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What is Java and Kotlin?

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 Microservices with 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

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, and programmers start searching for various queries like:
  • Kotlin or Java for Android?
  • Kotlin vs Java for Android Development?
  • Which is better Kotlin or Java for Android Development?
  • Which language is best for Android App Development Java or Kotlin?

And the list goes on. In order to resolve Kotlin vs Java issues and give you a clear vision, we have decided to come up with this write-up. Here we will discuss which is best Kotlin vs Java Android Development. So, let’s get started!

Kotlin vs Java - Feature Showdown With Syntax

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.

Parameter Java Kotlin
Compilation Bytecodes Virtual Machine
Null Safety Χ
Lambda Expression Χ
Invariant Array Χ
Non-private Fields Χ
Smart Casts Χ
Static Members Χ
Wildcard Types Χ
Singletons Objects

Java remove boilerplate code and make code highly expressive, and intuitive—easy to both write and maintain. Souce: Java Makes Code Super Expressive

What are the Benefits of Java and kotlin ?

Listed below are the benefits of the Java
  • Java is multiplatform and works on practically any device, server, or operating system
  • Its coding is robust, and it is impossible for Java instruction to corrupt memory or compromise data from other applications of OS X
  • Java is object-oriented and makes it easy to create modular applications and reuse the parts that contribute to the robustness
  • It is ready to use, and with Java, you will get a lot of third-part code ready to use.
  • While comparing Kotlin vs Java performance, to other languages, Java is easy to use, compiling and makes debugging and deploying even simpler
Java is an open-source language that ensures safety since many of its libraries are managed by trusted companies like Google, Apache, and others.

Listed below are the benefits of the Java
  1. Kotlin Application Deployment is faster to compile, lightweight, and prevents applications from increasing size. 
  2. Any chunk of code written in Kotlin is much smaller compared to Java, as it is less verbose and less code means fewer bugs.
  3. Kotlin compiles the code to a bytecode which can be executed in the JVM. Thus, all the libraries and frameworks made in Java transfer and run in a Kotlin project.
  4. Kotlin script helps to configure projects in Android Studio for auto-completion aids, and it helps to reduce compile-time error detection.
  5. It is safe against NullPointerException (The Billion Dollar Mistake ). 
  6. Kotlin incorporates coroutines, as well as interoperability with Javascript for web development.

What are the Challenges of the Java and Kotlin ?

The below are the challenges of Java
  • The syntax that Java uses can be a little complicated or cumbersome while comparing to other languages - like C + or Python.
  • With Java, it is impossible to access certain content that may be incompatible with the device or equipment being used. 
  • It isn't easy to access the new Java enhancements in mobile development.
  • There are times when Java causes problems with Android API design.
  • Test-Driven Development for Java requires writing more code and carries a much higher risk of programming errors and bugs
Java is a bit slower with respect to other programming languages and takes a lot of system memory
Below are the challenges of Kotlin
  • Kotlin is not so popular, and so the developer community is sparse compared to other well-established languages like Java.
  • Kotlin matches weak patterns, and initial code readability becomes a bit difficult to read and understand at first.
  • It has a small support community as Kotlin is younger than Java. Moreover, it has fewer libraries, blog posts and tutorials.
  • Kotlin has a steep learning curve, and switching teams to Kotlin because of language's concise syntax can be a real challenge.
  • There are very few Kotlin developers available in the market. So, finding an experienced mentor is quite tricky.

What are the Applications of Java and Kotlin?

The applications of Java are:

  • Spotify
  • Twitter
  • Cash App
  • Signal
  • Amaze File Manager
The applications of Kotlin are:
  • Pinterest
  • Trello
  • Evernote
  • Twidere for Twitter
  • Shadowsocks

Read more about Java Continuous Integration in Jenkins

Kotlin vs. Java - Feature Showdown With SyntaxKotlin vs Java Android

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, 11 Higher-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

kotlin vs java which is better?

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.

