Hello, World! is the first basic program in any programming language. Let’s write the first program in Kotlin programming language.
The “Hello, World!” program in Kotlin –
Open your favorite editor notepad or notepad++ and create a file named firstapp.kt with the following code.
// Kotlin Hello World Program
fun main(args: Array<String>) {
println("Hello, World!")
}
You can compile the program in command line compiler.
$ kotlinc firstapp.kt
Now Run the program to see the output in command line compiler.
$kotlin firstapp.kt Hello, World!
You can run the program in Intellij IDEA as shown in Setting up the environment article.
Details about the “Hello, World!” program –
Line #1:
First line is a comment which is ignored by the compiler. Comments are added in program with the purpose of making the source code easier for readers to understand.
- Single line comment
// single line comment - Mulitple line comment
/* This is multi line comment */
Line #2:
The second line defines the main function
fun main(args: Array<String>) {
// ...
}
The main() function is the entry point of every program. All functions in kotlin start fun keyword followed by the name of function(here main is the name), a list of parameters, an optional return type and the body of the function ( { ……. } ).
In this case, main function contains the argument – an array of strings and return units. Unit type corresponds to void in java means the function does not return any value.
Line #3:
The third line is a statement and it prints “Hello, World!” to standard output of the program.
println("Hello, World!")
Semicolons are optional in Kotlin, like other modern programming languages.
Recommended Posts:
- Hello Geeks! app in Kotlin
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- Kotlin labeled continue
- Introduction to Kotlin
- Kotlin Type Conversion
- Kotlin Exception Handling | try, catch, throw and finally
- Kotlin if-else expression
- Kotlin Environment setup for Command Line
- Kotlin constructor
- Kotlin Environment setup with Intellij IDEA
- Kotlin Nested class and Inner class
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- Kotlin Standard Input/Output
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