Java is an object-oriented programming language, which has been in practice for more than 20 years. Particularly, since 2014 Java has been officially used in the development of mobile applications based on the most popular in the last 8 years mobile operating system – Android. Despite the fact that this programming language stood the test of time and was trialled by experienced developers, there are new, more convenient alternatives appearing from time to time in the IT sphere, which gradually lower the demand for Java. One of such alternatives is backward compatible with Java, statically typified programming language – Kotlin, created by JetBrains developers’ team as a concise and safer (from the troubleshooting point of view) analogue to Java. Hence the question – “Should I choose Kotlin or Java?”

Java vs Kotlin comparison

Nowadays, Java practicing programmers’ community split into two camps: ones loyal to the mentioned programming language and ones planning to move on to Kotlin. But can it decently replace Java and should you switch to Kotlin in the end? This article’s main goal is to compare Kotlin to Java to help achieve reasonable conclusion.


Why do developers still use Java?

Let us consider general advantages of Java:

• Thorough errors’ detection. Java is supported by the overwhelming majority of IDE. That is the reason why developers are able to choose a tool with the optimal compiler. Furthermore, due to static typing, assignment of values to variables, parameters or return values in functions is performed once, on the stage of their announcement. This way, compiler gives a warning when mistaken value is assigned, which excludes the app’s inappropriate functioning.

• Plenty of experts ready to help. Java is quite an “adult” programming language, which means that the developer can answer the question “how to implement one or another function in code?” via internet search (e.g. having found the solution on themed forums or educational resources).

•C-orientation. The developing language in discussion resembles C programming language a lot, so the transition from Java will be smooth for those, who have practiced C or similar languages before.

• Compatibility with a number of libraries. Java is integrated with a significant number of libraries enabling the possibility of increasing its already impressive functionality. Today, most apps have to include the function of immediate messaging. Java-supported library RXJava provides the possibility of development of event algorithms and, particularly, mechanisms of self-guided messages in declarative coding style.

• Clear coding standards. The functionality provided by Java is realized via the predetermined commands, so the novice developers are less confused during the application’s coding.

• Platform’s independence. Being one of the Java’s key components, JVM provides compatibility of the created byte-code with most modern platforms. Therefore, Java is a multi purpose programming language that can be interpreted by most devices.

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Why are some programmers in search of Java alternatives?

As any other programming language, Java has its set of disadvantages. Below are the general ones:

• Narrow OOP framework. Java has limited OOP boundaries and is complicated in implementation of this paradigm’s basic principles.

• Complicated in understanding generics. Having first appeared in JDK 1.5, generics enable the abstraction of a number of types and are one of the main reasons why Java is considered to be among the best developing languages from the functionality point of view. However, novices will need a lot of time and effort to master their specifics.

• Exceptions as frequent sources of errors. Exceptions, and catch blocks in particular can be frequent sources of errors even when the experienced programmers are at work.


Is Kotlin better than Java?

Is Kotlin better than Java in the long run? To answer that, let us consider the main advantages of Kotlin:

• High compilation performance. Compilation speed in partial incremental builds is 5-15% higher than that of Java. Accordingly, performance of the processes coded via Kotlin is also higher. This can be clearly observed in the work of multithread applications, which are characterized by the fast execution (compared to Java-based analogues).

• Concise syntax. Java is often being “scolded” for the complexity in visual perception of some coding constructions. Kotlin is far more advanced in this regard, fitting all the required commands into one line compared to more than ten lines in Java.

• Minimal risk of errors in code. Developers working with Kotlin are less prone to making mistakes that cannot be detected by the compiler due to conciseness of the constructions in development.

• Large number of themed forums. There are a lot of forums dedicated to work with Kotlin in the web, despite the language’s relatively “young age”. The developers can find answers to frequently asked questions and create new themes there.

• Laxity in algorithms development. Despite the fact that both Kotlin and Java are object oriented programming languages, there are strict functional paradigms in Kotlin, which are common in Java. This way, the programmers can choose the most flexible way of the implementation of capabilities.

• No need to use null pointer exceptions. The probability of appearance of bugs related to null references is excluded in Kotlin development. It is enough to remember the One Billion Dollar Mistake story to realize the scale of such faults’ outcome.

• Platform independence. Kotlin developers presented the preview of Kotlin/Native v2.0 technology that provides the code’s compilation without the virtual machine’s aid, in May 2017. This gives the possibility of the development of common libraries for various platforms.

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So, should you switch to Kotlin?

All the mentioned advantages of Kotlin are contraposed to its disadvantages though. General disadvantages of Kotlin are listed below:

•Functional programming style. Not always the absence of specifics in the paradigm (which is common for Java) of the programming language in question results in the positive developing experience. Mastering Kotlin programming skills is difficult when one is used to imperative programming style.

•Complexity in the code interpretation. Even the single-line constructions can delineate the whole algorithm due to utter conciseness of Kotlin. Which means that the pre-developed algorithm is much more complicated in interpretation as opposed to Java.

•Absence of structure description syntax. Structure description in Kotlin is limited by three functions: listOf, mapOf and arrayOf. That is quite discomfortable during the work with more complex than one-dimensional lists data.

•Problems in the use of generics. Kotlin also utilizes generics, however, as in the case of Java, it features quite complex scheme of work with them. This can make the learning process more difficult for novices.

Kotlin or Java: which one is better?

The article’s objective was utterly honest and transparent Java vs. Kotlin comparison. As a result, Kotlin seems to be more progressive and comfortable language for teamwork due to its conciseness and simplicity. You can forget all the doubts and make an optimal choice – Kotlin.

Java vs Kotlin: Basic Review for Android Development
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