Kotlin vs Java – which one is better for Android App development?

Kotlin vs Java – which one is better for Android App development?

The Kotlin mobile app development community is continuing to grow. Back in 2017, Google recognized Kotlin by making it the second official language of Android app development. Since then, the programming language has seen impressive growth in demand in both the developer and enterprise community. With Google declaring that Kotlin is now its favored language for Android app developers, the language is demonstrating to be a pragmatic, modern, and intuitive programming language.

What is Kotlin?

Kotlin is a statically typed programming language for Java Virtual Machine (JVM) and JavaScript. Defined as a general-purpose language, Kotlin proposes functional features to support Java interoperability. The Kotlin project was born out of the ambition for heightened productivity. The goal was to enhance the coding experience in a way that was both practical and effective.

A central focus of Kotlin is to allow mixed-language projects. Kotlin also offers improved syntax, as well as concise expressions and abstractions. Using Kotlin with Java decreases excessive boilerplate code, which is a huge win for Android developers.

Kotlin 2019: Where is the language now?  

Since Google I/O 2017, Kotlin has seen bursting growth in Android development and after entertaining KotlinConf only twice, the conference has become something of an establishment in the developer community.

Approachability on all platforms has always been a fundamental objective for Kotlin, but multi-platform programming is only the basis to a much more innovative outlook: distributing code between all platforms. With the announcement of Kotlin 1.3, improvements to Kotlin/Native are developing the concept of multi-platform availability. Finally, Android developers can use one integrated development environment (IDE) to develop with Kotlin on all platforms. The most current release makes mobile app scalability more available by supporting the invaluable benefit of code reuse, saving time, and effort for more challenging tasks.

Kotlin/Native uses the compiler technology LLMV to compile Kotlin sources into stand-alone binaries for many operating systems and CPU architectures like iOS, Linux, Windows, Mac, and Web assembly.

In 2019, more enterprise directors are migrating to Kotlin or preparing to do so. Mobile products like Pinterest, Twitter, Netflix, Uber, Airbnb, Trello, and Evernote are all shifting to Kotlin for Android applications. While the selection of cross-platform Kotlin development hasn’t been critical, major industry players are taking note of the many benefits Kotlin has to offer.

Is this the end of Java?

There are various opinions from developers.

Java is a popular and well-known programming language with enormous open-source tools and libraries to help developers. With that said, no language is without fault and even Java is subject to complexities that can make a developer’s job tiresome. If anything, Kotlin will offer solutions to common programming headaches and improve the Java ecosystem as a whole.

In two years, Kotlin has become a more stable and appropriate development option for Android Studio. Some developers seem to believe that Kotlin will oust Java for Android development in the coming years. Other specialists see Kotlin and Java coexisting without one exceeding the other.

For most, Kotlin’s strengths outweigh the language’s setbacks. There are definite boundaries within Java that impede Android API design. Kotlin is essentially lightweight, clean and far less verbose, particularly in terms of writing callbacks, data classes, and getters/setters. In other words, Kotlin is explicitly designed to improve existing Java models by offering solutions to API design deficiencies.

Kotlin discusses a number of Java’s weaknesses:


A lot of developers appreciate Kotlin for being concise. This is a quality Java is not known for; however, readability should always take precedence over concision. Yes, the succinct nature of Kotlin simplifies a developer’s job and reduces the risk for error, but Kotlin doesn’t practice concision for concision’s sake. Boilerplate code is a problem to read and leads to more bugs and wasted time trying to identify them.

public class ClearBridge { 
public static double calculate (double a, String op, double b) throws Exception { 
	switch (op) { 
		case "add": 
			return a + b; 
		case "subtract":
			return a - b;
		case "multiply":
			return a * b; 
		case "divide": 
			return a / b;
			throw new Exception();

Above is a simple calculator function written in Java. For illustration, here is the same calculator in Kotlin:

fun calculate (a: Double, op: String, b: Double): Double { 
	when (op) { 
		"add" -> return a + b
		"subtract" -> return a - b
		"multiply" -> return a * b
		"divide" - > return a / b 
		else -> throw Exception()

It may not seem like much, but the Kotlin version of this calculator is written in half the lines of code it took to program the function in Java. Brevity is a critical factor in productivity. Writing large projects becomes more manageable when a developer is given more power for every line of code. An important observation here is Kotlin does not neglect comprehension for the sake of brevity. The syntax is short, readable and still firm.

