5 Kotlin Features That Everyone Thinks All Android App Developer Must Know

February 02, 2021 Publish By : EXPERT APP DEVS 5 min read Viewed By : 573
Top 5 Kotlin Features

Kotlin may be a brand new artificial language advanced through Jetbrains, the company in the back of one of the major standard Java days, IntelliJ plan. Like Java, Kotlin could be an all-purpose language. Since it complies with the Java Virtual Machine (JVM) bytecode, it's far used side-by-side with Java, and it doesn’t accompany an overall performance overhead.

In this article, I will explain the top five Kotlin programming features for Android development.

 
1) Kotlin Support for Interoperability with Java

 

  • The classes written in Kotlin language can be used in Java and vice versa.so, it will be easy for developers to adopt the best features from java and kotlin.

     For and Example,

  • If we create a Pojo/Model class in Kotlin and use it in Java activity in Android then it will not create an issue.

Kotlin Class:

class UserData {
  var fName: String? = null
  var lName: String? = null
}

Java Activity :

public class MainActivity extends AppCompatActivity {
@Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);

 

UserData data = new UserData();


Log.v("first Name:"+data.fName);

}

}

 

2) Declaring Variables

To define a variable you may use either var or val keywords. In Kotlin you don’t need to explicitly define the data type the variable, you may if you want(in a few locations you may need to define the data type), however the kotlin compiler will automatically infer the data type from the value which you have assigned. 

          Lets see a easy example,

//Defining an int number
var number = 10

 

  • Here we've used the var keyword this means that  the value in the variable number can be changed.
  • If you needed to explicitly define the data type then you definitely could write something like this.    

varnumber: Int = 20

//Defining a string
var name: String = "Example"
var nameImplicit = "Test"

 

  • you don’t have primitive data types in Kotlin, everything in kotlin is an object. So there are no data types like  int or double, there are Int and Double.
  • There are methods to define a variable both via way of means of the usage of var or val, previously we've seen the use of var keyword. The val keyword is quite easy as well, all it means that the variable described is final and the value in it can't be changed, like in java you define immutable variable via way of means of the usage of the keyword final, in addition in Kotlin you'll use the keyword val.

val testString = “AbC”   


// This variable is final, you cannot reassign the value to this variable.


3) Null Safety in Kotlin

 

  • Using this ? operator you can easily avoid null pointer exception in kotlin.

For example :

val value1: Int? = null

  • In the code below the second line will be executed only if the number is not null. For that, You can use the Elvis operator. Which will look like this  (?:)  :

For an example :

val value1: Int? = null
val value1InString = value1?.toString() ?: "value1 is null"

  • With !! operator you are able to throws NullPointerException the same as in Java . Below code will throw a NullPointerException:

For an example :

val value1: Int? = null
value1!!.toString()


 4) Data Classes in Kotlin

It is a most common thing in java to create a POJO class with the setters and getters but with kotlin, all we need to do is just add data keyword before the class and that will become a POJO class in kotlin.in kotlin no need for getter and setter methods, you can directly use their members.

Kotlin Class:

class UserData {
  var fName: String? = null
  var lName: String? = null
}

Java Class:

public class UserDetail {
  private String fName;
  private String lName;
  public String getFName() {
      return fName;
  }
public void setFName(String firstName) {
      this.fName = firstName;
  }
public String getLName() {
      return lName;
  }

  public void setLastName(String lastName) {
      this.lName = lastName;
  }
}

 

5) View Binding in Kotlin

 

  • Do you keep in mind the findViewById() method? We’re certain you don’t like it. We don’t either. Also, we don’t want to declare variables and Butterknife annotations for each view we want to access.
  • No longer do you want to create variables and bind perspectives. You can access your views without delay with their identifiers declared inside the xml layout. 

Java Activity :

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button button1 = (Button) findViewById(R.id.button1);
        final TextView text1 = (TextView) findViewById(R.id.text1);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                text1.setText("You've clicked a button");
            }
        });
    }
}

Kotlin Activity :

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)
        setContentView(R.layout.activity_main)

        button1.setOnClickListener { text1.text = "You've clicked a button" }
    }}

 

Conclusion

Now you may realize why kotlin has more and more popularity in programming. To Conclude, Kotlin offers you the ability to save time for writing android applications compared to java.
 
Benefits of Kotlin : 

  • It’s supported by Android studio excellently.
  • Java and Kotlin code can be used in the same Android project.
  • Very large community for support and contribution.
  • Less code compared to java and less complexity.

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