Data type (basic type) refers to type and size of data associated with variables and functions. Data type is used for declaration of memory location of variable which determines the features of data.
In Kotlin, everything is an object, which means we can call member function and properties on any variable.
Kotlin built in data type are categorized as following different categories:
- Number
- Character
- Boolean
- Array
- String
Number Types
Number types of data are those which hold only number type data variables. It is further categorized into different Integer and Floating point.
| Data Type | Bit Width (Size) | Data Range |
|---|---|---|
| Byte | 8 bit | -128 to 127 |
| Short | 16 bit | -32768 to 32767 |
| Int | 32 bit | -2,147,483,648 to 2,147,483,647 |
| Long | 64 bit | -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807 |
| Float | 32 bit | 1.40129846432481707e-45 to 3.40282346638528860e+38 |
| Double | 64 bit | 4.94065645841246544e-324 to 1.79769313486231570e+308 |
Character (Char) Data Type
Characters are represented using the keyword Char. Char types are declared using single quotes (”).
| Data Type | Bit Width (Size) | Data Range |
|---|---|---|
| Char | 4 bit | -128 to 127 |
Example
val value1 = 'A'
//or
val value2: Char
value2= 'A' Boolean Data Types
Boolean data is represented using the type Boolean. It contains values either true or false.
| Data Type | Bit Width (Size) | Data Value |
|---|---|---|
| Boolean | 1 bit | true or false |
Example
- val flag = true
Array
Arrays in Kotlin are represented by the Array class. Arrays are created using library function arrayOf() and Array() constructor. Array has get (), set() function, size property as well as some other useful member functions.
Creating Array using library function arrayOf()
The arrayOf() function creates array of wrapper types. The item value are passed inside arrayOf() function like arrayOf(1,2,3) which creates an array[1,2,3].
The elements of array are accessed through their index values (array[index]). Array index are start from zero.
val id = arrayOf(1,2,3,4,5)
val firstId = id[0]
val lasted = id[id.size-1] Creating Array using Array() constructor
Creating array using Array() constructor takes two arguments in Array() constructor:
- First argument as a size of array, and
- Second argument as the function, which is used to initialize and return the value of array element given its index.
val asc = Array(5, { i -> i * 2 }) //asc[0,2,4,6,8] String
String in Kotlin is represented by String class. String is immutable, which means we cannot change the elements in String.
String declaration:
val text ="Hello, JavaTpoint" Types of String
String are categorize into two types. These are:
1. Escaped String: Escape String is declared within double quote (” “) and may contain escape characters like ‘\n’, ‘\t’, ‘\b’ etc.
val text1 ="Hello, JavaTpoint"
//or
val text2 ="Hello, JavaTpoint\n"
//or
val text3 ="Hello, \nJavaTpoint" 2. Raw String: Row String is declared within triple quote (“”” “””). It provides facility to declare String in new lines and contain multiple lines. Row String cannot contain any escape character.
val text1 ="""
Welcome
To
JavaTpoint
"""
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