Kotlin vs. Java: All-purpose Uses and Android Apps

It is a fact that Java was defeated in the Android war by Kotlin, which is currently Google's preferred programming language and is consequently better suited to the development of new mobile applications.

However, Kotlin and Java both have many benefits to offer as general-purpose programming languages, and it is essential for developers to have a solid understanding of the distinctions between the two languages, especially if they intend to make a transition from Java to Kotlin. In this post, we will compare and contrast the programming languages Java and Kotlin so that you may make more educated judgements and transition more easily between the two.

Are Kotlin and Java Similar?

In point of fact, the two languages share a great deal of similarities when viewed from a higher level. Kotlin and Java are both interpreted by the Java Virtual Machine, also known as the JVM, rather than being compiled directly to native code. And the two languages are able to effortlessly communicate with one another: Kotlin code can be called from Java, and Java code may be called from Kotlin. Java's versatility makes it applicable to a wide variety of contexts, including server-side programmes, databases, web front-end applications, embedded systems and enterprise applications, smartphones, and more. Kotlin is similarly versatile: In addition to being useful for server-side, web, and desktop development, it is also compatible with the Java Virtual Machine (JVM), Android, JavaScript, and Kotlin/Native.

Java was first made available to the public in 1996, making it a significantly more experienced programming language than Kotlin. Despite the fact that Kotlin 1.0 wasn't released until much later, in 2016, Kotlin rose to prominence quite quickly and is now the official language of choice for Android development as of 2019. However, aside from Android, there is no recommendation to switch from Java to Kotlin as a programming language.

Performance and Memory Usage Comparing Kotlin with Java

Before delving into the specifics of Kotlin and Java's feature sets, let's compare the two programming languages' overall performance and the amount of memory they use, both of which are usually considered to be crucial aspects for both developers and customers.

The performance of Kotlin, Java, and the other languages supported by the JVM, while not identical, is fairly comparable, at least in comparison to the performance of languages supported by other compiler families, such as GCC and Clang. The JVM was first developed in the 1990s with the intention of being used on embedded systems that had a finite amount of resources. The environmental regulations that went along with it led to two major restrictions:

Simple JVM bytecode: The most recent version of JVM, which is used to build both Kotlin and Java, consists of only 205 different instructions. In comparison, a contemporary x64 processor is easily capable of supporting over 6,000 encoded instructions, however the exact number depends on how the instructions are counted.

Runtime (vs compile-time) operations: Runtime optimizations, as opposed to compile-time optimizations, are encouraged by the multiplatform strategy (also known as "Write once and execute anywhere"). To put it another way, the JVM is responsible for the runtime translation of the majority of its bytecode into instructions. You can, however, increase performance by utilising open-source implementations of the JVM. One example of such an implementation is HotSpot, which pre-compiles the bytecode so that it can run more quickly through the interpreter.

Kotlin and Java both have similar compilation procedures and runtime environments, therefore the performance differences between the two are minimal. This is because Kotlin and Java each have their own unique characteristics. Take, for instance:

In contrast, Java's use of function calls results in additional overhead memory being invoked, which Kotlin's inline functions eliminate. This results in improved efficiency.

Higher-order functions written in Kotlin are able to improve efficiency by avoiding the special call to InvokeDynamic made by Java lambdas.

When leveraging external dependencies, the performance of programmes written in Kotlin is slower than those written in Java since the resulting bytecode contains assertions for nullity checks.

Let's think back to when we first met. It is true in theory that using objects as base types (i.e., Kotlin's implementation) requires more allocation than using primitive data types (i.e., Java's implementation). This is because objects are more complex than fundamental data types. In contrast, while working with objects, Java's bytecode makes use of autoboxing and unpacking methods. These calls can result in additional computational overhead if they are utilised an excessive amount. For example, the String.format method in Java may only accept objects as input. This means that if you want to format a Java int, you must first enclose it in an Integer object before calling the String.format method.

There aren't any noteworthy differences between Java and Kotlin when it comes to performance or memory usage, generally speaking. It is possible to look at online benchmarks that demonstrate minute changes in micro-benchmarks, but these results cannot be extrapolated to the scale of a programme that is used in full production.

Unique Feature Comparison

There are several fundamental differences between Kotlin and Java, despite the fact that both languages share some commonalities. Since Kotlin has become Google's preferred programming language for Android development, I've discovered that the features that are most beneficial to me are extension functions and explicit nullability. When I use Kotlin, the Java features that I miss the most are the ternary operator and the protected keyword. On the other hand, when I use Kotlin, I use Kotlin.

Additional Things to Think About When Planning Your Android Project

When it comes to choosing between Kotlin and Java for use in a general-purpose setting, we have looked at a number of crucial aspects that should be considered. Nevertheless, no comparison between Kotlin and Java can be considered comprehensive without first addressing the issue that everyone's talking about: Android. Are you starting from scratch with an Android application and trying to decide whether to use Java or Kotlin as your programming language? Choose Kotlin without a doubt because it is Google's recommended language for use with Android.

Nevertheless, the answer to this issue is irrelevant for Android applications that already exist. From my perspective working with a diverse array of clients, the two most critical concerns are: How are you treating tech debt? and What are your plans for the future? and how are you ensuring a positive developer experience (DX) for your company?

So, how do you plan to handle the tech debt? In 2022, if your Android app is still utilising Java, it is likely that your organisation is prioritising the development of new features over the payment of technical debt. It is not hard to comprehend. Due to the high level of competition in the market, rapid iteration cycles for app upgrades are required. However, there is a covert consequence of tech debt: Since of this, there is a rise in expenses associated with each upgrade because engineers are forced to work around unstable code that is difficult to rework. It's not hard for businesses to get caught up in a never-ending cycle of IT debt and costs. It could be beneficial to take a step back and invest in long-term solutions, even if doing so necessitates doing extensive code refactoring or converting your codebase to a current language such as Kotlin.

And how are you making sure that your developers are satisfied with the DX platform? Support is necessary for developers at every stage of their careers, including:

Junior developers can benefit from having access to the appropriate resources.

Mid-level developers advance their careers by taking on leadership roles and teaching responsibilities.

Senior developers need the ability to architect and create code that looks good.

It is especially vital for top developers to pay attention to the DX, given that their expertise is transmitted downward and has an impact on all engineers. Senior developers have a passion for expanding their knowledge and gaining experience with new technologies. Maintaining a familiarity with emerging fashions and language releases will enable the members of your team to perform to the best of their abilities. This is necessary regardless of the language that the team chooses to work in, despite the fact that different languages have varied timelines: An engineer working on legacy code using a young language such as Kotlin has a greater chance of falling behind current trends in a shorter amount of time than an engineer using a more mature language such as Java.

Both Kotlin and Java are Highly Effective Languages

Although Java is useful in a broad variety of contexts, Kotlin has definitely overtaken it as the language of choice for the creation of new Android applications. This is not to say that Java is obsolete. Kotlin is the focus of all of Google's development efforts, and all of the company's newest technologies are written in Kotlin. Existing app developers should examine factors that go beyond our initial question of language choice and should think about integrating Kotlin into any new code they write (IntelliJ includes an automatic Java to Kotlin tool). Kotlin could be used by existing app developers as an alternative to Java.