Kotlin Vs Java – Difference Between Java and Kotlin

Kotlin vs Java

Android development is one of the coolest fields in computer science. The majority of the android apps use Kotlin and Java. In this blog, we are going to look at two very similar programming languages i.e. Java was launched in 1995 by Sun Microsystem which is a subsidiary of Oracle and Kotlin was officially released in 2016 by JetBrains.

This blog will let you explore the difference between Java vs Kotlin, the key features of each language, advantages, and disadvantages of each language.

What is Kotlin?

Kotlin is a platform-independent, open-sourced, statically typed, and versatile language influenced by Java. Kotlin with Java is a very demanding language for android developers. It runs on a Java virtual machine (JVM) and is a very good option for making android applications, server-side applications, etc. Kotlin combines object-oriented programming and functional programming in an unrestricted manner.

Key Features of Kotlin

  • The Kotlin language supports primary constructors, and if necessary, secondary constructors can also be used.
  • It reduces writing extra code, hence making it concise language.
  • It is an interoperable language which means it can easily call Java code and Kotlin code can be used by Java.
  • Kotlin supports String literals with embedded expressions. Additionally, the embedded expression value is most likely to be determined and concatenated into the string when it is executed.
  • In Kotlin, data classes (meant for storing data) are defined using the data keyword. Compilers automatically generate constructors, getters, and setters for data classes.
  • Kotlin provides fast compilation.
  • Kotlin handles NullPointerException. Therefore it is a null safety language. Kotlin has a safe call operator (?.) to handle null references. This operator executes any action only when the reference has a non-null value. Otherwise, it returns a null value. The safe call operator combines a null check along with a method call in a single expression.
  • In Kotlin, a singleton can be declared by simply declaring an object.
  • Kotlin is also said to be a tool-friendly language as Kotlin programs can be written using any Java IDE like eclipse, Netbeans, etc, or command line.
  • Smart cast is another popular feature offered by Kotlin in which immutable values are typecast explicitly, hence this feature reduces the cost of the application and enhances its speed and performance.

What is Java?

Java is a robust, secure, and object-oriented programming language. Earlier Java was known as Oak. Java is a computing platform as it has its own runtime environment JRE (Java Runtime Environment) and an API. The main objective of creating android apps is that they should work on any platform and that is why Java is used for this since it is a platform-independent language.

Key Features of Java

  • The ternary operator ‘?:’ in Java provides a shorter, more readable, and better-looking alternative to the if-else condition. Despite this, Java compiles ternary operators just like if-else statements.
  • Java is famous for WORA i.e. write once run anywhere. It is a portable language as it allows to carry java bytecode to any platform.
  • Java is a secure language and develops virus-free systems.
  • In Java, static members are created only once and shared by all instances of a class.
  • It is robust in nature and provides automatic garbage collection.
  • Provides automatic memory management as it is a multithreaded language.
  • Java is network-centric so it facilitates distributed computing.
  • The Java language supports what is known as checked exceptions. These exceptions must be declared in the code and caught as they occur.
  • Java supports widening conversions implicitly, so smaller data types can be converted to larger ones.
  • It is a dynamic language which means it is possible for programmers to modify the structure while running i.e it allows Runtime modifications.

Kotlin vs Java

Below are the difference between Kotlin and Java:

Static membersDoesn’t have static members for a class.It has static members for a class.
NullPointerExceptionNull Safety is available in this language using the safety call operator.Null safety is not available in java.
WildcardsWildcard types are not available.Wildcard types are available. These are a special kind of type argument that controls the type safety of the use of generic (parameterized) types.
DeploymentEasy to deploy Kotlin code.Hard to deploy Java code.
Secondary ConstructorThere is a concept of secondary constructors in Kotlin. And there can be more than one secondary constructor. It allows initialization of variables and provides some logic to the class as well.No such concept of the secondary constructor is there but it can have multiple constructors.
SemicolonSemicolons aren’t required in Kotlin programs.Semicolons are required in Java programs.
ExpressionExpressions (variables, operators, method calls) are also supported by the Kotlin string template.Java string doesn’t support expressions like Kotlin.
Lazy loadingLazy Loading is another feature provided by Kotlin. It is preferred when the initialization of the property has a larger impact on computational resources like memory, CPU, etc.)No concept of lazy loading is there in Java.
DataTypeAny variable data type specification is not required.Variable data type specification is required.
Smart castIt provides a smart cast feature i.e Kotlin compiler track tracks the condition inside if expression.Do not provide a smart cast feature.

