Java was launched in 1995 and developed by James Gosling at Sun Microsystems (which in 2009 was acquired by Oracle). It is an open-source, general-purpose, object-oriented programming language. As a multiplatform language, Java works on almost any device, operating system, and server. In addition, since it is compiled to bytecode, it can run on any Java Virtual Machine (JVM).

Moreover, Java is statically typed, performing type checking during compile time. Java's syntax shares some similarities with C and C++ but provides fewer lower-level facilities.

Kotlin is a much younger language than Java since it was first introduced in 2016. It's an open-source language that can also compile code to bytecode and run on Java Virtual Machine (JVM), enabling it to work on almost any platform. Plus, libraries and frameworks made in Java are also compatible to operate in a Kotlin project.

Inspired by Java, Kotlin aims to express an improved version that is cleaner, simpler, faster to compile, and entails a mix of object-oriented and functional programming.

As mentioned, Java is a general-purpose language, and together with JavaScript and Python, it is among the most popular languages in the world. Kotlin is not yet fighting for that podium, but it has been a tough competitor when it comes to Android development.

One year after its launch, in 2017, Google recognized Kotlin as their second official language for Android development. In 2019, Kotlin was declared as the favored programming language for Android applications at Google. Consequently, this programming language underwent incredible growth.

Now that we have a bit of context, you might wonder how Kotlin's growth impacts Java. Will Kotlin replace it? The answer is not that simple. There are a lot of mixed opinions on this subject. To understand both sides of the debates, let's first take a close look at their differences.

The famous NullPointerExceptions in Java give developers quite a headache. The idea behind NullPointerExceptions is that it enables users to attribute a null value to any variable. Yet, suppose users attempt to use an object reference that happens to have a null value. In that case, Java's NullPointerExceptions comes into play and opens an exception that developers need to handle.

In contrast, in Kotlin, it is not possible to attribute null values to variables or objects by default. If we try to do so, the code will fail at compile time. Therefore, there are no NullPointerExceptions in Kotlin. However, if the developer wishes to assign a null value, it is possible to mark the variable in question as nullable explicitly. To do so, one must add a question mark:

Unlike Java, Kotlin allows the developer to extend the functionality of classes without necessarily having to inherit from a class. To perform the extension function in Kotlin, the developer must prefix the name of the class (that will be extended) to the name of the function created by using the '.' notation.

In Java, to extend the functionality of an existing class, one must create a new class and inherit the functions from the parent class. In other words, the extension function is not available.

One of the key differences between Kotlin and Java is that Kotlin requires way less code. It is a very concise language, which reduces the chances of making code errors and simplifies the developers' work.

Overall, Kotlin's brevity makes it more manageable to write large projects considering that it typically requires fewer lines of code than Java to write the same functions. Plus, it knows how to keep it short and straight to the point without compromising syntax's readability.

In Android, by default, components that belong to the same application run in the same process and thread, typically referred to as the main thread and responsible for the UI. Network I/O and CPU-intensive operations are considered lengthy. When either one of these operations is initiated, the respective calling thread is blocked until the entire operation is completed.

To avoid complications on the main thread, Java enables the creation of multiple background threads when handling lengthy operations. The downside is that managing multiple threads is a complex task that may lead to more errors in the code.

Similarly, Kotlin also provides the capability to create multiple threads. Nonetheless, it introduces a better and more straightforward solution: coroutines.

How do coroutines work? Well, coroutines are stackless and allow the developer to write code, suspend the execution and later resume it again. This enables non-blocking asynchronous code that seems synchronous. Hence, instead of creating multiple threads that the developer must handle later, coroutines avoid having too many threads. Plus, they are clearer and more concise than Java's solution.

On the one hand, in Java, developers need to establish the fields (or variables) to store the data, the constructor, and the getter and setter functions for the fields/variables, as well as other functions, such as the hashCode(), equals(), and toString().

Truth be told, these classes are mainly intended to store data and have zero (or very little, at most) functionality.

