| Java vs Kotlin |
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 null value raises a null pointer exception which user needs to handle. |
In Kotlin, By default, all types of variables are non-null able (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 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. |
VietMX Staff asked 4 years ago
