MainActivity.kt

package com.example.realmqueryplayground

import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import io.realm.Realm
import io.realm.RealmConfiguration
import junit.framework.Assert.assertTrue
import java.util.*

class MainActivity : AppCompatActivity() {

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

    private fun compareQueries() {
        val results1 = mutableListOf<TestData>()
        val results2 = mutableListOf<TestData>()
        doOnRealm {
            executeTransaction { transactionRealm ->
                results2.addAll(transactionRealm.where(TestData::class.java)
                    .beginGroup()
                    .equalTo("name", "Bob")
                    .beginGroup()
                    .lessThan("count", 3).or().greaterThan("count", 5)
                    .endGroup()
                    .endGroup()
                    .or().equalTo("active", true)
                    .findAll()
                    .map { TestData(it.name, it.count, it.active) })
            }
        }
        doOnRealm {
            executeTransaction { transactionRealm ->
                results1.addAll(transactionRealm.where(TestData::class.java)
                    .beginGroup()
                    .beginGroup()
                    .lessThan("count", 3).or().greaterThan("count", 5)
                    .endGroup()
                    .equalTo("name", "Bob")
                    .endGroup()
                    .or().equalTo("active", true)
                    .findAll()
                    .map { TestData(it.name, it.count, it.active) })
            }
        }

        assertTrue(results1.size == results2.size)
    }

    private fun initRealm() {
        Realm.init(this)
        val realmConfiguration = RealmConfiguration.Builder()
            .name(Realm.DEFAULT_REALM_NAME)
            .deleteRealmIfMigrationNeeded()
            .build()
        Realm.deleteRealm(realmConfiguration)
        Realm.setDefaultConfiguration(realmConfiguration)
        val names = arrayOf("Bruce", "Peter", "Bob", "Greg", "Ivan", "John", "Antony")
        val random = Random()
        val testData = (0..99)
            .map {
                TestData(
                    names[random.nextInt(names.size)],
                    random.nextInt(7),
                    random.nextBoolean()
                )
            }

        doOnRealm {
            executeTransaction { transactionRealm -> transactionRealm.copyToRealm(testData) }
        }
    }

    private inline fun doOnRealm(action: Realm.() -> Unit) {
        var realm: Realm? = null
        try {
            realm = Realm.getDefaultInstance()
            realm.action()
        } finally {
            try {
                realm?.close()
            } catch (throwable: Throwable) {
                //ignore
            }
        }
    }
}