Filter Data - Java SDK

About the Examples on This Page

The examples in this page use two Realm object types: Teacher and Student.

See the schema for these two classes below:

Filters

You can build filters using the operator methods of the fluent interface exposed by the RealmQuery class:

This gives you a new instance of the class RealmResults, containing teachers with the name "Ms. Langtree" or "Mrs. Jacobs".

RealmQuery includes several methods that can execute queries:

• findAll() blocks until it finds all objects that meet the query conditions

• findAllAsync() returns immediately and finds all objects that meet the query conditions asynchronously on a background thread

• findFirst() blocks until it finds the first object that meets the query conditions

• findFirstAsync() returns immediately and finds the first object that meets the query conditions asynchronously on a background thread

Queries return a list of references to the matching Realm objects using the RealmResults type.

Sort Results

You can define the order of query results using the sort() method:

Sorts organize results in ascending order by default. To organize results in descending order, pass Sort.DESCENDING as a second argument. You can resolve sort order ties between identical property values by passing an array of properties instead of a single property: in the event of a tie, Realm Database sorts the tied objects by subsequent properties in order.

Limit Results

You can cap the number of query results to a specific maximum number using the limit() method:

Limited result collections automatically update like any other query result. Consequently, objects might drop out of the collection as underlying data changes.

Unique Results

You can reduce query results to unique values for a given field or fields using the distinct() method:

You can only call distinct() on integer, long, short, and String fields; other field types will throw an exception. As with sorting, you can specify multiple fields to resolve ties.

Chain Queries

You can apply additional filters to a results collection by calling the where() method:

The where() method returns a RealmQuery that you can resolve into a RealmResults using a find method. Filtered results can only return objects of the same type as the original results set, but are otherwise able to use any filters.

Query with Realm Query Language

You can use RealmQuery.rawPredicate() to query realms using Realm Query Language, a string-based query language to constrain searches when retrieving objects from a realm. For more information about syntax, usage and limitations, refer to the Realm Query Language reference.

Realm Query Language can use either the class and property names defined in your Realm Model classes or the internal names defined with @RealmField. You can combine raw predicates with other raw predicates or type-safe predicates created with RealmQuery: