Java and Kotlin: Important Differences That You Should Know

Java and Kotlin: Important Differences That You Should Know

The confrontation between Java and Kotlin is one of the most high – profile topics of recent years. On the one hand, Java is a time-tested and widely used version, on the other hand, Kotlin has its own advantages. Both programming languages are used in the development of programs for devices running on the Android platform.

Java is an object-aligned programming language. Programs or applications developed in Java will be carried out in a JVM, that is, Java virtual machine. With the help of it we will be able to run the same program on various different platforms and systems/devices etc. Kotlin is a new programming language. It can function on some modern features too. Kotlin is also a statically typed programming language. Kotlin can be helpful choice for building server-side applications. These applications in turn can enable the users to write concise and expressive code.

What is Java?

Java is said to be an OOP, that is, object-oriented programming language which came to usage in 1995. If you want to run a Java program on the browser you need to use Java applets. Java applets are the ones which are embedded as a plugin. So Java is mostly used for standalone applications or back-end development. The design of Java was created by James Gosling and its major implementation was OpenJDK. Java is prioritised by most of the developers when it comes to Android application development as Android itself is written in Java.

Features of Java

  • It helps in writing code once and it has the tendency to run it on almost any computing platform.
  • It has been created by the developers for developing object-assigned applications.
  • It is a multithreaded language which enables you to perform automatic memory management.
  • It eases and simplifies distributed computing as it’s network-centric.

What is Kotlin?

Kotlin is a complete new programming language build by programmers from IDE Jet Brains which adds to it some modern features. It has first brought into the picture in the year 2011. However, the official release of it was in 2016. It is an open-source language too. Kotlin is also a fixed typed programming language just like Java, C++. It is also based on Java Virtual Machine. However, it can be gathered to JavaScript, Android and Native for creating code and run on iOS. Kotlin is fully adaptable with existing Java stacks along with a smooth learning curve. Switching from Java to Kotlin is quite simple as you only need to install a Plugin.

Features of Kotlin

  • It provides with Trimmed Coding.
  • Kotlin potentially makes use of JVM. JVM in return blends the features of OOPs and functional-oriented programming.
  • It also provides with the feature of fast compilation.
  • Kotlin can bear a variety of extension functions without modifying the code
  • You can also write Kotlin code with the help of IDE or the command-line interface.
  • Smart feature casting really helps you to hack down the application costs and enhances its speed or performance.

Java vs Kotlin Comparison

So, the important question that lies here is whether one should switch to Kotlin from Java or not? Well, the choice of selecting either of them depends upon the preferences. And to go to that part it is important to understand the distinction between the two programming languages.

Checked Exceptions

One major difference between Java and Kotlin is that the second has no facilities for checked exceptions. Thus, there is no need to find and claim any exceptions.

Let’s say a developer working in Java finds it useless to utilize try/catch blocks in the code. And when such turn of events occur, then the omission made by Kotlin can be reviewed as a welcome change. However, it will take an opposite turn if the developer lays their trust in the fact that checked exceptions supports error recovery and the creation of robust code.

Code Conciseness

Doing a comparison between Java class with Kotlin class exhibits the conciseness of Kotlin code. In order to perform the same operation, a Kotlin class entails for less code.

Let’s say, a specific division where Kotlin can remarkably minimise the total amount of boilerplate code is findViewByIds.

Kotlin Android Extensions allows bringing in a reference to a View into the Activity file. This in turn, helps to work with that View as if it was part of the Activity.

Null Safe

In Java, NullPointerExceptions does not go well for developers. It enables users to allocate null to any variables. However, while retrieving an object reference having null value increases a null pointer exception. And this is what the users need to handle.

It’s a by default feature of Kotlin, that all types of variables are non-null able, that is, you won’t be able to designate null values to any type of variables or objects. If you try to designate or return null values, Kotlin code will fail during compile-time.

Extension Functions

In Java, if you want to expand the performance of existing class you need to build a new class and take over the parent class. So Extension functions are not obtainable in Java.

Kotlin offers developers the potential to expand an existing class with new performance. You can also expand the performance by adding the name of a class to name of the new function.

Coroutines Support

In Java, whenever you begin with a long-running network I/0 or CPU Intensive operations, the relative thread will be blocked. Android is a single-threaded by default. Java offers the tendency to build multiple threads in the background and run. However, managing them is a complex task.

In Kotlin, you can also form multiple threads to function these long-running intensive operations. Also you will have coroutines support. The support from coroutines will remove execution at a certain point without having to block the threads while implementing long-running intensive operations.

No checked exceptions

While using Java, exceptions support will help the developers to declare and catch the exception. This can eventually lead to robust code with good error handling.

On the contrary, while using Kotlin, you don’t have checked exceptions. Therefore, a developer does not have to declare or catch the exceptions.

Data classes

While using Java, you need to have a class. A class is highly needed to hold data and nothing else. For this, you need to describe constructors, variables to store data, getter and setter methods, hashcode(), toString(), and equals() functions.

And while using Kotlin, if you need to have classes which can hold data, you can declare a class with a keyword “data” in the class definition. Further, the functionality of a compiler will take care of all of this work like building constructors, getter, and setter procedures for various fields.

Smart casts

When working on Jana, you will have to keep a proper check on the type of variables. And doing so will emit according to our operation.

And when working on Kotlin, smart casts will hold these casting checks with keyword “is-checks”. And this keyword will check for any kind of unchangeable values and carry out implicit casting.

Type inference

While using Java, we need to specify a type of each variable explicitly while declaring.

In Kotlin, you don’t need to state the type of each variable explicitly on the basis of an assignment. If you want to state explicitly you can do freely.

Extension Functions

Kotlin enables the developers to expand a class with new functionality via extension functions. Thus, these components are available in other programming languages such as C#. However, they are not available in Java.

Creating an extension function is quite simple while working in Kotlin. It is done by affixing the name of the class which had to be expanded to the name of the function being formed. And for the sake of calling the function on the instances of the extended class, one needs to use the ‘.’ notation.

Implicit Widening Conversions

There is no encouragement for the conversions of the implicit widening for numbers in Kotlin. Therefore, smaller types are unable to get transformed to bigger types. While Java has fully shown encouragement for implicit conversions, Kotlin still needs to perform an explicit conversion. It is done in order to achieve the whole transformation.

Functional Programming

Java doesn’t need a running programming support till Java 8. However, while building Android applications, it encourages the only subdivision of Java 8 features.

Kotlin is a blend of procedural and functional programming language which comprises of various useful methods such as lambda, operator overloading, higher-order functions, and lazy evaluation, etc.


Thus, this entire article shows a comparison between Java vs Kotlin. I hope you will have a better sense of understanding for these Java vs Kotlin languages after reading this Java vs Kotlin article. Clearly Java has few advantages over Kotlin.

For general-purpose programming, Java gains the benefits. On the other side, more and more developers and organizations are inheriting Kotlin. They are doing so, to more swiftly develop the Android applications.

Both Java and Kotlin have their own advantages over the other. The debate about these advantages of the two is the greatest and has just begun. And this comparison between the two does not seem to end anytime soon.



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