Cannot set up Realm in project using Kotlin

Question

I'm trying to build a test project in Kotlin with Realm. Here's my model:

open class Book : RealmObject() {

    // Standard getters & setters generated by your IDE…
    @PrimaryKey
    open var id: Long = 0

    open var title = ""

    open var description = ""

    open var author = ""

    open var imageUrl = ""
}

and here's exception I get:

FATAL EXCEPTION: main
                                                                        Process: app.androidhive.info.realm, PID: 18782
                                                                        java.lang.RuntimeException: Unable to start activity ComponentInfo{app.androidhive.info.realm/app.androidhive.info.realm.activity.MainActivity}: java.lang.IllegalArgumentException: Book is not part of the schema for this Realm
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                            at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                            at android.os.Looper.loop(Looper.java:148)
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                            at java.lang.reflect.Method.invoke(Native Method)
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                         Caused by: java.lang.IllegalArgumentException: Book is not part of the schema for this Realm

I searched around for the solution so and added classpath "io.realm:realm-gradle-plugin:2.2.2" in build.gradle and apply plugin: 'realm-android' and

dependencies {
    ...
    // Realm
    compile 'io.realm:realm-android:0.87.4'
    kapt "io.realm:realm-annotations:0.87.4"
    kapt "io.realm:realm-annotations-processor:0.87.4"
}

into build script in module app. It gives me another problem:

Error:(15, 48) Cannot access '<init>': it is public/*package*/ in 

'Builder'
/Volumes/Toshiba/Users/macuser/Development/Android/Exersises/MyApplication/app/src/main/java/realmtest/realm/RealmController.kt
Error:(27, 15) Unresolved reference: refresh
Error:(34, 15) Unresolved reference: clear
Error:(53, 23) Unresolved reference: allObjects

[KOTLIN] deleting /Volumes/Toshiba/Users/macuser/Development/Android/Exersises/MyApplication/app/build/tmp/kotlin-classes/debug on error

I can only build my project successfully if Book is written in java. Any suggestion how to make Realm and Kotlin work together?

Answer 1

Use RealmClass annotation + RealmModel interface

import io.realm.Realm
import io.realm.RealmModel
import io.realm.annotations.PrimaryKey
import io.realm.annotations.RealmClass

@RealmClass
open class Example(
    @PrimaryKey open var Id : Long = 0,
    open var Field : String = ""
) : RealmModel

In module gradle file add

apply plugin: 'realm-android'

In project gradle file add

classpath "io.realm:realm-gradle-plugin:2.2.2"

No additional compile/kapt needed