Kotlin vs Java: Which is the Better Option for Android App Development?

Kotlin vs Java: Which is the Better Option for Android App Development?

Developing an Android app is a popular choice for businesses looking to create their own mobile solution. Android, with over 2.5 billion active users spanning over 190 countries, is the most widely used smartphone operating system worldwide.

While many developers choose Android, the debate continues as to whether to build apps using Java or Kotlin. Both programming languages are great options for building high-performing, effective, and feature-packed Android apps.

Comparison of Kotlin and Java

Java was the preferred programming language for building Android apps. Android developers still prefer Java because of its simplicity, portability, platform independence, easy-to-learn nature, and extensive library of resources.

In 2011, JetBrains company created an alternative to Java, Kotlin. JetBrains considered Java’s advantages and disadvantages, along with the best aspects of other programming languages, such as TypeScript, Pascal, Scala, C++, C#, Rust, and JavaScript. By 2019, Kotlin had developed into a robust and stable programming language, and Google claimed it to be a preferred option for Android development.

Why has Kotlin become Google’s choice, and is it still worthwhile to develop Android apps in Java? To answer this question, let’s compare Java and Kotlin using various parameters.

Java and Kotlin Key Features

Java’s main advantage is that it is platform-independent, which means it can run on any device that supports the JVM (Java Virtual Machine). Java is highly secure due to the use of a public key, encryption-based authentication, and its own illegal code-checking system.

With Java, software developers can identify code errors during compilation time and eliminate error-prone states. Java has an extensive set of ready-made solutions and frameworks for faster development and issue solving.

One of the main reasons to choose Kotlin for Android development is that it shortens code length by up to 20% in comparison to Java. This makes Kotlin-based apps more efficient and less prone to bugs.

Kotlin is a versatile programming language that can operate on any platform because it is compiled in bytecode and runs on the JVM just like Java. Due to the use of the JVM, Kotlin can be easily executed in Java, and vice versa. This way, software developers can add as much Kotlin to Java and as much Java to Kotlin as they want, and the developed app will run perfectly.

Ease of use

When it comes to ease of use, Java is a popular programming language that many developers begin their coding journey with due to its simple and straightforward learning curve. However, its code can sometimes be challenging to read. On the other hand, Kotlin may require more effort to learn initially, but once developers become familiar with it, it is generally easier for others to comprehend.

To illustrate this point, let’s examine a “Hello World!” program written in both Java and Kotlin.

Executing the program in Kotlin only took two lines, while in Java it required five lines to accomplish the same task.


When running applications in Kotlin or Java, the code is compiled into bytecode, which is then executed on the JVM. Therefore, comparing how the two languages use memory is quite challenging as they are quite similar in this regard. However, Kotlin offers more features that make it a more functional programming language than Java. As a result, Kotlin’s compilation may take slightly longer than Java’s due to the increased number of features. Nonetheless, the difference in speed is negligible, and it will not affect the performance of business software.


Kotlin and Java easily interoperate with each other, enabling companies to use both programming languages while developing their projects. However, Kotlin takes it one step further by being easily compatible with Apple’s Objective-C and Swift languages. This compatibility allows developers to use Objective-C/Swift frameworks and libraries in Kotlin code, and Kotlin modules can also be used in Objective-C/Swift code.


Kotlin is growing quickly in popularity, especially among young companies building mobile solutions from scratch. However, Java still remains a popular choice for mobile app development, with many companies using it for many years. Moreover, developers who want to work with Kotlin successfully must be well-versed in Java since some libraries used in Kotlin are only compatible with Java. Additionally, Kotlin documentation often refers to Java as a basis for understanding the language.

Community Support

Although Kotlin is a relatively new programming language, it already has well-developed documentation. However, detailed tutorials for Java are still easier to find since Java has been around for a longer period of time. Despite this, Kotlin’s growing popularity indicates that more developers are opting for Kotlin and contributing to its development.

Here are the Key Differences Between Java and Kotlin:

Java and Kotlin have their own distinct features that make them unique. Although Kotlin may not replace Java anytime soon, there are several reasons why developers prefer Kotlin over Java in mobile app development projects.

  • Null Safety:

In Java, NullPointerExceptions can be a major headache for developers when a null value is assigned to variables and objects by default. This opens up an exception, and developers have to handle it. However, in Kotlin, variables and objects do not receive null values by default. If a developer needs to assign a null value, they need to add a question mark to the variable.

  • Extension Functions:

Kotlin allows developers to extend the functionality of existing classes without using inheritance or the decorator design pattern. This makes code less repetitive and reduces the number of classes necessary for app building. In Java, the inheritance function isn’t available, and developers need to write a method first before calling it to perform the needed action.

  • Coroutines Support:

In Java, developers use the multithreading feature to prevent heavy app processes from loading up a smartphone’s CPU and blocking task execution. This increases execution complexity and can result in code errors. Kotlin offers coroutines as an enhanced way to manage multiple threads that simplifies asynchronous code execution. Coroutines are much lighter than threads and allow developers to suspend code execution and resume it later.

  • Data Classes:

In Kotlin, developers can create classes for data storage in just a few clicks by including the keyword “data” in the class definition. The compiler will do the rest of the work. In Java, developers need to write a lot of standard code to create these classes.

  • Functional Programming and Object-Oriented Programming:

Kotlin supports both object-oriented and functional programming constructs, making it versatile for developers used to working in either paradigm. In Java, the introduction of lambda expressions and functional interfaces in Java 8 was an attempt to reduce the amount of code and make it more concise, but it still can’t beat Kotlin in this task.

Advantages of Choosing Kotlin Over Java:

Kotlin’s syntax is not only clean but also easy to understand. Furthermore, Kotlin supports all the Java frameworks and libraries, which ensures fewer iterations, timely releases, and no delays in the development process.

As an open-source language, Kotlin is fully backed by Google, which ensures that the developed Android applications will function seamlessly on any Android device without any exceptions.

In addition, Kotlin performs exceptionally well in benchmarks, with no noticeable delays for end-users. This results in faster and smoother applications with fewer errors.

Kotlin vs Java Which is Better?

While Java remains the preferred programming language for Android development, there are certain scenarios where Kotlin may be a more suitable option. Specifically, industries such as traditional banking and modern fintech companies tend to prefer Kotlin for its reliability and security. By using Kotlin, they can streamline the development process, expedite time-to-market, and create more efficient apps.


While there may be ongoing discussions among mobile developers regarding the superiority of Kotlin versus Java for app development, some have found success utilizing both languages in their projects. By combining Java’s extensive libraries, tools, and JVM with Kotlin’s concise and feature-rich capabilities, even companies that have long relied on Java for their mobile solutions can reap the benefits of Kotlin.

getyoteam’s experienced team stays up-to-date with the latest technological advancements and offers mobile app development using Kotlin as well as efficient migration to Kotlin on Android. Don’t hesitate to contact us for further information or to make a request.

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