Java vs Kotlin
Share your business challenges with us, and we will work with you to deliver outstanding digital products. Contact Software Development Experts

What are the Key Features of Kotlin Language?

In the following aspects, Kotlin is a better language than Java for Android programming: Build any Type of Application using Kotlin

1. Kotlin compiles to JVM bytecode or JavaScript

Like Java, Bytecode is the compiled format for Kotlin programs also. Bytecode means Programming code that, once assembled, is run through a virtual machine instead of the computer’s processor. By using this approach, source code can be run on any platform once it has been compiled and run through the virtual machine. Once a Kotlin program has been converted to bytecode, it can be transferred across a network and executed by JVM(Java Virtual Machine).

2. Kotlin can use all existing Java Frameworks and Libraries

Yes, Kotlin programs can indeed use all existing Java frameworks and libraries, even advanced frameworks that rely on annotation processing. The main important thing about the Kotlin language is that it can easily integrate with Maven, Gradle, and other build systems.

3. Kotlin can be learned quickly, and it is approachable

It can be rapidly learned by simply reading the language reference. The syntax is clean and intuitive(easy to use and understand). Between Kotlin vs Java, Kotlin looks a lot like Scala but is more straightforward.

4. Automatic conversion of Java to Kotlin

JetBrains integrated a new feature into IntelliJ which converts Java to Kotlin and saves a considerable amount of time. And it also keeps Summing Things Upus to retype mundane code.

5. Kotlin’s null-safety is great

Now get rid of NullPointerExceptions. This type of system helps us to avoid null pointer exceptions. In Kotlin vs Java, Kotlin the system refuses to compile code that tries to assign or return null. Consider the following example –
val name: String = null // tries to assign null, won’t compile.
fun getName(): String = null // tries to return null, won’t compile.

6. Code reviews are not a problem

Kotlin's primary focus is on readable syntax, so code reSumming Things Upviews are not a problem, they can still be done by those team members who are not familiar with the language.

The Additional Features of Kotlin That No One Will Ever Tell You

Listed below are the features of the Kotlin language:

1. It Requires Less Code

Any chunk of code written in Kotlin is much smaller than that written in Java, as it is less verbose. So, "less code equals less bugs." and less time spent on scheduling and project cost savings.

2. It’s Secure

Kotlin is safe against NullPointerException as all the null situations in the code will be warned at compile time. Users have to explicitly specify to the language that an object can be null, and then check the nullity before using it. Kotlin reduces the chances of data loss and bugs.

3. It’s Easy to Learn

One of the most significant benefits of Kotlin is that a Java developer can understand most of the code without ever having written a line of Kotlin.

4. It’s Fun to Use

Although this is very subjective, Kotlin is very fun to use while we talk about Kotlin vs Java. On the other hand, Java bores users with its limitations, its boilerplate, and users encounter errors frequently due to its design problems.

5. Smart Casts

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

6. Type Inference

Summing Things UpIn Kotlin vs Java performance, there is an excellent thing with Kotlin 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, you can also do that. 

7. Functional Programming

The most important thing is that in Kotlin vs Java 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.
Click to explore Kotlin Application Deployment with Docker and Kubernetes

What are the Business Benefits of Kotlin?

  • Adoption of Kotlin is a shallow risk due to its interoperability with Java.
  • The code review and learning curve of Kotlin are straightforward, and developers can learn it quickly.
  • Between Kotlin vs Java, Kotlin has a strong customer service team with a solid reputation. So, no downtime.
  • Kotlin is the combination of functional and procedural programming.
  • Businesses can use Kotlin for any development, including server-based, client web, or Android.

Does Kotlin Have a Future?

Well, the answer is Yes. Kotlin's impact on the IT sector has increased exponentially over the last few years. In fact, some big web portals like Pinterest, Flipboard, or Basecamp are already using it for being supported by the main frameworks. Recent support provided by Google has been the definitive proof that Kotlin has a bright future, and the ability to stand up to Java.


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.

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