Kotlin vs. Java: Which programming language should you learn?

In today’s rapidly evolving technological landscape, programming stands as a cornerstone of innovation and progress. With the advancement in technology, our ability to understand and write code enables us to create solutions to complex problems. Moreover, it’s generally agreed that the global economy is driven by digitalization, so proficiency in programming opens doors to diverse career opportunities. It’s not uncommon to see people with noncomputing backgrounds learning programming because they want to develop something by themselves according to the idea they have in their minds.

In this blog, we’ll understand the basic concepts of Java and Kotlin and learn which language to use in any scenario. We’ll also discuss the benefits and drawbacks of each language.

Java language#

Kotlin language#

Features of Java#

Some of the key features of Java are discussed below:

• Platform independence: It allows the same code to be executed on different platforms that have a JVM installed. This is one of the major features of Java that directly corresponds to the write once, run anywhere (WORA) principle.

• Simplicity and familiarity: Its syntax is simple, which makes it easy to learn. This is also helpful for those who have experience of development in C/C++ because the syntax is similar to that of Java.

• Object-oriented paradigm:  It’s an object-oriented language that naturally makes our code modular, reusable, and easy to maintain.

• Multithreading: It supports the creation of multiple threads that are necessary to implement asynchronous functions. These functions can be used for all the tasks that need to be executed in the background, making our applications more responsive.

• Rich standard library: It has a very rich collection of standard libraries that makes the tasks of performing I/O, networking, streaming, and many other types of operations easy.

• Robustness: It’s well-known for its robustness, thanks to its automatic memory management (garbage collection), exception handling, and type checking.

• Dynamic loading: It has an excellent feature where classes are only loaded on-demand during the execution of a program.

• Large community support: It has a large community of support because of its usage at a massive level. This leads to the provision of a wealth of resources, frameworks, and support for newcomers and experienced developers alike.

Features of Kotlin#

Some of the key features of Kotlin are discussed below:

• Smart casts: It has the ability to automatically typecast variables if certain conditions are true. This eliminates or reduces the need for manually type casting variables.

• Compact code: It has a compact and expressive syntax, which greatly reduces the boilerplate code. This leads to smaller-sized programs that are easier to read and debug.

• Null safety: It has a very nice feature of null safety built into its type system that prevents the occurrence of the common error of null pointer exception.

• Asynchronous programming: It has an excellent feature of coroutines that help in implementing asynchronous functions without using the complex traditional threading.

• Higher-order functions: It supports the implementation of higher-order functions and Lambda expressions that help write concise code.

• Extension functions: It supports the addition of new functions to already existing classes without changing their source code. This provides a great way to enhance the functionality of any library.

• Interoperability with Java: It’s possible to use any Java library and framework in Kotlin because it’s completely interoperable with it.

• Interoperability with JavaScript:  It’s possible to compile a Kotlin program to JavaScript. This enables us to write front-end web applications using it.

• Default arguments: It allows us to provide default values for function parameters. This way, we can call a function with partial arguments by using named parameters.

• Operator overloading: It’s possible to write custom implementations of operators in Kotlin. This helps in writing custom logic that might be needed in some scenarios.

• Sealed classes: It allows us to write sealed classes that can be used to define a closed set of subclasses. We can implement strict class hierarchies using this.

• Type inference: It allows us to omit explicit type declarations while still ensuring strong typing.

• Ranges and progressions: It provides support for iterating over a range of values that makes it easy for us to work with a collection of data.

Let’s summarize the disadvantages of both languages in a tabular manner.

Syntax comparison: Java and Kotlin #

Let’s take a look at the basic syntax of Java and Kotlin by printing an array.

The “Hello, World!” program in Java#

Let’s write a simple program in Java that will print the message “Hello, World!” on the console.

The “Hello, World!” program in Kotlin#

In Kotlin, for printing anything on the console, we just need to call the println method.

One of the most significant differences between Kotlin and Java is the syntax. From the code examples above, we can see that the Kotlin version is shorter and more expressive because it eliminates the unnecessary boilerplate code, such as type declarations and semicolons, and uses more natural language constructs. In Kotlin, we can define the class and its fields in a single line.

Additionally, Kotlin supports type inference. It means that we don’t have to specify the data type of a variable explicitly. If we refer to line 2 in the Kotlin example above, we declare a variable named message without explicitly specifying its data type. The compiler will automatically determine the data type based on the value that we assign to the variable. However, if we refer to line 3 of the Java example above, we explicitly mention the data type of the variable message.

The ease of syntax of any programming language is a subjective matter and depends on the language the person has previous experience with. However, many developers find Kotlin to have a more modern and expressive syntax, which can lead to more concise and readable code compared to Java. It should also be noted that if someone already has experience in Java, then learning Kotlin will be quite easy for them.

Disadvantages of Java#

While Java is a widely used programming language, it does have some disadvantages. Some of them are listed below:

• Verbosity: Programs written in Java tend to be more lengthy than other modern languages like Python. This means programmers have to write more code in Java to implement the same functionality compared to these modern languages.

• Memory consumption: Programs written in Java generally consume more memory compared to languages like C or C++.

• Limited hardware access: Java was designed to be a platform-independent language, so direct hardware access was never a priority. As a result, it has very limited direct hardware access.

• Slower execution speed: Programs written in Java are still not as fast in execution as programs in some lower-level languages like C or C++.

• Lack of low-level manipulation: Java abstracts away low-level details for the sake of portability and safety. However, this means that low-level memory manipulation, common in languages like C, isn’t directly supported in Java. This might be a disadvantage in scenarios where such manipulation is necessary.

• No multiple inheritance:  Java only supports single inheritance, which can limit certain design patterns.

• No unsigned types: Java has no support for unsigned data types.

Disadvantages of Kotlin#

• Slow compilation speed: Kotlin’s compilation speed has been reported to be slower compared to Java in some cases.

• Limited official documentation: Kotlin has limited official documentation. Although it’s continuously updating, it’s still not as extensive as Java’s.

• Size of the standard library: Programs written in Kotlin can lead to larger binary sizes if developers are not cautious about what parts of the standard library are included.

• Compatibility with older Java versions: Although Kotlin is designed to be interoperable with Java, there might be limitations when working with older Java versions.

• Community: Kotlin’s community is growing rapidly, but it’s still not as extensive as Java’s.

• Build system complexity: For Kotlin, Gradle is the primary build system. Although it’s powerful, configuring and understanding Gradle build files can require additional effort compared to simpler build systems.

Let’s summarize the disadvantages of both languages in a tabular manner.

This wraps up our blog about Java vs. Kotlin and which language you should learn. We started by discussing the history of Java and Kotlin. We then discussed the features of Java and Kotlin, comparing their syntax to determine which is more expressive. After that, we discussed the drawbacks of both languages. We can conclude that both languages have their pros and cons, and it’s up to the learner to choose the language of their preference, keeping this discussion in mind.

Your next learning steps#

• To deepen your understanding of the Java and Kotlin programming languages, we strongly recommend you look through the following selection of specialized courses on the Educative platform:

  • Learn Java from Scratch

  • A Complete Guide to Java Programming

  • Kotlin Crash Course for Programmers

  • The Ultimate Guide to Kotlin Programming

• Don’t pass up this chance to increase your knowledge and expertise in Java and Kotlin. Take the first step toward becoming an expert developer in Java and Kotlin by immediately enrolling in Educative courses!