integers a =10 and b =20 and add these two numbers using ‘+’ operator and store the result in sum which is the integer type.

Code:

`public class Main{ public static void main(String args[]) { int a = 10; int b = 20; int sum = a + b; System.out.println("Addition of a and b is:"+ sum); }}Copy code`

Output

Must Check: Java Online Courses and Certification

### Addition of two numbers in Java with User input

In the below code, we use nextInt() method of Scanner class to take input from user.

Code

```import java.util.Scanner; public class Main{ public static void main(String args[]) { Scanner sc=new Scanner(System.in); System.out.println("Enter a first number:"); int a = sc.nextInt(); System.out.println("Enter a second number:"); int b = sc.nextInt(); int sum = a + b; System.out.println("Addition of a and b is:"+ sum); }}Copy code```

Output:

Must Read: Understanding Java Scanner Class

### The sum of two numbers in Java using a method

#### By using sum() method

Integer class in Java has a method sum(), which we use two add two numbers by passing arguments in the sum() method. Observe the code for better understanding.

Code:

```import java.util.Scanner; public class Main{ public static void main(String args[]) { Scanner sc=new Scanner(System.in); System.out.println("Enter a first number:"); // Taking input of integer int a = sc.nextInt(); System.out.println("Enter a second number:"); // Taking input of integer int b = sc.nextInt(); // calling sum method by passing integer a and b int sum = Integer.sum(a, b); System.out.println("Addition of a and b is:"+ sum); }}Copy code```

Output:

#### By using a user-defined method

In the below code, we make a static method sum that takes two integers as arguments and has return type int. This method adds two integers passed as arguments and returns the result. Observe the code.

Code:

```import java.util.Scanner; public class Main{ public static int sum( int a, int b) { int ans=a+b; return ans; } public static void main(String args[]) { Scanner sc=new Scanner(System.in); System.out.println("Enter a first number:"); // Taking input of integer int a = sc.nextInt(); System.out.println("Enter a second number:"); // Taking input from integer int b = sc.nextInt(); // calling sum method int sum = Main.sum(a, b); System.out.println("Addition of a and b is:"+ sum); }}Copy code```

Output:

### By using for loop

We can add numbers using for loop. In the below code, we first take input from the user on how many numbers to be added; suppose the user enters n numbers to be added, then we enter into for loop n times and take number input one by one and add the number to sum, which is initialized to zero. After the addition of all the numbers, we will return the sum. Observe the code for better understanding.

Code:

```import java.util.Scanner; public class Main{ public static void main(String args[]) { Scanner sc=new Scanner(System.in); System.out.println("Enter total numbers to be added:"); int n=sc.nextInt(); int sum=0; for(int i=0;i<n;i++) { System.out.println("Enter a number:"); int num=sc.nextInt(); sum+=num; } System.out.println("Sum of numbers:"+ sum); }}Copy code```

Output

Must Read: Mastering For Loop in Java

## Special Case: When Integers are in String Form

Let’s take a case when integers are in String form and how we can add these integers. So, for this type of scenario in Java, we have some inbuilt methods in the Integer class. We can use Integer.parseInt() method to Integer, and then we typecast the Integer to int. Let’s take a program to understand this clearly. For example, we have String a and String b as

String a=”400″;

String b=”100″;

Code:

```public class Main{ public static void main(String args[]) { String a="400"; String b="100"; //we use parseInt() method of Integer to convert a String value to Integer // Converted Integer is type cast into int; int val1=(int)Integer.parseInt(a); int val2=(int)Integer.parseInt(b); int sum=val1+val2; System.out.println("Sum of a and b is:"+sum); }}Copy code```

Output

## Conclusion

In this article, we have discussed different methods to add two numbers in Java with the help of examples.

Hope you will like the article.

Keep Learning!!

Keep Sharing!!

Contributed By: Shubham Kumar