Part II – Writing Better, Faster and Easy to Maintain Mobile Apps with Realm

In my previous blog post, I described Realm’s seamless synchronization between devices and applications. In this part, we are going to discuss implementation and usage of Realm.

You do not have to create a table, helper etc. in Realm. Just create POJO class, which will be a subclass of RealmObject and you are ready to start using Realm. Here is how to use Realm.

Realm accepts all primitive types and its boxed types (except for char), String, Date and byte[]. It also supports subclasses of RealmObject and RealmList<? extends RealmObject> to model relationships.

Any two RealmObjects can be linked together.

All fetches (including queries) are lazy in Realm, and the data is never copied. Realm’s query engine uses a Fluent interface to construct multi-clause queries.

For all data types, you have the following predicates:

•     equalTo()
•     notEqualTo()

Numeric data types, including Date, allow these additional predicates:

•     between() (Both end points are included, i.e., it is a bounded interval)
•     greaterThan()
•     lessThan()
•     greaterThanOrEqualTo()
•     lessThanOrEqualTo()

String fields allow these additional predicates:

•     contains()
•     beginsWith()
•     endsWith()
•     like()

and one or more wildcards:

•     * matches 0 or more Unicode characters
•     ? matches a single Unicode character

predicates to check for emptiness:

•     isEmpty()
•     isNotEmpty()

Two useful predicates for matching the null value are:

•     isNull()
•     isNotNull()

GSON, Jackson-databind, Kotlin, Parceler, Retrofit, Robolectric, RxJava

This was a quick primer on how to make your mobile apps better, faster and maintainable using Realm.

Also read Introduction to Realm.