What is the Difference Between Kotlin Vs Java?

The major difference between Kotlin and Java is syntax and built-in null safety. Kotlin provides a more concise syntax and built-in null safety, while Java has a more mature ecosystem with extensive libraries and tools.

Here is the comparison table for Android Kotlin and Java performance that you can check to get detailed information about both languages.

Sr. no.	Features	Kotlin	Java
1	Extension Functions	Kotlin allows the programmers to add new functionalities to an existing class. By prefixing the name of a class as well as the name of the function, it is possible to develop extended functions.	If we need to extend the functionality of the remaining class, then it is required to develop a new class and parent class. Unfortunately, extension functions are not available in Java.
2	Null Safety	The variables in Kotlin are non-nullable, meaning they can’t be assigned to null values. In case we try to develop, assign or return null values, the Kotlin code will fail. If you want to print the null value for a variable, the declaration will be as follows: value num: Int?=null	NullPointerExceptions are a common source of frustration for Java programmers. It allows users to assign null to any variable, but when accessing an object reference with a null value, it throws a null pointer exception, which the user must manage.
3	Static Members	In Kotlin, we can use the companion object to create static members of the class. An object declaration inside a class can be marked with the companion keyword.	Available in Java. It is used for memory management mainly. One can apply java static keywords with variables, methods, blocks, and nested classes.
4	String Templates	Yes, there are two types of string literals in Kotlin such as escaped string and raw string. Kotlin string template also supports expression.	Available in Java too, but it doesn’t support expressions like Kotlin.
5	Coroutines Support	Coroutines are known as non-blocking or Asynchronous programming, which is an essential part of app development. It is essential to offer scalable solutions to the user.	The corresponding thread Java will be blocked anytime as we launch a long-running network I/O for CPU-intensive tasks. Java permits the creation and executes numerous threads in the background. However, it becomes difficult to manage the overall operations.
6	Wildcard-types	No, Kotlin doesn’t have any wildcard-types. But it has two other things, including declaration-site variance and type projections.	Available in Java. The wildcard, in general, code means (?) that represents an unknown type. It can be used in different situations.
7	Smart Casts	Yes, this feature is available in Kotlin. It helps the Kotlin compiler to track conditions inside of the expression. If the compiler finds a variable that is not null of type nullable, the compiler allows accessing the variable	No, it is not available in Java. However, to know the types in Java, we can use something like an instance to check the type and then cast it to the right type.
8	Lazy Keyword	Yes, it is available in Kotlin. It mainly decreased startup time that is useful when using Kotlin for app development.	This feature is not available in Java.
9	Operator Overloading	Yes, Kotlin allows users to provide a way to invoke functions. It allows us to do an arithmetic operation, equality checks, or compare whatever object we want through symbols like +, -, /, *, %, <, >.	In Java, operators are tied to particular Java types. For instance, String and numeric types in Java can make use of the + operator for concatenation and addition. Another Java type can’t reuse this operator.
10	Blend of Functional and OOP	Kotlin is the blend of functional and object oriented programming.	Java is based only on OOP (Object Oriented Programming).
11	Language Scripting	Kotlin offers language scripting capabilities to use the language straight into your Gradle build scripts.	Java does not enable programmers to use language scripting capabilities.
12	Lambda Expression	Lambda Expression is supported in Kotlin.	The Lambda Expression is not supported in Java.
13	Data Classes	In the case of the requirement of data holding classes in Kotlin, a class needs to be defined with the proper “data” keyword. Moreover, the compiler will take care of building constructors and handle different fields of getter and setter.	It is important to define constructions, hashcode(), toString(), equals(), and variables to store data.
14	Inference Type	Inference type is known as the type constraint problem, and a type constraint solver can resolve this issue. You don’t have to declare the type of each variable based on the assignment; it will automatically be handled in Kotlin. The explicit specification is also allowed.	Each variable should be specified prior to declaration.

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What is Kotlin?

Kotlin is a modern programming language used for developing a wide range of applications, including Android mobile apps, web applications, server-side applications, and desktop applications. Kotlin is designed to interoperate fully with Java, making it easy to use alongside existing Java codebases.

What are the Offerings of Kotin?

Kotlin’s Offerings	Explanation
Readability	Language features like type inference, data classes, and infix functions help with readability. These characteristics make it possible to write compact code without sacrificing readability.
Pragmatic	As Kotlin is designed for large-scale enterprise software development, pragmatism is essential. JetBrains uses it to create their own IDEs. As a result, Kotlin combines feedback from the industry and addresses difficulties related to large-scale software development.
Safety	By design, safety seeks to prevent common software defects. Several languages feature, such as nullable types (to avoid null pointer errors) and nudge you toward best practices like inheritance design.
Interoperability	Kotlin’s interoperability with Java is a key selling factor and a prerequisite for its mainstream adoption in the JVM. Kotlin and Java can coexist, thanks to interoperability, which allows Kotlin libraries and frameworks to be used in Java. The Java Collections API, for example, is used by the Kotlin standard library to communicate with Java. In the context of Kotlin/JS, it also interacts with JavaScript.