Pros and Cons of Kotlin

Below are some of the benefits of Kotlin:

  • Kotlin provides a clear, compact, and common codebase that makes the code in the production environment more stable and consistent.
  • Writing new code in Kotlin takes less time as compared to other programming languages as it provides an almost automated way of creating data classes.
  • Larger apps are divided into smaller layers.
  • It offers user-friendly and understandable coding norms.
  • Kotlin is safe against null pointer exceptions.
  • Easy, understandable, and user-friendly coding norms are offered.
  • Increases team efficiency due to its easy and compact syntax. 
  • Kotlin codes are quite easier to deploy and maintain.

Now we will look through some disadvantages of Kotlin:

  • Since Kotlin is not so popular, the developer community is small, hence learning material and professional aid is less.
  • Since Kotlin is a highly declarative (non-procedural or high level) language, it generates a huge amount of boilerplate corresponding to JVM bytecode.
  • Compilation speed is slow as compared to Java.
  • It has a steep learning curve, if one decides to switch teams to Kotlin just because of its concise syntax then it proves to be a real challenge.

Pros and Cons of Java

Below mentioned are some of the advantages of Java:

  • A huge array of third-party libraries are available.
  • Error detection and solving are easier as there is a concept of exceptions.
  • Detailed documentation of Java is available so learning becomes easier.
  • The developer community is very large.
  • Reusable code and standard programs are developed easily through Java.
  • It is easy to navigate libraries in Java.
  • It is faster than other programming languages and therefore provides excellent performance.
  • The multithreaded environment of Java allows the user to perform multiple tasks simultaneously in a program. 

Some of the disadvantages of Java are listed below:

  • Just in time(JIT) compiler makes the program slow as compared to other languages.
  • Takes lots of system memory and has high processing requirements.
  • In Java, aid for low-level programming constructs like pointers is not supported.
  • A lot of manual work is required which increases potential errors.
  • It is not very suitable for Android API design.

Java vs Kotlin: Which one is better?

Taking into consideration all the difficulties of Java, especially the problems with Null pointer exceptions, Kotlin takes the upper hand among the two. Java is still an important language for android development as the android operating system is based on it but the features offered by Kotlin like superior type system to Java, incremental change of code, a combination of language database, and less coding make it more in demand for future use. 


Kotlin is emerging very fast and is providing developers with ample opportunities to experiment with modern programming, hence proving to be an excellent programming language for android app development. Kotlin is almost like Java and therefore we can go with Kotlin as it is accomplishing whatever standard programming should do.


Q: Is Kotlin easier than Java?

It totally depends on the level of experience with programming. Learning a language can be quite challenging at first. However, as soon as there is a sufficient amount of learning materials available in the market, it will become more convenient. Since Java is an older language so its resources are more, so in an earlier stage of learning, one should start with Java and then can go to Kotlin for a better understanding of concepts in less time.

Q: Can I learn Kotlin without Java?

Yes, one can learn Kotlin without Java but it is better to know the basics of Java. Having knowledge of any programming language makes it easier to learn and grasp things faster.

Q: What companies use Kotlin?

Well, renowned companies like Google, Netflix, Amazon, Pinterest, Uber, Trello, etc use Kotlin. In fact, Google has declared Kotlin as its first programming language for android development. Around 1000 plus companies are using Kotlin as their production language.

Q: What does Java have that Kotlin does not?

  • Java has the concept of checked exceptions which makes the detection of errors easier.
  • Primitive types that are not classes and bytecode use primitives wherever possible, but they are not explicitly available.
  • Wild cards are replaced with declaration site variance and type projections. 
  • Static members are there in Java. 
  • So these are some of the concepts which Java has but Kotlin doesn’t.

Q: Should I switch from Java to Kotlin?

Switching from Java to Kotlin will be worth it and will be in the long run. The creation of android apps through Kotlin is easier because it looks like Kotlin is developed keeping android in mind. There will be a learning curve in switching but since Kotlin is interoperable with Java so it can be very fruitful for developers.

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