How to use Realm DB in Android Studio - Part 1 - Adding Dependencies

 1. Apply this on project level build.gradle

  buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath "io.realm:realm-gradle-plugin:6.0.2"
    }
  }

 2. Apply this on app level build.gradle on very top.

  apply plugin: 'com.android.application'
  apply plugin: 'kotlin-kapt'
  apply plugin: 'kotlin-android'
  apply plugin: 'kotlin-android-extensions'
  apply plugin: 'realm-android'

 3. Create a model Person.kt

  import io.realm.RealmObject
  import io.realm.annotations.PrimaryKey

  open class Person(
      // Properties can be annotated with PrimaryKey or Index.
      @PrimaryKey var id: Long = 0,
      var name: String = "",
      var age: Int = 0,

      // Other objects in a one-to-one relation must also subclass RealmObject.
  ): RealmObject()
  

 4. Create a class which extends Application class. Name it MyApplication.kt

    import android.app.Application
    import io.realm.Realm

    class MyApplication : Application() {

        override fun onCreate() {
            super.onCreate()
            // Initialize Realm. Should only be done once when the application starts.
            Realm.init(this)
        }
    }

 5. Now take an instance of your Realm object and use in your activity.For example MainActivity.java

    import android.os.Bundle
    import android.util.Log
    import androidx.appcompat.app.AppCompatActivity
    import com.blogspot.quizappmba.model.Person
    import io.realm.Realm
    import io.realm.kotlin.createObject
    import io.realm.kotlin.where

    class MainActivity : AppCompatActivity() {
        companion object {
            const val TAG: String = "KotlinExampleActivity"
        }

        private lateinit var realm: Realm

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

            realm = Realm.getDefaultInstance()

            // All writes must be wrapped in a transaction to facilitate safe multi threading
            realm.executeTransaction { realm ->
                // Add a person
                val person: Person = realm.createObject(0)
                person.name = "Young Person"
                person.age = 14
            }

            // Find the first person (no query conditions) and read a field
            val person = realm.where<Person>().findFirst()!!
            Log.i(TAG, "onCreate: " + person.name)
        }


    }

 Output : I/KotlinExampleActivity: onCreate: Young Person