Decoding Kotlin vs. Java for Android App Development

Introduction to Kotlin and Java

Choosing between Kotlin and Java is a key decision for Android app developers today. While Java has been a staple of Android development, Kotlin offers numerous advantages like null safety, coroutines, and more concise syntax. In this post, we’ll compare Kotlin vs Java, discussing how each language impacts performance, developer productivity, and interoperability in mobile development. We’ll also look at Kotlin multiplatform and its potential for cross-platform development. By understanding the differences between the two languages, you can make the best choice for your mobile development needs.

Understanding Java and Kotlin Programming Languages

When choosing a language for mobile development, particularly for Android app development, Java and Kotlin are the top contenders. Each has its own strengths in terms of performance, coding efficiency, and developer productivity. Here's a comparison of the two.

Java

Java is the native language used by Android, and applications that communicate with the operating system and directly use the hardware use it. This language allows the creation of any program and supports almost all types of machines and operating systems, including Android, Windows, and Linux. It was developed by Sun Microsystems (now the property of Oracle), and one can use microservices with it. Java is widely known for its object-oriented programming and legacy applications support.

Kotlin

Kotlin, on the other hand, is a modern language created as an improvement over Java. It is inspired by Java but comes with additional features that enhance developer productivity and coding efficiency. Kotlin is clear and concise and carries fewer formalities and rules compared to Java and other programming languages. It offers features like null safety, coroutines, extension functions, and type inference, which contribute to its performance and syntax simplification. Kotlin is fully compatible with Java and runs on the JVM (Java Virtual Machine), making it a perfect fit for Android app development.

Kotlin vs Java: Key Differences Explained

Developing Android applications is a powerful way to drive success for your business, but choosing the right programming language can be a real dilemma. Many developers initially believe Java is the best option since it's widely used and praised. However, with the arrival of Kotlin, this belief has been challenged, prompting developers to search for answers to questions like:

• Which language is best for Android development?

• Is Kotlin better than Java for Android app development?

• What are the advantages of Kotlin vs Java?

And the list goes on. In order to resolve issues and give you a clear vision, we'll compare Java and Kotlin and help clarify which is the best choice for your Android development needs. Let’s dive in!

Feature Showdown With Syntax

Although Java remains an officially supported language for writing Android apps, you might still wonder why developers are making the switch to Kotlin. After all, Java has been proven to work well for Android development. However, there are compelling reasons why adopting Kotlin can significantly improve your development process. Here's why switching to Kotlin is one of the best decisions you can make.

Benefits of Java and Kotlin for Development

Benefits of Java

Listed below are the benefits of Java:

• Multiplatform: It works on almost any device, server, or operating system, making it versatile for various environments.

• Robust Coding: Java is designed to prevent memory corruption or data compromise, ensuring that applications remain secure and stable.

• Object-Oriented: Java enables the creation of modular applications, allowing code reuse and enhancing robustness.

• Ready-to-Use Libraries: There is a wealth of third-party code available for Java, reducing the time required for development.

• Ease of Use: When compared to other languages, Java is relatively easy to use, compile, and debug, simplifying the deployment process.

• Open-Source: As an open-source language, Java benefits from safety and reliability, with many of its libraries maintained by trusted companies like Google, Apache, and others.

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Benefits of Kotlin

Listed below are the benefits of Kotlin:

• Faster Application Deployment: Kotlin is faster to compile, lightweight, and prevents applications from growing too large, making deployment more efficient.

• Concise Code: Kotlin is less verbose than Java, meaning the code is smaller and less prone to bugs, leading to cleaner and more maintainable applications.

• JVM Compatibility: Kotlin compiles to bytecode, which can be executed in the JVM, ensuring that libraries and frameworks built with Java work seamlessly in Kotlin projects.

• Enhanced Developer Productivity: With features like auto-completion and error detection in Android Studio, Kotlin improves the development experience and reduces compile-time errors.

• Null Safety: Kotlin is designed to prevent NullPointerException (the "Billion Dollar Mistake"), ensuring greater safety and reliability in applications.

• Coroutines and Interoperability: Kotlin supports coroutines for asynchronous programming and offers interoperability with JavaScript, making it a strong choice for both mobile and web development.

Challenges in Using Java and Kotlin

Challenges of Java

Below are the challenges of Java:

• Complex Syntax: The syntax of Java can be more complicated and cumbersome compared to languages like C++ or Python.

• Device Incompatibility: It can be difficult to access certain content or features that are incompatible with the device or equipment being used.

• Limited Access to New Enhancements: Accessing the latest Android development features can be more challenging with Java.

• Android API Design Issues: Sometimes, Java encounters compatibility issues or problems when interacting with Android API design.

