Java vs Kotlin

The market for mobile applications is rapidly expanding. Businesses use mobile applications to interact and engage with their customers. 

According to Stastica, “Android maintained its position as the leading mobile operating system worldwide in the fourth quarter of 2022, controlling the mobile OS market with a close to 71.8 percent share, while iOS accounted for around 27.6 percent of the mobile operating system market”. This has led to an increase in the development of Android mobile applications in particular. 

Due to their speed, features, and native support for Android Development, Kotlin, and Java are both very popular choices among developers. 

As per StackOverFlow, Java has 33.4% popularity while Kotlin only has 9.3% 

Contrary to the statistics above, Kotlin is actually the most popular language to create Android apps after 2021. Moreover, The majority of companies want to migrate from Java and cross-platform apps to Kotlin apps. 

Google announced the Kotlin First Approach to Android Development at the 2018 Google IO Development Conference. Meanwhile, Google touted Kotlin as the best language to develop Android applications. 

So, we will discuss Java vs Kotlin, two popular choices for Android application programming languages,  

What Is Java?  

Java is an old, simple, powerful, and dynamic object-oriented programming (OOP) language. Moreover, The objective of using this language is to build and manage Android applications, web apps, server apps, embedded systems, big data, etc.

The Write Once Run Anywhere (WORA) theory functions on the premise that Java works on any platform. The language also creates static members that all instances of the class can share.

Released in 1995 by Sun Microsystems, later acquired by Oracle, most of the features of Java language are available in open source.   

Advantages Of Java

Here are the 4 advantages of Java –

1. Easy to use and read:

It is easy for beginners to learn Java language. Therefore, is easy to read, write, and maintain the code in Java.   

2. Automatic memory allocation:

In Java, memory is divided and assigned to either stack or heap. Additionally, The Java Virtual Machine (JVM) assists in conveniently allocating and retrieving memory through automatic allocation.

3. Supports multithreading:

Java can execute several tasks simultaneously. Multithreading allows users to use the CPU to the fullest and individual threads run independently without having any effect on one another.   

4. Secure language:

By eliminating the usage of explicit pointers, Java enhances security. It offers many security features in addition to frameworks like Spring and Spring Boot, which is also known as Spring Security.  

What Is Kotlin?  

Kotlin was first introduced in 2011 by JetBrains, a software development company, in order to make coding in Java more productive. n 2018, Google declared Kotlin an official programming language and positioned it as a more efficient and readable alternative to Java for mobile development.

Kotlin, a statically typed language, can be compiled into JavaScript to function on both browsers and a Java virtual machine (JVM).

Developers have the flexibility to write code in either Kotlin or Kotlin Native, and they can utilize an Integrated Development Environment (IDE) for Native app development.

For Instance – Netflix, Uber, Twitter, and Pinterest code in Kotlin to develop their Android applications, and others to are planning to migrate.  

Advantages Of Kotlin

 Here are the 5 advantages of Kotlin –

1. Interoperability with Java:

With this feature, developers have the window to add new features or migrate code from Java to Kotlin. Both languages can be used together if needed, in an unrestricted manner, making Kotlin robust and a suitable option for both Android and server-side apps.  

2. Null safe:

Kotlin is null-safe. Moreover, This helps prevent errors resulting from absent types or parameters that are not initialized in a correct manner. However, an important thing to keep in mind is that a type is not being used as the default null value.  

3. Easily maintained:

Developers work with already familiar tools since most of the IEDs available in the market support Kotlin.   

4. Highly reliable:

Since the language has undergone multiple beta and alfa versions before being introduced officially, the interface suffers with minimal bugs and is highly usable on a daily basis.   

5. Concise syntax:

With Kotlin, the complexities of Java are removed and no unnecessary tokens or keywords are used. Besides that, it helps in making the code concise.  

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Differences Between Java vs Kotlin  

Choosing between Java vs Kotlin could be a difficult task. Therefore, the following differences between the two would help you make an informed decision.   

1. Object-oriented  

Java: Java is fundamentally an object-oriented programming language.   

Kotlin: Kotlin supports both object-oriented and functional programming. Moreover, This enables coding in Kotlin to be more concise and expressive, with more enabled features.   

2. Null safety:   

Java: In this programming language, it is possible to assign a null value to any variable, which brings NullPointerExceptions into the picture. This eventually frustrates a developer.   

Kotlin: On the other hand, Kotlin, it is not possible to assign null values to any type of variable/object. If we try to do the same, the code, by default, will not get compiled.   

3. Extension functions:   

Java: In Java, the functionality of the existing class can only be extended through the creation of a new class and inherit the parent class. Moreover, Extension functions are unavailable in Java.   

Kotlin: On the contrary, Koltin, an existing class can be extended with new functionality. This can be achieved by prefixing the name of the class to the name of the new function.  

4. Support through coroutines   

Java: Creating and running multiple background threads is possible in Java, however, managing them is a complex task.   

Kotlin: With the Coroutines solution available in Kotlin, it is easier to create and manage multiple threads to run long-running intensive operations. Additionally, Coroutine support suspends execution at a certain point without blocking threads while executing such operations.  

5. Exceptions  

Java: This programming language has checked exception support which makes developers catch and declare the exception, therefore , making the code robust with the right error handling.  

