Kotlin vs. Java | What is the difference between Kotlin and Java | 2021

In this tutorial, we’re going to discuss the main difference between Kotlin and Java. But before discussing the Kotlin and Java difference, let’s first learn “What is Kotlin?” and “What is Java?”.

What is Kotlin?

Kotlin is an open-source statically typed programming language that runs on Java Virtual Machine (JVM). It combines Object Oriented Programming (OOPs) and functional programming in unrestricted, self-sufficient, and distinctive platforms. It also allows the twinning of functionalities by miniature codes. Kotlin is a general-purpose programming language that was designed by JetBrains.

What is Java?

Java is a general-purpose, class-based, object-oriented programming language designed for having lesser implementation dependencies. Java is fast, secure, and reliable, therefore. It is widely used for developing Java applications in laptops, data centers, game consoles, scientific supercomputers, cell phones, etc.

Difference between the Java and Kotlin

Java vs. Kotlin

Null Safe

In Java, NullPointerExceptions causes huge frustration for developers. It allows users to assign null to any variables but while accessing an object reference having null value raises a null pointer exception which user needs to handle.

In Kotlin, By default, all types of variables are non-nullable (i.e. we can’t assign null values to any type of variables/objects). If we try to assign or return null values, the Kotlin code will fail during compile-time. If we really want a variable to have a null value, we can declare as follows: value num: Int? = null

Extension Function

In Java, If we want to extend the functionality of the existing class we need to create a new class and inherit the parent class. So Extension functions are not available in Java

Kotlin provides developers the ability to extend an existing class with new functionality. We can create extend functions by prefixing the name of a class to name of the new function.

Coroutines Support

In Java, whenever if we initiate a long-running network I/0 or CPU Intensive operations, the corresponding thread will be blocked. As Android is a single-threaded by default. Java provides the ability to create multiple threads in the background and run but managing them is a complex task.

In Kotlin, We can create multiple threads to run these long-running intensive operations but we have coroutines support, which will suspend execution at a certain point without blocking threads while executing long-running intensive operations.

No checked exceptions

In Java, We have checked exceptions support which makes developers declare and catch the exception which ultimately leads to robust code with good error handling.

In Kotlin, we don’t have checked exceptions. So developers don’t need to declare or catch the exceptions, which have advantages and disadvantages

Data classes

In Java, suppose we need to have a class which needs to hold data but nothing else. For this we need to define constructors, variables to store data, getter and setter methods, hashcode(), toString(), and equals() functions.

In Kotlin, If we need to have classes which need to hold data we can declare a class with keyword “data” in the class definition then the compiler will take care of all of this work such as creating constructors, getter, setter methods for different fields.

Smart casts

In Java, We need to check the type of variables and cast according to our operation.

In Kotlin, smart casts will handle these casting checks with keyword “is-checks” which will check for immutable values and performs implicit casting.

Type inference

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

In Kotlin, we don’t need to specify the type of each variable explicitly based on assignment it will handle. If we want to specify explicitly we can do.

Functional Programming

Java doesn’t have functional programming support till Java 8 but while developing Android applications it supports the only subset of Java 8 features.

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

So, which is better?

  • When considering all the pitfalls of Java, especially the problem with NullPointerExceptions, Kotlin seems to be the better one among the two.
  • Although Java is still an essential language for every android app development as the Android OS itself is based on the same.
  • If you are looking to future-proof your android app development services, then you should hire Kotlin developers for the same.

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Hi everyone, myself Golap an Android app developer with UI/UX designer.

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Golap Gunjan Barman

Golap Gunjan Barman

Hi everyone, myself Golap an Android app developer with UI/UX designer.

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