Introduction
Understanding data types is fundamental to effective programming. In Kotlin, data types specify the kind of values that variables can hold. Kotlin is a statically-typed language, which means that the type of a variable is known at compile time. This chapter will cover the basic data types in Kotlin, including examples and syntax for each type.
Basic Data Types
1. Numeric Types
Integer Types
Kotlin provides several types for whole numbers, each with different ranges.
- Byte: 8-bit signed integer.
- Short: 16-bit signed integer.
- Int: 32-bit signed integer.
- Long: 64-bit signed integer.
Syntax:
val variableName: DataType = value
Example:
fun main() {
val byteValue: Byte = 10
val shortValue: Short = 20
val intValue: Int = 100
val longValue: Long = 1000L
println(byteValue)
println(shortValue)
println(intValue)
println(longValue)
}
Floating-Point Types
Kotlin provides types for decimal numbers.
- Float: 32-bit floating-point number.
- Double: 64-bit floating-point number.
Syntax:
val variableName: DataType = value
Example:
fun main() {
val floatValue: Float = 10.5F
val doubleValue: Double = 20.5
println(floatValue)
println(doubleValue)
}
2. Boolean Type
The Boolean type represents true/false values.
Syntax:
val variableName: Boolean = value
Example:
fun main() {
val isKotlinFun: Boolean = true
val isJavaOld: Boolean = false
println(isKotlinFun)
println(isJavaOld)
}
3. Character Type
The Character type represents a single character.
Syntax:
val variableName: Char = 'value'
Example:
fun main() {
val letter: Char = 'K'
println(letter)
}
4. String Type
The String type represents a sequence of characters.
Syntax:
val variableName: String = "value"
Example:
fun main() {
val greeting: String = "Hello, Kotlin!"
println(greeting)
}
Type Inference
Kotlin can infer the type of a variable based on the value assigned to it, which means you don’t always have to explicitly declare the type.
Syntax:
val variableName = value
var variableName = value
Example:
fun main() {
val number = 10 // Int
val pi = 3.14 // Double
val greeting = "Hello, Kotlin!" // String
val isFun = true // Boolean
println(number)
println(pi)
println(greeting)
println(isFun)
}
Arrays
Arrays are used to store multiple values of the same type.
Syntax:
val arrayName = arrayOf(value1, value2, value3)
Example:
fun main() {
val numbers = arrayOf(1, 2, 3, 4, 5)
println(numbers[0]) // Output: 1
numbers[0] = 10
println(numbers[0]) // Output: 10
}
Conclusion
In this chapter, you learned about the basic data types in Kotlin, including numeric types, boolean, character, string, and arrays. Understanding these data types is essential for writing effective Kotlin programs, as they define the kind of data you can work with and how you can manipulate it.