Kotlin: On the contrary, Kotlin does not have checked exceptions. Therefore, developers do not need to catch and declare exceptions, which sometimes might give disadvantages.   

6. Data classes  

Java: Fields or variables to store data need to be established by developers in Java. Furthermore, developers also need to define the constructor and the getter/setter functions for the fields/variables and some other functions.  

Kotlin: With Kotlin, it is simple to create data classes. Additionally, Developers just need to declare a class with the keyword “data” in the class definition.   

7. Casts

Java: Developers need to check the variable types in Java and cast them according to the operation.  

Kotlin: On the other hand, the Smart casts feature in Kotlin handles all casting checks using the keyword “is-checks”, to automatically look after the redundant casts.    

Comparison parameters Java Kotlin 
Object Oriented Object-Oriented programming language Supports both object-oriented and functional programming 
Null Safe Not available Available 
Extension function Not available. Classes need to be created here.  Already available in Kotlin 
Coroutines Not available. Multiple threads complex to run and manage.  Coroutine support is available.  
Exceptions Has checked exceptions Lacks checked exceptions 
Data classes  Fields or variables to store data need to be established by developers.   Easier to create data classes. Meanwhile, Developers just need to declare a class with the keyword “data” in the class definition 
Smart casts Manual Smart casts available 

Also Read: Kotlin Vs Scala – The Right JVM Language

Java vs Kotlin: Usage And Performance  

Kotlin is relatively easier to learn and use than Java. With a comprehensive collection and availability of tools, IDEs, and tutorials, it is easier to develop a mobile application. The speed of coding in both Java vs Kotlin is more or less similar. While Java has more coding processes than Kotlin that allow developers to spend less time thinking of solutions, the latter has more laconic constructions that allow a developer to type less code.   

Java is a mature language with fewer features, yet excellent performance. Java compiles and executes faster than Kotlin, which due to its extensive features takes a little longer to do the same.   

Kotlin, on the other hand, is more functional than Java. It performs better than Java for Android development due to its uses of immutability and features.    

Kotlin is more scalable than Java. Applications developed through Java can sometimes get bloated and as a result, performance gets affected. This is especially the case on older devices like Android phones. Kotlin, on the other hand, focuses more strongly on scalability in its design, reducing bloating and improving the performance of an application. 

Kotlin is popular among millennials as a result of Google’s introduction of their Kotlin first Approach to Android Development while Gen X still adores Java for its simplicity and widespread use.  

Generation gap
Parameters Java  Kotlin 
Ease of use Relatively hard Easy 
Performance Average High 
Scalability Less More 


In this blog, we understood the key functional and performance-wise differences between Java vs Kotlin. While the former is a robust, universal programming language, that has been around since so many years, the latter is a relatively new and fast-emerging programming language. Reliable android mobile app development companies need to weigh all the pros and cons of each language to build a scalable Android application.   

Java is an easy-to-learn language, with more traditional popularity and a larger community of developers. On the contrary, Kotlin lacks the same level of community support and popularity, yet it comes with several additional features and advantages making more present-day developers use it for coding.   

While Java has become an ideal choice for big data, e-commerce, and enterprise systems, Kotlin is preferred for developing contemporary Android applications.  

 To conclude, Kotlin is a better option for developers because the majority of Google libraries support it.


Q1. Is Kotlin better than Java for Android? 

Developers prefer to develop Android applications using Kotlin – 
Kotlin performs better in cases where applications need to run efficiently and smoothly on old Android phones or when developing apps for photo editing. It offers a more structured and efficient design compared to Java, especially when considering scaling.
Android applications are required to maintain platform independence as well as be cross-compiled for usage on multiple platforms including Android. With Kotlin, these functions are possible. However, with Java, these functions cannot be performed due to its use of bytecode which only compiles code for a specific platform in one go.  

Q2. Can I use Kotlin libraries in Java?

Yes, libraries written in Kotlin can be used in Java. It is also easier to migrate from Java to Kotlin.  
Few websites such as Javainuse can help you convert Kotlin to Java code 

Q3. Is Kotlin the future of Android development?

Absolutely. In just 3 years, Kotlin is now utilized by 7.8% of the industry specialists.  
Java may have a lot of popularity but it’s relatively slower and sometimes cumbersome to write code in Java. Java is deprecating and present-day Android developers are transitioning to Kotlin due to its additional features and better functional performance.

Q4. What is the main difference between Java and Kotlin? 

Java, a programming language, serves as a versatile tool for developing Apps, Web Apps, and Desktop applications. It is an old, simple, powerful, and dynamic object-oriented programming (OOP) language.

On the other hand, Kotlin, another programming language, offers the ability to compile into JavaScript and operate on both browsers and a Java virtual machine (JVM).

Q5. Is it easy to learn Kotlin if you know Java?  

Of course yes. All languages share similar concepts but may have different names. If someone is proficient in one language, they can easily excel in another after thoroughly analyzing the use cases and practicing real-world examples. 

Q6. Is Java deprecated in Android? 

No Java is not deprecated for Android Development. Google continues to complete support for Java for Android development. Moreover, Most Android apps use a mix of Kotlin and Java in their code. 

Q7. Does Google recommend Kotlin for Android development? 
Kotlin is touted as Google’s recommended choice for Android development because it supports speed, maintainability, and performance in contrast to Java, one of the most widely used development options.

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