• Test-Driven Development: Writing tests for Java applications requires more code and has a higher risk of programming errors and bugs.

• Performance: Java tends to be slower compared to other programming languages and uses more system memory.

Challenges of Kotlin

Below are the challenges of Kotlin:

• Popularity: Kotlin is not as widely adopted as other languages like Java, meaning its developer community is smaller.

• Initial Code Readability: Due to its concise syntax, Kotlin can be difficult to read and understand at first, especially for developers unfamiliar with it.

• Limited Support: As a newer language, Kotlin has fewer libraries, blog posts, and tutorials available, and its support community is still growing.

• Learning Curve: The concise syntax of Kotlin can present a steep learning curve, making it challenging for teams to switch from other languages.

• Lack of Experienced Developers: There are fewer Kotlin developers available in the market, which makes finding an experienced mentor or team member more difficult.

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Real-World Applications of Java and Kotlin

Applications of Kotlin

• Spotify
• Twitter
• Cash App
• Signal
• Amaze File Manager

Applications of Java

• Pinterest
• Trello
• Evernote
• Twidere for Twitter
• Shadowsocks

Key Features of Java and Kotlin Compared

Null Safety

NullPointerException or NPE is one of the main drawbacks of it, and the only possible reason for NPE is an explicit call to throw NullPointerException. Some of the data inconsistency is related to initialization or other issues caused by external code. As already mentioned in the above section in them, it avoids NullPointerException. It fails at compile-time whenever a NullPointerException may be thrown.

Data Classes

There are data classes that lead to the auto-generation of boilerplates, such as equals, hashCode, toString, getters/setters, and much more. Consider the following example: /* Java Code */

class Book {
    private String title;
    private Author author;
    public String getTitle() {
        return title;
     }
    public void setTitle(String title) 
    {
        this.title = title;
    }
    public Author getAuthor() {
        return author;
    }
    public void setAuthor(Author author) 
    {
        this.author = author;
    }
}

But in it, the same above class can be defined concisely in one line – /* kotlin Code */

data class Book(var title: String,
var author: Author)

Extension Functions

It allows us to extend the functionality of existing classes without inheriting from them. This means that it provides the ability to develop a class with new functionality without having to inherit from the class. Extension functions do this. To declare an extension function, we need to prefix its name with a receiver type, i.e. the type being extended. The following adds a swap function to MutableList –

fun MutableList < Int > .swap(index1: Int, index2: Int) {
    val tmp = this[index1]
    this[index1] = this[index2]
    this[index2] = tmp
}

The ‘this’ keyword inside the extension function corresponds to the receiver object passed before the dot. Now we can call such a function on any MutableList –

val abc = mutableListOf(1, 2, 3)
abc.swap(0, 2)

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Smart Casts

When it comes to casts, its compiler is intelligent. In many cases, one does not need to use explicit cast operators in Kotlin, but there are “is-checks” for immutable values, and inserts cast automatically when required –

fun demo(x: Any) {
    if (x is String) {
        print(x.length) // x is automatically cast to string
    }
}

Type Inference

fun main(args: Array < String > ) {
    val text = 10
    println(text)
}
/* explicitly defined */
fun main(args: Array < String > ) {
    val text: Int = 10
 println(text)
}

Functional Programming

The main important thing in performance is that it is a functional programming language. Basically, it consists of many useful methods, which include higher-order functions, lambda expressions, operator overloading, lazy evaluation, operator overloading, and much more. Functional Programming makes it much easier when it comes to collections–

fun main(args: Array < String > ) {
    val numbers = arrayListOf(15, -5, 11, -39)
    val nonNegativeNumbers = numbers.filter 
   {
       it >= 0
   }
   println(nonNegativeNumbers)
}

Output – 15, 11 Higher-order functions are those functions that take functions as a parameter and also return a function. Consider the following code:-

fun alphaNum(func: () -> Unit) {}

In the above code, “func” is the name of the parameter, and “ ( ) -> Unit ” is the function type. In this case, we are saying that func will be a function that does not receive any parameter and does not return any value. Lambda expression or an anonymous function is a “function literal,” i.e., a function that is not declared but passed immediately as an expression. An Example of a Lambda Expression –

val sum: (Int, Int) - > Int = {
 x,
 y - > x + y
}

In the above example, we simply declare a variable ‘sum’ that takes two integers, adds them together, and returns the total as an integer. Then we just use ‘ sum(2,2) ’ in order to call it. Pretty cool, huh? Anonymous Function in Android is a function that allows us to specify the return type, and in this, the function name is omitted. Consider the following example:- Either this way –

fun(x: Int, y: Int): Int = x + y
or This Way
fun(x: Int, y: int): Int {
 return a + b
}

Kotlin vs Java: Which is the Best Choice?

