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RealmSet - Java SDK
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New in version 10.6.0.
You can use the RealmSet data type
to manage a collection of unique keys. RealmSet implements Java's
Set interface, so it works just like the built-in HashSet class,
except managed RealmSet instances persist their contents to a
realm. RealmSet instances that contain Realm objects
actually only store references to those objects, so deleting a
Realm object from a realm also deletes that object from
any RealmSet instances that contain the object.
Because RealmSet implements RealmCollection, it has some useful
mathematical methods, such as sum, min, and max. For a complete
list of available RealmSet methods, see: the RealmSet API
reference.
Method Limitations
You cannot use the following Realm methods on objects that contain
a field of type RealmSet:
Realm.insert()Realm.insertOrUpdate()Realm.createAllFromJson()Realm.createObjectFromJson()Realm.createOrUpdateAllFromJson()Realm.createOrUpdateObjectFromJson()
Usage
To create a field of type RealmSet, define an object property of
type RealmSet<E>, where E defines the keys you would like to
store in your RealmSet.
Add an object to a
RealmSetwith RealmSet.add()Add multiple objects with RealmSet.addAll()
Check if the set contains a specific object with RealmSet.contains()
Check if the set contains all of multiple objects with RealmSet.containsAll()
Notifications
To subscribe to changes to a RealmSet, pass a
SetChangeListener
implementation to the RealmSet.addChangeListener method.
Your SetChangeListener implementation must define an
onChange() method, which accepts a reference to the changed RealmSet
and a set of changes as parameters. You can access the number of items
added to the set as well as the number of items removed from the set
through the SetChangeSet parameter.