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Hackernoon logoKotlin Vs Java : What's The Best Choice for Mobile App Development? by@manojrupareliya

Kotlin Vs Java : What's The Best Choice for Mobile App Development?

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@manojrupareliyaManoj Rupareliya

Manoj Rupareliya is a Online Marketing Consultant and blogger.

Have a great idea for your mobile app development? Then it's the right time to bring into action by searching for the right technology for your app development. And when it comes to mobile and web app development, then most of the businesses look forward to choosing the most affordable and effective option for their project development.

And one of the biggest confusion they face is when it comes to making a choice between Kotlin and Java as the programming language.

Java is one of the well-tested technologies which has been used by developers and users for a long duration of time, while Kotlin is completely new in the development market.

Also, Kotlin has gained huge popularity among users at an unprecedented rate. Google, during 2017 has declared Kotlin as the second official language for app development. Between 2019 and 2020, Kotlin has become the mainstream for Android app development.

Kotlin Vs. Java: Explore to Know Which is Best Option for Android App Development

A programming language can simply be termed as a formal language that users use to produce various kinds of outputs, they can make use of a particular set of instructions to craft the best project. The end number of programming languages is discovered, which can be used when it comes to developing an advanced and feature-rich solution.

Image: (Source)

Some of the programming languages are coded in an imperative form, this imperative programming language follows a sequence of operations that can be proven to be beneficial, especially when it comes to generating output, while other programming languages use a declarative form. When it comes to a declarative programming language, then there is the desired output which is specified, but at the same time, methods need to be obtained.

Numerous programming languages such as C, Swift, Java, Python, Go, Dart, and many other languages are widely used by app developers. When we talk about the Android programming language, then Kotlin is one of the most demanded languages compared to Java. Explore to know why most of the developers opt for Kotlin instead of Java when it comes to Android app development.

Explore to Know Difference Between Java and Kotlin Program

There is a minor difference, which is shown in two programs that are written using Java and Kotlin programming language, knowing how the Java program actually looks when it is translated to Kotlin.

Code for Simple Java Program:

public class JavaCode {
	public String toJSON(Collection<Integer> collection) {
    	StringBuilder sb = new StringBuilder();
    	Iterator<Integer> iterator = collection.iterator();
    	while (iterator.hasNext()) {
        	Integer element =;
        	if (iterator.hasNext()) {
            	sb.append(", ");
    	return sb.toString();

Translated Code From Java to Kotlin:

fun toJSON(collection: Collection<Int>): String {
	val sb = StringBuilder()
	val iterator = collection.iterator()
	while (iterator.hasNext())
    	val element =
    	if (iterator.hasNext())
        	sb.append(", ")
	return sb.toString()

Kotlin as a More Concise Programming Language

At first glance, Kotlin can be considered as a streamlined and concise version of Java. Consider the above-given code, where we have translated a simple Java code sample to Kotlin. Explore the inherent which are repeating and the instantiation Java variables have removed. Also, notice the Java idiom.

StringBuilder sb = new StringBuilder();

Has translated and has become:

val sb = StringBuilder()

In the same code, you can also identify that the fun keyword and that semicolon have become optional when new lines are being coded. The val keyword in the code declares a local variable. Similarly, the var keyword in the same code identified mutable property. There is no doubt that Kotlin is typed much stronger than any of the programming languages. var and val keywords can only be used when inferred are considered as the type. Else developers have to declare the type when they use the solution, inference type is improving with each new release of Kotlin.

Functional Programming Using Kotlin

Kotlin provides users with top-level functions, but this is just the beginning story. The widely used language also supports anonymous and higher-order functions, besides this, it also provides support to closures, lambdas, tail recursion, generics, inline functions, and much more. In simple words, we can say that Kotlin possesses all the advanced features and provide users with numerous benefits of a functional language. For instance, consider the following functions of Kotlin:

Function for filtering a list in Kotlin:

val positives = list.filter { x -> x > 0 }

When it comes using for a shorter expression, that is when there is a single parameter in the lambda function, then use the following function:

val positives = list.filter { it > 0 }

Function for traversing a map using Kotlin programming language:

for ((k, v) in map) { println(โ€œ$k -> $vโ€) }

k and v can be termed as anything in the program as per the developers' requirement.