Here are some of the best mobile apps we have built using Kotlin and help our clients to generate high revenue and build brand value.

Electronic Signature App

Our team of expert Android app developers has to build an E-Signature App. This app helps to sign your document digitally which will help you to save your money, time, and most importantly paper.

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Best Applications Developed Using Kotlin

Tinder, Netflix, Airbnb, Pinterest, and Uber are some of the best Kotlin app examples you should check.

To know how Kotlin has helped these apps, let’s check the use case for each popular Kotlin-based mobile app along with the app category, revenue details, and links to download the apps.

Apps	Category	Use Cases	Revenue	Download
Tinder	Social-networking App	Kotlin has helped Tinder in its production environment for concise and clear code architecture.	$1.4 billion	Android – iOS
Netflix	Video-streaming App	With the use of 100% Kotlin, the Netflix Android app has rebuilt the current UI player.	$24.9 billion	Android – iOS
Airbnb	Travel App	Airbnb uses Kotlin in the new Android product framework (MvRx) to offer travelers a better experience.	$3.3 billion	Android – iOS
Pinterest	Social-networking App	Kotlin is the primary programming language for the Pinterest Android app. Migrating from Java to Kotlin has produced better outcomes, as it has reduced the time by building code with speed and efficiency.	$442.6 million	Android – ios
Uber	On-demand App	This on-demand taxi service Android mobile app is built using Kotlin. It offers better internal tools and model management. Also, it offers error-free and faster performance.	$14.1 billion	Android – ios

You might think which language is more useful and what are the unique features of Kotlin that are not available in Java, and why choose Kotlin for Android app projects rather than existing Java code. To answer the common questions of Android developers, we have decided to write about what is Java, Kotlin, and their offerings in detail. Let’s start with understanding Java programming language.

What is Java?

Java is a versatile, object-oriented programming language that can be used to build a wide range of applications, including mobile apps, enterprise software, big data applications, and server-side technologies. It is multi-platform, meaning that code written in Java can be run on different types of devices and operating systems.

What are the Offerings of Java?

There are many reasons why a large number of developers are choosing Java for Android app development. This table contains the noteworthy reasons to use Java.

Java’s Offerings	Explanation
Independent Features	Java contains 83 libraries, and it is relatively easy for a developer to use these libraries. Rather than compiling and optimizing native code on multiple devices, Java allows using the independent features for Android development.
Development Environment	Java technology is equipped with a large set of tools like a compiler, an interpreter, a class file packaging tool, and a documentation generator.
Application Environment	Being a standalone program, Java does not require a browser for the code execution. Java is considered a general-purpose language, so it will run on any machine where the JRE is installed.
Robust Memory Management	The Java programming language is robust because it has strong memory management. Additionally, Java uses the idea of references rather than pointers to avoid security issues.

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PayNow Application

Our team has developed a payment app that helps users to perform transactions instead of generating invoices manually Client is just required to open the link and perform the transaction using the Stripe checkout method.

Juvi – Video App for Children

This is the video app that comes with the kid’s mode. This video monitoring app especially helps parents to check the suitable content for their kids. Juvi app also partnered with YouTube and uses their interface so that kids and parents have multiple video options.

Best Applications Developed Using Java

Apps	Category	Use Cases	Revenue (2020)	Download
Spotify	Music	While developing Spotify, API development became an easier and simple process using Java programming language.	$9 billion	Android – iOS
Twitter	Social Network	Java enables Twitter users to easily work across various devices since	$3.72 billion	Android – iOS
Cash App	Mobile Payment Service	Along with the flexibility, the code of Cash App comes with cutting-edge security, which is essential while performing transactions with bank accounts. Java is secure because it runs inside a sandbox and gets checked using byte-code verifiers and library-level safety.	$1.82 billion	Android – iOS
LinkedIn	Social Network	The server side of the LinkedIn app is handled by Java.	$8 billion	Android – ios

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Kotlin vs Java: Detailed Comparison