On the other hand, Kotlin provides a more straightforward way to create classes to hold data by simply including the "data'' keyword in the class definition. Then the compiler will auto-generate the constructor and the getter and setter functions for several fields/variables.

To cast an object in Java, the developer must check the variables' type in consonance to the operation.

In Kotlin, the casting checks are handled by the smart casts feature. Kotlin's intelligent compiler automatically manages redundant casts (with stable values) via the "is-checks" keyword.

Checked exceptions are not available on Kotlin. Thus, Kotlin's developers do not require to catch or declare exceptions. Is this a good thing? Well, it depends.

Java developers have checked exceptions support. Hence, they must catch and declare exceptions. On the one hand, this can be frustrating and time-consuming. But, on the other hand, it ensures robust code and that errors are being handled. So, checked exceptions support has its pros and cons. Ultimately, it depends on what each developer prioritizes the most.

Functional Programming: Higher-Order Functions and Lambdas

As mentioned at the beginning of the article, Kotlin is a mix of object-oriented and functional programming.

Functional programming is a declarative style of programming that handles computations based on mathematical functions. High-order functions and lambda expressions are (some) functional programming concepts.

The first one indicates that functions should be considered first-class. Thus, Kotlin, a statically typed language, can make the most out of various function types to represent functions. In other words, it is possible to operate functions in a variety of ways.

Furthermore, it is also possible to use lambda expressions or anonymous functions with Kotlin. These are considered a "functional literal". Hence, it represents a function that is not declared and immediately passes as an expression.

Contrarily, Java is more limited to the concept of object-oriented programming. However, it has been taking some steps toward functional programming too. Since Java 8, in 2014, Java has introduced lambda expressions, which is a function that can be created without necessarily belonging to a class. Lambda expressions in Java can be passed as objects and can be executed on demand.

Further, with the introduction of lambda expressions, Java also started supporting high-order functions. Java associates a function with a method, and Java 8 enabled lambda's return from methods.

In Java, variables of a primitive type are not objects; they are predefined Java's data types. Java has eight different primitive data types: int, byte, short, double, float, boolean, char, and long. Consequently, these variables cannot be an object represented from a struct or a class.

Even though primitive types are not classes, Java developers can use classes that can wrap a value of the primitive type. To do so using Java, the developer must indicate it explicitly.

In contrast, in Kotlin, as soon as you initiate a variable of a primitive type, it will be automatically considered an object.

Public fields (also known as non-private fields) are available in Java. They can be pretty convenient in case the callers of an object require to modify according to the representation of that same object since it enables the developer to change the representation of an object without needing to adjust the callers. This way, the fields can be public; thus, the public API remains unchanged, and the program can sustain a level of maintainability.

In contrast, Kotlin does not have public fields.

Typically, a question mark (?) in code is considered a wildcard, which suggests an unknown type (of variable, field, or parameter).

Unlike Java, Kotlin does not provide wildcards. Instead, it has a declaration-site variance and type projections, which serve as an alternative.

On the one hand, Kotlin does not provide support for implicit widening conversions. Therefore, smaller types cannot be converted to bigger types. To overcome this, Kotlin developers must execute an explicit conversion to achieve the desired type conversion.

On the other hand, Java supports implicit conversions, meaning the developers do not need to perform explicit conversions.

Now we will discuss in this blog Difference Between Kotlin and Java.

Difference Between Kotlin and Java 

Kotlin is a statically-typed programming language that runs on the Java Virtual Machine (JVM) and was developed by JetBrains in 2011. Kotlin was designed to address some of the shortcomings of Java and provide a more modern, concise, and expressive language for building applications. Kotlin is fully interoperable with Java, which means that you can use Kotlin code in a Java project and vice versa.

Java is a high-level, object-oriented programming language that was developed by Sun Microsystems (now owned by Oracle) in 1995. Java has become one of the most popular programming languages in the world and is widely used for building enterprise applications, mobile apps, and web applications. Java is also used as the primary language for developing Android applications.

