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Kotlin
Basics of Kotlin programming language
By IncludeHelp Last updated : December 04, 2024
1) Basic data types
As we know, we use variables to store some value in the memory address. Thus a variable must have some data type, in Kotlin we have to use val or var to declare any variable. The main difference between the both is that val is used for the read-only variable (like final keyword in java) and var is used to store normal variables.
| Kotlin |
Java |
| var a=5 |
int a=5; |
| val a=10 |
final int a=10; |
Note: variables declared with val are also known as immutable variables.
| Data types |
Size(in bits) |
| Long |
64 |
| Double |
64 |
| Float |
32 |
| Int |
32 |
| Short |
16 |
| Byte |
8 |
Note: like java we can box number in Kotlin.
var a :Int = 5
2) Explicit Conversion
In Kotlin numbers support following conversion.
- toByte() : Byte
- toShort() : Short
- toInt() : Int
- toLong() : Long
- toFloat() : Float
- toDouble() : Double
- toChar() : Char
Example:
var b : Byte = 1
//var c : Int = b //Error
var c :Int =b.toInt() //explicit conversion
Characters
Character are represented by type Char. They are represented by a single character encloses with single quotes.
Example:
var s = 's'
Boolean
- || - OR / lazy disjunction
- && - AND/ lazy conjunction
- ! - NOT/negation
String literals
var s = "Hello world !"
In Kotlin triple quote can be used with a string which contain no escaping and can contain newlines and other characters.
var str = """
for( c in "free")
print(c)
"""
String Templates
In Kotlin Strings can also contain template Expressions (a piece of code) which can be evaluated and whose result can be concatenated with the String.
We use Dolor Sign ($) to start a String template.
Simple Template
var i=10
print("value of i=$i")
Arbitrary Template
Contains some expressions, we use curly Braces for that
var s= "aman"
print("Length = ${s.length}") // optput : Length = 4