Kotlin offers significant advantages over Java in various areas, particularly when it comes to Android programming and enterprise applications. While Java is still widely used, Kotlin provides several features that make it a better option for modern development. Here's a breakdown of why Kotlin can be considered superior.

Interoperability and Migration

Kotlin is fully interoperable with Java, offering an incremental change of code and a superior type system. It also provides an easy migration path from Java with backward compatibility. This makes transitioning from Java to Kotlin smoother while retaining the benefits of both languages. Features like more declarative code, reduced verbosity, and support for mixed-language databases make Kotlin more expressive and future-proof for enterprise and mobile development.

Compiles to JVM bytecode or JavaScript

Like Java, Kotlin compiles to JVM bytecode or JavaScript. Bytecode allows the source code to be run on any platform once compiled and executed by the JVM (Java Virtual Machine). This means that Kotlin can run seamlessly on different devices and operating systems, just like Java, ensuring wide compatibility and portability.

Full Access to Java Frameworks and Libraries

Kotlin can use all existing Java frameworks and libraries, including advanced frameworks that rely on annotation processing. It integrates easily with popular build systems like Maven and Gradle, making it easy for developers to leverage the extensive ecosystem already built for Java while taking advantage of Kotlin's enhanced features.

Rapid Learning Curve

Kotlin is approachable and can be quickly learned, particularly for developers already familiar with Java. The syntax is clean, intuitive, and more straightforward than Scala, making it easier to use and understand. This reduces the time needed to get up to speed and improves developer productivity.

Automatic Code Conversion

With JetBrains' integration in IntelliJ IDEA, Kotlin supports automatic conversion from Java code, saving developers time and effort. This feature reduces the need to retype mundane code and makes transitioning from Java to Kotlin even more efficient.

Null Safety

Kotlin addresses one of Java's most significant drawbacks—NullPointerExceptions—by offering null safety. In Kotlin, the language prevents NullPointerExceptions by refusing to compile code that attempts to assign or return null where it's not explicitly allowed. This reduces runtime errors and improves the stability and reliability of applications.

val name: String = null // tries to assign null, won’t compile.
fun getName(): String = null // tries to return null, won’t compile.

Code reviews are not a problem

Since Kotlin's primary focus is on readable syntax, code reviews become easier. Even developers unfamiliar with Kotlin can quickly understand the code, leading to more efficient collaboration and fewer misunderstandings during the review process.

Additional Features of Kotlin for Developers

Listed below are the features of the Kotlin language:

Requires Less Code

Kotlin allows for more concise code compared to Java. The language is less verbose, meaning you can achieve the same functionality with fewer lines of code. This leads to fewer bugs, reduced scheduling time, and overall cost savings for the project.

Secure

Kotlin is designed to be safe against NullPointerExceptions (NPE), a common issue in Java. Kotlin warns developers of potential null situations during compile-time. Developers must explicitly specify if an object can be null and check its nullity before using it. This reduces the chances of data loss and bugs in the application.

Easy to Learn

One of the most significant benefits of Kotlin is its simplicity. Developers can understand most of the Kotlin code without having written it before. This makes it accessible to beginners and improves developer productivity for those transitioning from other languages, especially Java.

Fun to Use

While subjective, many developers find Kotlin enjoyable because of its modern features and efficient syntax. In contrast, Java can become tedious due to its boilerplate code and limitations, leading to frequent errors and a more cumbersome development experience.

Smart Casts

Kotlin's compiler is intelligent when it comes to casting. In many cases, developers do not need to use explicit cast operators. Kotlin automatically inserts a cast when necessary, particularly after using an is-check on immutable values, making the code cleaner and more efficient.

Type Inference

With Kotlin, you don’t always need to specify the type of each variable explicitly. Kotlin uses type inference to automatically determine the type of a variable based on its value. If needed, you can still define the data type explicitly, offering flexibility in how variables are declared.

Functional Programming

Kotlin supports functional programming paradigms. It includes useful features such as higher-order functions, lambda expressions, operator overloading, and lazy evaluation, making it a powerful language for handling complex transformations, particularly in collections and asynchronous programming.

Business Benefits of Adopting Kotlin for Projects

• Shallow Adoption Risk: Kotlin is interoperable with Java, allowing businesses to adopt it gradually with minimal risk.

• Easy Learning Curve: Kotlin is easy to learn, and developers can quickly get up to speed, reducing training time.

• Strong Community Support: Backed by JetBrains, Kotlin has a strong support network, ensuring reliability and minimal downtime.

• Functional and Procedural Programming: Kotlin combines both functional and procedural programming, offering flexibility for various applications.

• Versatile Development: Kotlin can be used for server-side, client web, and Android development, making it a versatile tool for businesses.