Functional Programming Language
Kotlin is known as a functional programming language. As Kotlin is a statistically-typed language, it is easier to read and write. In short, Kotlin’s code is streamlined, and the code of Kotlin is easy to comprehend even for the newbie Android developer. This is because Kotlin has a slick Integrated Development Environment (IDE), and its code almost reads like the English language.
Java, on the other hand, is an object-oriented programming language developed by Sun Microsystems. Initially, Java was known as an OAK. Using Java, you can complete all of the tasks and can perform web development using other languages like BASIC and C++.
Verdict: Kotlin wins because it was introduced to reduce the lines of code and create the overall process easy for the developer.
Checked Exceptions
In Kotlin, checked exceptions are not available. Therefore, Kotlin developers don’t find themselves declaring or catching exceptions.
Java supports checked exceptions; due to that, Java is able to offer robust code and handles errors effectively.
Verdict: Java is clearly winning here because it provides checked exceptions to maintain the robustness of the code.
Readable And Straightforward Code
Kotlin is easy to code compared to Java. The language is easy to comprehend because it is statically typed code. Kotlin decreases the chances of compile-time and runtime errors.
Java is not easy to comprehend for new programmers. Due to that, the code results in more bugs. Even, there are higher chances of getting bugs in Java codes due to its complex coding structure. Also, the code in Java is longer, and it becomes hard to streamline the overall process of coding.
Verdict: Kotlin is the winner. Because Kotlin makes the code human-readable and easy to identify mistakes compared to Java.
Data Classes
By simply inserting the “data” keyword in the class definition, Kotlin makes it easier to design data-holding classes.
In Java, developers must define the fields (or variables) that will be used to hold the data, as well as the function Object() { [native code] }, getter and setter functions for the fields/variables, and other functions like hashCode(), equals(), and function toString() { [native code] }() ().
Verdict: Kotlin wins here because it will be easier to design the data classes compared to Java.

So, to understand the benefits of moving from Java to Kotlin, you can go through the following infographic and identify on your own which language is more useful for your next project. To make it easy, we have also prepared an Android Java vs Kotlin infographic to give you a quick look into comparison.

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Infographic On Difference Between Kotlin and Java in Android

We have explained the difference between Kotlin and Java through this infographic image. We have compared both languages used while android development is based on different features. If you want to know about the kotlin vs java performance, please feel free to check these features and differences, please check the below infographic.

Advantages of Kotlin

Bytecode is the compiled format that is used for the Kotlin programs. It means, once the developer is programming the code and assembling it, it runs through a virtual machine and not through the computer’s processor.
The best advantage of using the Kotlin language is that you can still use all the existing Java libraries and frameworks. Moreover, the advanced frameworks as well that rely on annotation processing. The plus point of Kotlin is that a developer can easily integrate Kotlin with Maven, Gradle, and other build systems.
With the help of a new feature integrated by JetBrains into IntelliJ, a developer can easily convert Java to Kotlin and save time. Also, you do not have to retype mundane code for Kotlin.
With Kotlin, you do not have to worry about NullPointerExceptions. The system of Kotlin will help us to avoid null pointer exceptions. If we compare Java vs Kotlin, the system of Kotlin easily refuses to compile code that assigns or returns null.

Limitations of Kotlin

Kotlin has the slower compilation performance. It is the main limitation of Kotlin. In some circumstances, Kotlin outperforms Java in terms of compilation speed, but it is often substantially lower.
The programmers who are proficient in Java language also find it difficult to switch to Kotlin. Therefore, it may require additional expense for a company to arrange the training of Kotlin.
While performing incremental builds, Kotlin is quick. However, to develop a clean build for Android apps, Java is the winner.
Kotlin has existed for the past 6 years. More than 8% of developers are using Kotlin. Due to limited resources and the support from the community, developers are finding it difficult to resolve the challenges in the development process.

Advantages of Java

Java is object-oriented and easier to build modular programs and code.
Java is flexible enough to move from one computer system to another. It is a platform-independent language.
Java is a platform-independent language; it includes the WORA (Write Once Run Anywhere) feature.
Java is a multi-threading language. It means the program permits concurrent execution of multiple parts of the program and makes the highest utilization of the CPU.

Limitations of Java

Java might become memory-consuming and result in poor performance even in comparison to C++ or C. The reason is that Java needs to be converted into machine-level code.
Java only focuses on storage rather than data backup.
GUI builders in Java are still not reliable and mature. Well-known frameworks like SWT, JavaFX, JSF are used for developing UI. You may need to invest extra time in researching before selecting the right GUI builder.
Unsigned int, unsigned char is not supported in Java. However, unsigned int and unsigned long APIs are found in Java 8.

The Future of Kotlin Programming Language

Kotlin has been active since the year 2016. Kotlin was developed by JetBrains, a company backed by the established IntelliJ IDEA IDE. Recently in 2021, Kotlin launched its latest version 1.6.0. Kotlin is enhancing the language by stabilizing experimental APIs and fixing bugs.

