Kotlin and Its KeyFeatures

Kotlin is a statically typed programming language that runs on the Java Virtual Machine (JVM) and It can also be compiled into JavaScript. It was developed by JetBrains and officially supported by Google for Android development. Kotlin is designed to be fully interoperable with Java, which means that existing Java code can be mixed with Kotlin seamlessly. Here are some key features of Kotlin compared to Java:

Null Safety

Kotlin has built-in null safety features, which means it reduces the probability of null pointer exceptions. Nullable and non-nullable types are explicitly declared, and the compiler helps catch null-related errors at compile-time.
To assign a null value, the programmer must use the dollar sign ($) when declaring a variable; otherwise, an error will be encountered.

Smart Casts

Kotlin has smart casts. Smart cast is an automatic casting mechanism in Kotlin that enables the use of specific variable types without the need for explicit casting following a successful type check.. i.e. In the example below, the variable ‘value’ is of type Any..

fun processString(value: Any) {
    if (value is String) {
        // Within this block, 'value' is automatically cast to String
        println(value.length) // No need for explicit casting
    }
    // Outside the block, 'value' is still of type Any
}

In the example above, after the is String check, within the scope of the if block, Kotlin understands that value is a String, so you can directly access String-specific properties or functions without explicitly casting it. This feature enhances both the safety and readability of the code.

Extension Functions

Kotlin allows the addition of new functions to existing classes without inheritance through extension functions. This promotes a more expressive and clean syntax. It allows you to add new functionality to existing classes without modifying their source code.

Data Classes

Data classes are concise classes used for holding data, Getters and setters are no longer required; you can directly access data values using the variable’s name in data classes. Presented below is an example of a data class,

data class class_name(var1: Int, var2: String, var3: Long)

You can access the variables of the aforementioned data class and modify them using the following syntax:

class_object.var1 = 0
//and
value = class_object.var2

Java Interoperability:

Kotlin is designed to be 100% interoperable with Java. This means that Kotlin code can call Java code seamlessly, and vice versa. It eases the transition for developers already familiar with Java.

Asynchronous Programming(Coroutines):

Kotlin has built-in support for coroutines, which simplifies asynchronous programming. Coroutines make it easier to write asynchronous code in a sequential style, improving readability and maintainability. It completely replaces the AsyncTask method.

Type Inference

Kotlin employs a robust static typing system with type inference, eliminating the need for explicit variable type declarations in numerous cases.

Default Arguments

Kotlin allows function parameters to have default values, reducing the need for method overloads. You have the flexibility to assign default values to function arguments. Here’s an illustrative example of using default arguments.

fun addUser(firstName: String = "Suresh", lastName: String = "Yadav") {
    println("$firstName $LastName")
}

// Example usages
addUser()                       // Outputs: Suresh Yadav
addUser(firstName = "John")          // Outputs: John Yadav
addUser(lastName = "Sinha")        // Outputs: Suresh Sinha
addUser(firstName = "Bill", lastName = "Gates") // Outputs: Bill Gates

Named Parameters

You can call functions with named parameters, making code more readable and allowing for flexible argument order. It allows you to specify the name of the parameter along with its value when calling a function. If you’re dealing with multiple arguments and can’t recall their order, you can easily assign values to parameters by specifying their names. Here’s an illustrative example of using Named Parameters

fun displayUser(firstName: String, lastName: String) {
    println("Name: $firstName $lastName")
}

// Using named parameters
displayUser(firstName = "Anil", lastName = "Kapoor")

Properties and Backing Fields

Kotlin simplifies the creation of getters and setters with concise property syntax. It automatically generates backing fields when needed.

Range Expressions:

Kotlin has a more expressive syntax for defining ranges, making it concise and readable.

Official Android Support

Kotlin is endorsed by Google as an official language for Android development. Many Android developers have embraced Kotlin for its modern features and improved developer experience.