While both Kotlin and Java run on the JVM and are used for similar purposes, Kotlin offers several advantages over Java, such as null safety, functional programming features, extension functions, and better support for coroutines. Kotlin also has a more concise and expressive syntax compared to Java, which can lead to more efficient and maintainable code.

There are some significant differences between the two are given below:

1. Syntax: Kotlin has a more concise and expressive syntax compared to Java. It uses fewer lines of code to accomplish the same tasks, and it has a simpler and more intuitive syntax.

2. Null safety: Kotlin has built-in null safety features, which means that the compiler can catch potential null pointer exceptions at compile-time rather than at runtime. Java, on the other hand, does not have built-in null safety features.

3. Interoperability: Kotlin is fully interoperable with Java, which means that you can use Kotlin code in a Java project and vice versa. However, Java does not have full interoperability with Kotlin.

4. Functional programming: Kotlin has better support for functional programming compared to Java. It has higher-order functions, lambdas, and other functional programming features built-in, while Java requires more boilerplate code to achieve the same functionality.

5. Extension functions: Kotlin has extension functions, which allow you to add new functions to existing classes without having to subclass or modify the original class. Java does not have this feature.

6. Data classes: Kotlin has built-in support for data classes, which are classes that are designed to hold data rather than behavior. Data classes are automatically generated with a toString() method, equals() and hashCode() methods, and a copy() method. Java does not have this feature.

7. Coroutines: Kotlin has built-in support for coroutines, which allow for asynchronous programming with ease. Coroutines make it possible to write asynchronous code in a more sequential, synchronous style. Java has support for asynchronous programming with libraries like CompletableFuture, but it requires more boilerplate code to achieve the same functionality.

8. Properties: Kotlin has a concise syntax for creating properties with getters and setters, while Java requires you to write separate getter and setter methods.

9. Smart casts: Kotlin has smart casts, which allow the compiler to automatically cast an object to a specific type when it is safe to do so. Java does not have this feature.

10. Type inference: Kotlin has better support for type inference, which means that you can often omit the type declaration of a variable or function parameter, and the compiler will infer the type based on the context. Java requires you to declare the type of every variable and function parameter.

11. Ranges: Kotlin has built-in support for ranges, which allow you to create a range of values with a start and end point. This makes it easy to iterate over a range of values, or check if a value falls within a certain range. Java does not have this feature.

12. Operator overloading: Kotlin allows you to overload operators like +, -, *, /, and others for your own classes, making it possible to write more expressive and concise code. Java does not have this feature.

13. Multiple inheritance: Kotlin does not support multiple inheritance, which means that a class can only inherit from one parent class. Java also does not support multiple inheritance, but it has interfaces that can be used to achieve similar functionality.

14. Inline functions: Kotlin has the ability to declare inline functions, which can improve performance by reducing function call overhead. Java does not have this feature.

15. Default parameter values: Kotlin allows you to specify default parameter values for functions, which can make it easier to call functions with fewer arguments. Java does not have this feature.

16. String templates: Kotlin has a feature called string templates, which allows you to embed expressions inside strings without concatenating them. Java requires you to use string concatenation to achieve the same functionality.

Overall, Kotlin and Java are both great languages, and the choice between the two depends on the specific requirements of the project. Kotlin is a more modern and concise language with better support for functional programming and null safety, while Java has a large developer community, a rich ecosystem of libraries and tools, and is more established in enterprise applications.

Both Kotlin and Java run on the JVM and are used for similar purposes, Kotlin offers several advantages over Java, so let's go to know what are the differences between them.

kotlin vs java

Trending Blogposts on kotlin vs java

Difference Between Kotlin and Java

Kotlin vs Java: What Are the Differences between them?

Popular Discussions on kotlin vs java

PRODUCTS

QUICK LINKS

LEGAL

kotlin vs java

Trending Blogposts on kotlin vs java

Difference Between Kotlin and Java

Kotlin vs Java: What Are the Differences between them?

Popular Discussions on kotlin vs java