Connect to a MongoDB Realm Backend App - Java SDK
The Realm app client is the interface to the MongoDB Realm backend. It provides access to the authentication functionality, functions, and sync management.
Initialize Realm
Before you can use Realm in your app, you must initialize the Realm library. Your application should initialize Realm just once each time the application runs.
To initialize the Realm library, provide an Android
context
to the Realm.init()
static function. You can provide
an Activity, Fragment, or Application context
for initialization with no
difference in behavior. You can initialize the Realm library
in the onCreate()
method of an application subclass to
ensure that you only initialize Realm once each time the
application runs.
If you create your own Application
subclass, you must add it to your
application's AndroidManifest.xml
to execute your custom
application code. Set the android.name
property of your manifest's
application definition to ensure that Android instantiates your Application
subclass before any other class when a user launches your application.
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.mongodb.example"> <application android:name=".MyApplicationSubclass" ... /> </manifest>
Access the App Client
Pass the Realm app ID for your Realm app, which you can find in the Realm UI.
You must initialize your Realm app connection with
Realm.init()
before creating any instance of an App
.
You can create multiple App
instances to connect to multiple
Realm apps or to the same Realm app with different configurations. All
App
instances that share the same App ID use the same underlying
connection.
Configuration
For more granular control of the details of your app connection,
such as custom timeouts for connections, codecs used for MongoDB Data Access,
and keys for local encryption, you can use the AppConfiguration
Builder to control details of your App
:
For most use cases, you only need your application's App ID to connect to MongoDB Realm. The other settings demonstrated here are optional.