Class MutableRealmInteger

io.realm

Implemented interfaces:

• java.lang.Comparable

A MutableRealmInteger is a mutable, Long -like numeric quantity. It behaves almost exactly as a reference to a Long . More specifically:

• A MutableRealmInteger may have the value null .

• The equals operator compares the contained Long values. null -valued MutableRealmInteger are .equals

• The compareTo operator compares the contained Long values. It considers null < any non-null value.

• The increment and decrement operators throw IllegalStateException when applied to a null -valued MutableRealmInteger .

MutableRealmInteger s are most interesting as members of a managed RealmModel object. When managed, the increment and decrement operators implement a

conflict free replicated data type : Simultaneous increments and decrements from multiple distributed clients will be aggregated correctly. For instance, if the value of counter field for the object representing user "Fred" is currently 0, then the following code, executed on two different devices, simultaneously, even if connected by only a slow, unreliable network, will

always cause the value of counter to converge, eventually on the value 2.

MutableRealmInteger counter = realm.where(Users.class)
   .equalTo("name", Fred)
   .findFirst()
   .counter.increment(1);

Note that the set(Long) operator must be used with extreme care. It will quash the effects of any prior calls to increment(long) or decrement(long) . Although the value of a MutableRealmInteger will always converge across devices, the specific value on which it converges will depend on the actual order in which operations took place. Mixing set(Long) with increment(long) and decrement(long) is, therefore, not advised, unless fuzzy counting is acceptable.

MutableRealmInteger s may not be primary keys. Their implementations are not thread safe. Like all managed Realm objects, managed MutableRealmInteger s may not be moved across threads. Unmanaged MutableRealmInteger s may be moved across threads but require safe publication.

A MutableRealmInteger , in a model class, must always be declared final . For instance:

public final MutableRealmInteger counter = MutableRealmInteger.ofNull();

Although initializing the MutableRealmInteger as null may work very limited circumstances, developers are advised

not to do it:

public final MutableRealmInteger counter = null; // DO NOT DO THIS!

Also note that when a MutableRealmInteger is @Required , it is better, though not required, to initialize it with a non-null value.

@Required public final MutableRealmInteger counter = MutableRealmInteger.valueOf(0L);

A reference to a managed MutableRealmInteger is subject to all of the constraints that apply to the model object from which it was obtained: It can only be mutated within a transaction and it becomes invalid if the Realm backing it is closed. Use the isManaged() and isValid() operators to determine whether a MutableRealmInteger is in a consistent state. Note, in particular, that a reference to a managed MutableRealmInteger retains a reference to the model object to which it belongs. For example in this code:

MutableRealmInteger counter = realm.where(Users.class).findFirst().counter;

the counter holds a reference to the User model object from which it was obtained. Neither can be GCed until all references to both are unreachable.

Method Summary

Inherited Methods

• Methods inherited from class java.lang.Object : getClass , hashCode , equals , clone , toString , notify , notifyAll , wait , wait , wait , finalize

Method Detail