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Kotlin Video Series – Functions (Part 1)
This is the seventh part of the video series on Kotlin language.
Read and watch the other parts here.
| 1. | Hello Kotlin |
| 2. | Declaring Variables |
| 3. | Data Types |
| 4. | String (Part 1) |
| 5. | String (Part 1) |
| 6. | Conditional Expressions |
We discuss writing functions in Kotlin language.
We’ve been writing a main function in all these examples. So that should have already given us some idea about the syntax of the functions. A Function is written using the fun keyword.
fun main(args:Array<String>){
println(sayHello("Sam"))
}
fun sayHello(name:String):String{
return "Hello $name"
}
You can omit the return type of a function if doesn’t return anything.
fun print(message:String){
println(message)
}
We can also make a function that does not return anything to return Unit, which means Nothing. Unit can be used in Generics, which we will discuss later.
fun printAgain(message:String):Unit{
println(message)
}
Functions can be written as expressions, like our if-else and when-else constructs. An add function thats adds two numbers can be written as an expression like this.
//Normal function
fun add(x:Int,y:Int):Int{
return x + y
}
//Expressions
fun add(x:Int,y:Int) = x + y
fun square(x:Int) = x * x
}
You can find the video here.
Kotlin Video Series – Conditional Expressions
This is the sixth part of the video series on Kotlin language.
Read and watch the other parts here.
| 1. | Hello Kotlin |
| 2. | Declaring Variables |
| 3. | Data Types |
| 4. | String (Part 1) |
| 5. | String (Part 2) |
In this video, we discuss conditional expressions. Yes, it’s conditional expressions and not just conditional statements.
Let’s write a pretty simple if-else condition.
fun main(args:Array<String>){
val comment:String
if(age > 50)
comment = "Getting old"
else
comment = "You'll get there"
println(comment)
}
if-else conditions can be written as expressions in Kotlin. And that, eliminates the need for having a ternary operator.
//if-else used as an Expression
val anotherComment = if(age > 50){
"Getting Old"
}
else{
"You'll get there"
}
println(anotherComment)
//Even better
val finalComment = if(age > 50) "Getting Old" else "You'll get there"
println(finalComment)
The finalComment variable above just resembles our ternary operator. It’s pretty cool.
switch-case statements are available as when statements in Kotlin.
val age = 52
val comment:String
when(age) {
50 -> comment = "Half century"
25 -> comment = "Young"
else -> comment = "Hmm"
}
println(comment)
val anotherComment:String
when {
age > 50 -> anotherComment = "Getting old"
else -> anotherComment = "You'll get there"
}
println(anotherComment)
The when statements can also be written as expressions like this.
//As an expression
val finalComment = when {
age > 50 -> "Getting Old"
else -> "You'll get there"
}
println(finalComment)
You can find the video here.
Kotlin Video Series – String (Part 2)
This is the fifth part of the video series on Kotlin language.
Read and watch the other parts here.
| 1. | Hello Kotlin |
| 2. | Declaring Variables |
| 3. | Data Types |
| 4. | String (Part 1) |
In this video, we discuss string comparison and string templates.
String comparison is a breeze in Kotlin. We can use == to compare two string literals.
fun main(args:Array<String>){
var lang1 = "java"
var lang2 = "Java"
println(lang1 == lang2)
}
Strings can be compared using the .compareTo method too, which gives you an option to compare the values ignoring the case, like this.
println(lang1.compareTo(lang2,true) == 0)
String templates allow you to embed values in a string using ${expression}
var comments = "$lang1 is cool"
println(comments)
comments = "${lang2} is cool"
println(comments)
You can find the video here.