17 Killer Tips for Developing Android Apps Using Kotlin

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Kotlin was released around 2016, and its plugin was incorporated into version 3.0 of Android Studio. At the time of its release, a lot of people were skeptical about its benefits, like Savvy Apps, but many decided to give it a trial on a smaller project scale. The talking point of Kotlin is its ease of use.

While using Kotlin programming language, you will be able to separate business logic and functionality using extensions. It also saves you a lot of developing hours. These benefits have made many programmers employ Kotlin as their first-choice programming language for Android app creation.

If you are using an earlier version of Android Studio, you can still install the Kotlin plugin as follows: Go to File > Settings > Plugins, where you will find the JetBrains plugin. Install it and then search for Kotlin and install that as well. After the installation is complete, you will need to restart the IDE. If you are looking for some programming jobs that will help you practice the use of Kotlin, you are welcome to browse Freelancer.com for hundreds of them.

Kotlin was developed by JetBrains and runs smoothly on IntelliJ and Android Studio. After a successful installation, you will have two options: either to create a new Android project or to add an existing Android project. The following Kotlin tips will be invaluable to anyone using this programming language for Android app development. To enjoy the full benefits of these tips, you should already be familiar with Android SDK.

1. Lazy-Load Feature

Lazy loading has several benefits, including faster start-up time. This is because variables will load only when they are accessed, and it gives Kotlin an edge. The target of Android app developers is usually to reduce startup time, so users can access its content faster. The selective loading of resources is more memory-efficient too.

2. Create a New Project

Starting a new project on Kotlin is easy; go to File and select New Project. Next, you will need to name the new project and then select the installed Android SDK version. Leave most of the options on default by pressing Enter as they show up.

3. Custom Getters and Setters

Custom getters and setters on Kotlin use a model structure, but behaviors to get and set the fields are specified. Non-class local variables, stored and retrieved in some custom way like from JSON, occur when custom models for some frameworks such as Parse SDK are used. The values would look much like what is obtainable using other model’s access syntax. Changing your model from Parse to another data source may only require a small alteration to your code.

4. Convert Java Code to Kotlin

There are several ways you can do this. One of them is by opening the MainActivity.java file and then selecting “Convert java file to Kotlin file”. The easiest way to go about this is to search for the action. It can also be accomplished using shortcuts which can be found at the menu entry.

5. Use of Lambdas

The overall lines of codes in a source file can be reduced using lambdas which give room for more functional programming. Lambdas are possible with Android, and the build configuration will remain unaltered. Kotlin ensures you won’t have to deal with Retrolambda. Lambda works wonders when you are implementing a single method, or setting a listener for an Android SDK with plenty of cases.

6. Applying filter to collections

When working with API, you will deal with a number of collections. Many times, you will want to modify or just filter the collection contents. Kotlin collection filtering can help you to achieve this, giving clarity to your code to make it more concise. A filter will help you to predict what your new list will contain. Collection filtering is very helpful when you are working with a team.

7. Simplifying data using Data Classes

Classes are simplified with data classes, with a few methods automatically added including hash code (), equals (), to String (), and copy (). Data classes clarify a model’s intention and what should be in it, further separating business logic from pure data.

8. Null Safety

This is by far one of the biggest features of Kotlin. The aim of null safety is to rid your app of null references danger. This is determined by a type system which can differentiate between nullable references and non-null references. This is especially important when your references are to be null, so you don’t run into null pointer exceptions (NPE).

9. Object Expressions

Strict singleton definition is allowed by object expressions. This is relevant so they will not be mistaken for a class that can be exemplified. This means you will not run into the problem of scrambling for where the static instance is stored or affirming a constructor as private.

10. Global Constants

Where it is applicable, constants that span the entire app can be defined in one place using Kotlin. The scope of constants should be reduced as much as possible to avoid complexity, but for instances where the scope will need to be global, going through Kotlin is a great way to go about it without having to take the long route of constants class.

11. Companion Object

At first look, it may seem as if Kotlin has missed static variables and methods. That idea has been replaced by companion objects, singleton objects enabling the methods and variables within a class. It allows defined methods and constants as you will find in Java, and gives you access to the newInstance fragment pattern.

12. Optional Parameters

If you don’t want to pass through default value or null, optional parameters are a good option to add flexibility to your method calls. When defining animations, you will find this option invaluable.

13. Latinit

Non-null properties can be initialized using latinit in Kotlin. This is generally geared towards null safety. It allows you to handle methods as if they are not null with a familiar syntax. It may take you some time to get used to this feature. The!! Operators can be removed which makes the code cleaner, as David Vavra has extensively explained.

14. Extensions

You can add the functionality of a class without necessarily inheriting it using extensions. The readability of a code can be enhanced using extensions, because you can easily take out utility classes or methods.

15. Let

Null checks can be avoided when you let. If a value of an object is not null, let will permit you to execute it as a block. Besides the reader-friendly nature, users will automatically be assigned to an un-nullable variable by let. This allays the fear of being nulled out.

16. Safe Typecasting

Normal typecasting in some Android conventions will cause an exception. In such instances, a safe typecasting would be required. Typically, to create a Fragment in an Activity, you have to first run a check to see if it already exists using Fragment Manager. If it doesn’t, you can then create it and add it to the Activity.

17. Easier validation

In the course of developing an Android app, you will be required to make validations. Those who have dealt with this when using other programming languages will be familiar with the TextUtils class. However, Kotlin has a built-in isNullorBlank and isNullorEmpty to erase the need for TextUtils.isEmpty(someString). There is the added benefit of checking for whitespace alone.

Kotlin advanced tips

The major benefits of working with Kotlin are its simplicity, and a cleaner working platform. For example, Single Abstract Method (SAM) conversions can be performed for Java classes using a reduced syntax.

Kotlin may be a little confusing for new users, but with a bit of practice you’ll soon be able to find your way around. You will also get a warning to proofread after the conversion, which is great to avoid producing ambiguous codes. Knowing these tips should give you a head start to using Kotlin to handle your Android projects. You can learn more from Kotlin’s documentation.

Have you already used Kotlin? Let us know in the comments below 


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Posted 6 August, 2017


Software Developer

Lucy is the Development & Programming Correspondent for Freelancer.com. She is currently based in Sydney.

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