Kotlin Vs. Java

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Kotlin vs Java: The Battle of Programming Languages

Developing Android applications is a great option to drive success to your business but, picking up the best programming language is the real dilemma. For many of us, it is evident that Java is the best as it is everywhere and everyone praises it. However, after the arrival of Kotlin, this apparent belief in Java is somewhat shaken.

What is Java?

Java is the native language used by Android, applications that communicate with the operating system and directly use the hardware uses Java. This language allows the creation of any program and supports almost all types of machines, and OS X be it Android, Windows, or Linux.Java was developed by Sun Microsystems (now the property of Oracle) and one can use Microservice with java.

What is Kotlin?

In Kotlin vs Java, Kotlin is the newly created language that is inspired by Java, but it is an improved version of it with so many additional features. It is clean, relatively simple, and carries fewer formalities and rules compared to Java and other programming languages. In order to use this language to program Android apps, developers still need to understand basic programming concepts and structures.

Kotlin vs Java: A Quick Roundup

Although Kotlin is an officially supported language to write Android Apps, you still may feel that there are not enough reasons to switch. Java has been shown to work for all of these, then why should you change?So, here are the reasons why moving to Kotlin is one of the best things you can do.

CompilationBytecodesVirtual Machine
Null SafetyΧ
Lambda ExpressionΧ
Invariant ArrayΧ
Non-private FieldsΧ
Smart CastsΧ
Static MembersΧ
Wildcard TypesΧ
Singletons Objects

Kotlin vs Java – Feature Showdown With Syntax

1. Null Safety

NullPointerException or NPE is one of the main drawbacks of Java, and the only possible reason for NPE is an explicit call to throw NullPointerException. Some of the data inconsistency related to initialization, or other issues caused by external Java code.As already mentioned in the above section that in Kotlin vs Java, Kotlin avoids NullPointerException. Kotlin fails at compile-time whenever a NullPointerException may be thrown.

2. Data Classes

In Kotlin vs Java Android, Kotlin there are Data Classes that lead to the auto-generation of boilerplate like equals, hashCode, toString, getters/setters, and much more. Consider the following example:/* Java Code */

class Book {
private String title;
private Author author;
public String getTitle() {
return title;
public void setTitle(String title) 
this.title = title;
public Author getAuthor() {
return author;
public void setAuthor(Author author) 
this.author = author;

But in Kotlin the same above class can define concisely in one line –/* kotlin Code */

data class Book(var title: String,
var author: Author)

3. Extension Functions

Kotlin allows us to extend the functionality of existing classes without inheriting from them. Means to say that in Kotlin vs Java, Kotlin provides the ability to develop a class with new functionality without having to inherit from the class. Extension functions do this.To declare an extension function, we need to prefix its name with a receiver type, i.e. the type being extended. The following adds a swap function to MutableList –

fun MutableList < Int > .swap(index1: Int, index2: Int) {
val tmp = this[index1]
this[index1] = this[index2]
this[index2] = tmp

The ‘this’ keyword inside the extension function corresponds to the receiver object, passed before the dot. Now we can call such a function on any MutableList –

val abc = mutableListOf(1, 2, 3)
abc.swap(0, 2)

4. Smart Casts

When it comes to casts, Kotlin’s compiler is intelligent. In many cases, one does not need to use explicit cast operators in Kotlin, but in Kotlin vs Java, Kotlin there is “is-checks” for immutable values, and inserts cast automatically when required –

fun demo(x: Any) {
if (x is String) {
print(x.length) // x is automatically cast to string

5. Type Inference

In Kotlin, there is a great thing that you don’t have to specify the type of each variable explicitly(in clear and detailed manner). But if you want to define a data type explicitly between Kotlin vs Java Android, you can also do that. Consider the following example –/* not explicitly defined */

fun main(args: Array < String > ) {
 val text = 10
/* explicitly defined */
fun main(args: Array < String > ) {
 val text: Int = 10

6. Functional Programming

The main important thing in Kotlin vs Java performance is that Kotlin is a functional programming language. Basically, Kotlin consists of many useful methods, which include higher-order functions, lambda expressions, operator overloading, lazy evaluation, operator overloading and much more. Functional Programing makes Kotlin much handier when it comes to collections –

fun main(args: Array < String > ) {
val numbers = arrayListOf(15, -5, 11, -39)
val nonNegativeNumbers = numbers.filter 
 it >= 0

Output –15, 11Higher-Order Functions are those functions that take functions as a parameter and also returns a function. Consider the following code:-

fun alphaNum(func: () -> Unit) {}

In the above code “func” is the name of the parameter and “ ( ) -> Unit ” is the function type. In this case, we are saying that func will be a function that does not receive any parameter and does not return any value also. Lambda expression or an anonymous function is a “function literal”, i.e. a function that is not declared but passed immediately as an expression. An Example of a Lambda Expression –

val sum: (Int, Int) - > Int = {
 y - > x + y

In the above example, we simply declare a variable ‘sum’ that takes two integers and adds them together and returns total as an integer. Then we just use ‘ sum(2,2) ’ in order to call it. Pretty cool huh?Anonymous Function in Kotlin vs Java Android, is a function that allows us to specify the return type and in this, the function name is omitted. Consider the following example:-Either this way –

fun(x: Int, y: Int): Int = x + y
or This Way
fun(x: Int, y: int): Int {
 return a + b

So, Who Took The Crown?

Kotlin obviously.This is so because Kotlin interworks with Java and provides incremental change of code and superior type system to Java and provides the easy Migration path from Java with backward compatibility.With features like more declarative, less code, mixed language database Kotlin more expressive than Java. In Kotlin vs Java, it makes Kotlin the future language for enterprise applications and Mobile.

Summing Things Up

We know that a clean build is done only one time in our project, and I think Incremental Builds Compilation time is more crucial for us than Clean Build. So in Kotlin vs Java, Kotlin is almost the same as Java, and yes we can go with Kotlin without worrying about Compilation time.