Effective Ways to Use Ranges in Kotlin

for (i in 1..100) { ... }ย  // closed range: includes 100
for (i in 1 until 100) { ... } // half-open range: does not include 100
for (x in 2..10 step 2) { ... }
for (x in 10 downTo 1) { ... }
if (x in 1..10) { ... }

The above examples simply represent the use of ranges and also identifies the keyword.

Everyone who is familiar and making use of Kotlin knows it well that it is a full-fledged functional programming language, this popular programing language also poses the object-oriented nature of Java, it poses all the capabilities of this programming language as an alternative programming style, which is very helpful when it comes to converting existing Java code.

Kotlin enables users to use various classes such as constructors, nested, anonymous inner classes, and inner, besides this, it also allows them to interfaces which they are offered to use in Java 8. Kotlin has a single inheritance which is identified as a superclass, and also understands that there is one superclass for every class in Kotlin. Thus is quite the same as Java base class java.lang.Object. This programming language only contains three predefined member functions, these functions include:

  • equals().
  • hashCode().
  • toString().

The availability of numerous classes and functions makes it quite easy for developers when it comes to developing an advanced solution. They can leverage the use of class and inheritance while crafting an android app solution using Kotlin as a programming language.

Safety Features Kotlin Offers to Developers

When it comes to avoiding common errors, then Kotlin can prove to be the best option, this programming language has been launched to eliminate all the issues of a null pointer. It becomes quite easy for developers to handle all the null values when they consider developing the project by making use of Kotlin. This language enables this by making the null value illegal for standard types, it also allows adding nullable types. Any of the users who uses this programming language can consider implementing shortcut notations, which helps them to handle tests for null.

Let's explain you this short example, we have considered here a regular variable of String type which can't hold null value ever:

var a: String = "ABC"
a = null // compilation error

If you want that this value must allow nulls, for instance, if you want that it must hold SQL query results, then it becomes vital for you to declare the same as a type nullable by appending a question mark sign to the String type, for example, String?.

var b: String? ="abc"
b = null // ok

The protections can be shifted a little further as you can easily use a type non-nullable with impunity, but it becomes vital for you to test a type nullable for null values before making the use of the same.

To avoid verbose grammar, which is required for null testing normally, Kotlin enables a safe and secure call, which is identified as ?. For example, b?.length identified the b.length if b is null, or not null, the type can otherwise be written as Int?.

In simple words, we can say that b?.length is a shortcut for writing if

(b != null)
b.length else null. Thus it can be said that this syntax chain helps in eliminating a lot of prolix logic very wisely, which results in decreasing code to a great extent. This can prove to be more beneficial, especially when an object was populated from database queries. For instance, the department? or head? or name? or any other series of fields available in the database. This will allow you to keep the null value in any of the fields you desire.

If you aim to perform certain operations for non-null values, then it will be better for you to call an operator ?. with let, explore the coding for performing the same task.

val listWithNulls: List<String?> = listOf("Kotlin Language", null)
for (item in listWithNulls Value) {
	item?.let { println(it) } // else prints A and ignores null

Most of us return a valid while considering a special value from a nullable expression, this can help us to save the value into a type non-nullable. This can be considered as one of the special syntaxes for calling Elvis operator, which can be written as ?:.

val l = b?.length ?: -1
is the equivalent of
val l: Int = if (b != null) b.length else -1

In the same way, Kotlin also eliminates some of Javaโ€™s checked exceptions, this elimination includes throwable conditions which must be caught while executing the program. For example, the JDK signature.

Appendable append(CharSequence cs) throws IOException;

You require it every time to catch an IOException when you make a call for the append method, explore the below code to know how it actually works.

try {
ย ย log.append(message)
catch (IOException e) {
ย ย // Do something with the exception

All Code: (Source)

Using Kotlin instead of Java is the best choice as it helps programmers to develop advanced applications as well as a website that meets the demand of all the people in a much better way. This makes it simple for them to implement sensible data in the catch clause, which was carried out when writing a large Java program, however, you can explore some of the code above where the catchy calling clause becomes a mandatory part. This might help you to work with large programs much easier and also avoid losing data, which is very important for the program.

Summing It Up

Nevertheless, Kotlin is a completely new language in the development market compared to Java, but then also it has made its special place in the market. Kotlin is proving its worth in the development space at great speed and proved itself as a superior programming language when it comes to mobile app development. This advanced programming language provides developers with numerous scope and opportunities to go ahead with the modern programming language. It also allows developers to make the essential transitions between scripting, declarative paradigms, OO, and FP that also without making many efforts for establishing a new programming standard.


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