## Introduction to Integer Variables: Android Studio Crash Course (Free Tutorial)

Have you ever needed to represent a number when coding your application? Well, you’re in the right place! Integers are one of the most common ways to represent numbers, no matter the coding language. Today we’re discussing initializing and declaring integers in Android Studio.

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To follow along with this example in Android Studio, go into Project view. Then go to app > java > (topmost) com.example.zebra.demo > MainActivity.

Integers are whole numbers (not containing decimal places). They can take negative or positive values. Today we’ll be looking at three datatypes used to declare and initialize integers:

1. The most common method is through the use of the keyword `int`. Beneath `setContentView(R.layout.activity_main);`, let’s use this keyword to declare integers named numbers1, 2, and 3. For this example, we’ll assign `number1` and `number2` the values `0` and `9`:

``int number1 = 0, number2 = 9, number3;``

You can also do operations, such as addition, with integers. On a new line, make `number3` equal to `number1 + number2`.

``number3 = number1 + number 2;``

2. Another way to declare integers is with the `Integer` data type. This data type is used when there is the presence of integer arrays (lists of integers). The `Integer` data type takes more memory from your application than `int`.

Use the keyword `Integer` to declare two integers named `number4` and `number5`. On a line beneath that, make `number4` equal to `number1 + number2`.

````Integer number4, number5;`
`number4 = number1 + number2;````

Evidently, you can mix up the `Integer` and `int` datatypes when coding operations.

3. The `BigInteger` datatype is used for integers that span more than 100 digits. For integers that are within -2 billion and +2 billion, you can use `int` and `Integer` datatypes. Otherwise, you have to use `BigInteger`.

Using the datatype `BigInteger`, let’s declare an integer `number6` and assign it the value `1000000000000`. To do so, use the following format:

``BigInteger number6 = new BigInteger("1000000000000");``

Let’s add some more integers beneath that line by first changing the semi-colon to a comma. Declare two integers `number7` and `number8`. Set `number7` equal to a random value such as `23999999999`:

``number7 = new BigInteger("23999999999"), number8;``

In order to set the value of `number8` equal to the sum of `number6` and `number7`, we have to use a built-in function called `add`. So far, your line should look like this:

``number8 = number6.add();``

We must now pass as a parameter a new `BigInteger` value. You can do this by adding `number7` into the parentheses of the `add` function.

You have just implemented some integers in Android Studio! Because numbers often show up in applications, this is a pretty necessary concept to grasp. If you want to learn even more coding for FREE, check out our 30-minute beginners course here: training.mammothinteractive.com/p/learn-to-code-in-30-minutes

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