In this blog, we’re going to take a look at Kotlin, a new language in the JVM world, and some of its basic features, including classes, inheritance, conditional statements, and looping constructs.
Defining function in kotlin
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fun sum(a: Int, b: Int): Int { return a + b } //Function with an expression body and inferred return type fun sum(a: Int, b: Int)=a+b |
Defining variables
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val a: Int = 1 // immediate assignment val b = 2 // `Int` type is inferred val c: Int // Type required when no initializer is provided c = 3 // deferred assignment |
Using when expression it’s more like switch case.
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when(a){ 1->fun sum(a: Int, b: Int)= a+b 2->fun sub(a: Int, b: Int)=a-b else-> a } |
Using a for loop
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val items = listOf("apple", "banana", "kiwi") for (item in items) { println(item) } // While loop val items = listOf("apple", "banana", "kiwi") var index = 0 while (index < items.size) { println("item at $index is ${items[index]}") index++ } |
Constructors
A class in Kotlin can have a primary constructor and one or more secondary constructors. The primary constructor is part of the class header it goes after the class name (and optional type parameters).
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class Person constructor(firstName: String) { } // Secondary Constructor class Person { constructor(parent: Person) { parent.children.add(this) } } |
Have you notice there no semicolon in sentences in Kotlin you don’t have to put the semicolon at the end of sentences. Null-safety is an important feature of the Kotlin language. It helps developers avoid NullPointerExceptions and improves the quality of their apps.