Kotlin vs Java
Kotlin vs Java

Interoperability is Kotlin’s core mission. From the beginning, the project’s purpose has been to use existing experience and expertise to make every library available to Kotlin programmers. Developers can easily write modules in Kotlin that work flawlessly within existing Java code. By releasing the Bytecode, a Kotlin compiler enables the two languages to work in unison in the very same project.

Inbuilt Null Safety

Kotlin’s type of system has inbuilt null safety. The infamous NullPointerException is mostly responsible for Android development mistakes. Android relies on null to interpret the absence of a value, but null can easily kill an app. Kotlin solves this problem by incorporating natural null safety. This extension saves developers from writing extra code to work around the issue.

No Raw Types

Before generics came into play, raw types were used considerably frequently. Raw types support for backward compatibility, but raw types can throw a CastClassException and the error will happen during execution and not the compiling stage. Kotlin does not allow raw types, and as a result, provides a more type-safe code.

No Checked Exceptions

The checked exception characteristic in Java can be problematical. Checked exceptions are when the compiler forces the caller of a function to catch or (re-throw) an exception. The fact is, checked exceptions are often irrelevant and cause empty catch blocks. Non-existent checked exceptions are irritating for developers because blank catch blocks force developers to weed through the code to identify a nonexistent exception. As a solution, Kotlin removes them completely, which minimizes verbosity and improves type-safety.

Is it Necessary for Developers to Learn Kotlin?

Again, there are different opinions.

While it is not entirely essential for developers to make the switch to Kotlin, they’re going to meet the language eventually. If you’re already familiar with Java, learning Kotlin will be easy. The language is poised to impact app development on an extensive scale, so it doesn’t hurt to learn the basics of the language. Additionally,  arising with modern techniques and development styles will aid the maturity of any developer’s skill set.

The Business Benefits of Switching to Kotlin

Redoing large pieces of a project in a new programming language is a serious determination; however, Kotlin offers two essential business benefits impacting the choice.

Reduced Project Timelines

Kotlin’s brevity advantages mean the language can solve more difficulties with fewer lines of code. Kotlin’s concise nature enables developers to read and modify code more efficiently which can decrease a project’s time-to-market.

Fewer App Crashes

Again, Kotlin products use less lines of code as opposed to Java programs. Not only does less code decrease development time, but fewer lines of code also help maintenance needs. There is less surface area for bugs to hide and the enhanced readability of the language makes locating bugs easier for developers, appearing in fewer crashes and system failures.

Making the Switch from Java to Kotlin

There are two things to keep in mind when choosing if Kotlin is the right choice for your mobile product. First, make sure your product team is ready to make the switch. Including a new language, rewriting and optimizing your project includes a learning curve. It’s important to make sure your team is ready to accommodate any obstacles in the learning process. It is equally important to recognize how the switch will impact your present architecture. Changing programming languages can produce the deletion, creation, and merging of particular artifacts and classes. As a result, your product’s architecture can be corrupted. It’s critical to secure your mobile architecture is expandable and can control the evolution of your product.

The Future of Kotlin

Since the origin of 2018, roughly 1.5 million developers wrote in Kotlin code and midway through 2019, that number has nearly duplicated. With enormous brands starting to use Kotlin, support from JetBrains and Google, and an around global attachment to the programming language, it’s pretty safe to say that Kotlin will be around for a while. The real question is: will Kotlin become the winner “write once and run everywhere” language?

Kotlin is fast proving itself to be a preferred programming language for mobile app development and presents developers with a wealth of possibility to experiment with advanced programming. Overall, Kotlin is establishing a new standard for what a programming language should be able to achieve.

But, can you yet answer the “Kotlin vs Java – which one is better for Android App development?” question yet?

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