Java vs Kotlin

Differences Between Java and Kotlin

Java is an object-oriented programming language. Programs or applications developed in Java will execute in a JVM (Java virtual machine ) by which we can run the same program on multiple platforms and systems/devices etc. Kotlin is a new programming language, which handles some modern features. Kotlin is also a statically typed programming language. Kotlin is a good choice for developing server-side applications, allows users to write concise and expressive code.

What is Java?

Java is an OOP (object-oriented programming) language which came to usage in 1995. Java was developed at sun microsystems which later acquired by Oracle. If we want to run a Java program on the browser, we need to use Java applets embedded as a plugin that is not suggested. So Java is mostly used for standalone applications or back-end development. James Gosling designed Java, and its major implementation was OpenJDK. Java is the primary choice for most of developers when it comes to Android application development as Android itself is written in Java.

What is Kotlin?

Kotlin is a new programming language developed by programmers from IDE Jet Brains, which handles some modern features to it. It has first appeared in the year 2011 and the official release in 2016, and it is an open-source language. Kotlin is also a statically typed programming language like Java, C++, which based on JVM (Java Virtual Machine), but it can be compiled to JavaScript, Android and Native also for building code and run on iOS. Kotlin is fully compatible with existing Java stacks with a smooth learning curve. Switching from Java to Kotlin is very easy as we just need to install a Plugin. The Google I/O keynote announced that they are making Kotlin an officially supported language for Android application development.

Head To Head Comparison Between Java and Kotlin (Infographics)

Below is the Top 8 Comparisons Between Java vs Kotlin

Key Differences Between Java and Kotlin

Both are popular choices in the market; let us discuss some of the major differences:

• Kotlin has the support of smart cast, which identifies immutable types and performs implicit cast by a compiler, whereas in Java, we need to identify and perform the casting.
• Kotlin has the support of type inference, which means we don’t need to explicitly specify the data type of variable explicitly, whereas, in Java, we need to explicitly specify.
• In Kotlin, we don’t have checked exceptions, which is a disadvantage as it leads to error prone-code, whereas Java has support for checked exceptions by which we can perform error handling.
• Java compilation time is 15-20% faster than Kotlin compilation time, but in the perspective of incremental build compilation, Kotlin will also take the same compilation time as Java.
• In Kotlin, we can’t assign null values to variables or return values; if we really want to assign, then we can declare a variable with a special syntax, whereas in Java, we can assign null values but when we try to access objects pointing to null values raises an exception.
• Kotlin is interchangeable with Java irrespective of the difference between Java vs Kotlin. We can call Kotlin code in Java and Java code in Kotlin. So we can have both Java vs Kotlin classes side by side in a project and compiles without any issues. After compilation, we unable to find which class written in Java or Kotlin.

Java vs Kotlin Comparison Table

Following is the Comparison Table:

The Basis Of Comparison	Java	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 a null value raises a null pointer exception which the 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, 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 Functions	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 with the ability to extend an existing class with new functionality. We can create extend functions by prefixing the name of a class to the 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 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 that 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 that need to hold data, we can declare a class with the 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 them according to our operation.	In Kotlin, smart casts will handle these casting checks with the keyword “is-checks”, which will check for immutable values and performs implicit casting.
Type inference	In Java, we need to specify the type of each variable explicitly while declaring.	In Kotlin, we don’t need to specify the type of each variable explicitly based on the 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.

Conclusion

Finally, its an overview of the comparison  Between Java vs Kotlin. I hope you will better understand these Java vs Kotlin languages after reading this Java vs Kotlin article. In my view, we can proceed with Kotlin for Android application development without worrying about the compilation time even though Java has few advantages over Kotlin.

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