Therefore, we can say, the future of Kotlin looks bright because the aim of Kotlin is to tackle the limitations of Java. In addition, Kotlin is a user-friendly and productive language, and programmers would always move towards a scalable programming language.

The Future of Java Programming Language

In the 21st century, if a developer is looking to build an enterprise solution, Java is considered the market leader. As of 2021, Java is used by more than 35.35% of developers. If not Java, one of the JVM languages like COBOL will certainly take its place. Even the tech giants like Google, Amazon, and Microsoft still use Java to streamline their software development process.

Are you still confused about whether to pick Kotlin or Java for building an Android app?

To clear your doubts we have crafted a PDF with 5 reasons why Kotlin should be favored in comparison to Java for Android app development. Download the PDF below and find out what those reasons are.

5 Reasons

Why Kotlin is Better than Java for Android App Development

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Kotlin vs Java: A Quick Roundup Table

Prior to moving to Kotlin or Java, check the below table, which is divided based on the different parameters of Kotlin and Java.

Parameters	Kotlin	Java
Wildcard Types
Singletons Objects
Compilation	Bytecodes	Virtual Machine
Null Safety
Lambda Expression
Smart Casts
Invariant Array

Now you know the difference between Java and Kotlin, based on different features, but which one is a better option? Want to find out? Read the next section.

Kotlin vs Java: Which is Better?

Kotlin is a new programming language and statically typed programming language developed by JetBrains. It is a great fit for developing server-side applications, enabling users to write concise code than Java, allowing app developers to solve the same problems with fewer lines of code.

Kotlin enhances code maintainability and readability that means engineers can write, read, and change code more efficiently.

Looking at the benefits of Java vs Kotlin, developers can easily use Kotlin for anything where Java is used today, including server, client, web apps, and also for developing Android applications. Looking at the benefits of Kotlin, there are some of the other reasons to switch to Kotlin from Java:

Smarter and Safer Compiler
Less code
Easier to Maintain
Boost Productivity
Safer Code
Eliminating Null References
Data Classes
Type Inference

We have also mentioned some of the best advantages of using the Kotlin programming language. Check those benefits in the next section of this blog.

Do you still have some queries? Want to know whether Kotlin is better than Java or it is the same as Java, and many other questions that our reader frequently asked, then read our next section. Find all the questions one-by-one:

FAQs about Kotlin vs Java

Is Kotlin better than Java?
When it comes to comparing Java vs Kotlin and selecting the one which is better, then go for Kotlin because of Kotlin’s documentation; Kotlin code is implemented in a much easier form. In fact, we can say that Kotlin is much better than Java code in terms of security, compatibility, type inference, syntax, data classes, boilerplate code, and functional programming. At the same time, there are features similar on both Java and Kotlin, like lambda expressions, type system, and annotation processing.
Is Kotlin the same as Java?
No, Kotlin is not the same as Java in various points such as speed and performance. Java is a faster programming language than Kotlin. As one test revealed that Java has ~13% faster compilation speeds (with Gradle) than Kotlin (14.2 seconds vs 16.6 seconds) on average. However, the difference in speed is only for full builds.
Should I learn Java before Kotlin?
If you are completely new to the developer community and programming languages, then yes, you should first learn Java code because Android code is still written in Java. Java is an object-oriented programming language. After understanding the basics of Java, you can go with Kotlin code. In case you are an experienced developer, you can start with Kotlin’s course that teaches everything that you need to know about it.
What is Kotlin good for?
Kotlin is good for a lot of things like null safety, unchecked exceptions, property access, smart casts, and lazy loading. There are many other smart features of Kotlin that make it a good programming language.
Is Kotlin good for web development?
Yes, of course. Kotlin can be easily used for more than just Android. You can utilize Kotlin language for back-end systems in place of Java. In fact, you can use Kotlin for front-end development in place of JavaScript. In short, Kotlin is a full-stack solution that can be used on the server, in the web browser, and on mobile.

Ready to Develop Your Mobile App Using Kotlin or Java?

Herein we discussed and compared the major points of Java and Kotlin languages, explained why Kotlin over Java, and gave answers to some of the common questions related to Kotlin. We hope that this comparison helps you to understand the difference and decide which language is more preferable for you as an Android developer.

In any case, if you still have any confusion about whether to use Kotlin or Java for Android application development, what are the benefits of choosing Kotlin over Java, how to hire developers with expertise in Kotlin and Android Studio, get in touch with us through our contact us form. One of our Android or Kotlin app consultants will comprehend your app development project and suggest the right language to choose from.