FirebaseDatabase

Also: Google Play services

public class FirebaseDatabase extends Object

The entry point for accessing a Firebase Database. You can get an instance by calling getInstance(). To access a location in the database and read or write data, use getReference().

Public Method Summary

FirebaseApp	getApp() Returns the FirebaseApp instance to which this FirebaseDatabase belongs.
static FirebaseDatabase	getInstance(String url) Gets a FirebaseDatabase instance for the specified URL.
static FirebaseDatabase	getInstance() Gets the default FirebaseDatabase instance.
static FirebaseDatabase	getInstance(FirebaseApp app) Gets an instance of FirebaseDatabase for a specific FirebaseApp.
synchronized static FirebaseDatabase	getInstance(FirebaseApp app, String url) Gets a FirebaseDatabase instance for the specified URL, using the specified FirebaseApp.
DatabaseReference	getReference() Gets a DatabaseReference for the database root node.
DatabaseReference	getReference(String path) Gets a DatabaseReference for the provided path.
DatabaseReference	getReferenceFromUrl(String url) Gets a DatabaseReference for the provided URL.
static String	getSdkVersion()
void	goOffline() Shuts down our connection to the Firebase Database backend until goOnline() is called.
void	goOnline() Resumes our connection to the Firebase Database backend after a previous goOffline() call.
void	purgeOutstandingWrites() The Firebase Database client automatically queues writes and sends them to the server at the earliest opportunity, depending on network connectivity.
synchronized void	setLogLevel(Logger.Level logLevel) By default, this is set to INFO.
synchronized void	setPersistenceCacheSizeBytes(long cacheSizeInBytes) By default Firebase Database will use up to 10MB of disk space to cache data.
synchronized void	setPersistenceEnabled(boolean isEnabled) The Firebase Database client will cache synchronized data and keep track of all writes you've initiated while your application is running.

Inherited Method Summary

From class java.lang.Object

Object	clone()
boolean	equals(Object arg0)
void	finalize()
final Class<?>	getClass()
int	hashCode()
final void	notify()
final void	notifyAll()
String	toString()
final void	wait(long arg0, int arg1)
final void	wait(long arg0)
final void	wait()

Public Methods

public FirebaseApp getApp ()

Also: Google Play services

Returns the FirebaseApp instance to which this FirebaseDatabase belongs.

Returns

• The FirebaseApp instance to which this FirebaseDatabase belongs.

public static FirebaseDatabase getInstance (String url)

Also: Google Play services

Gets a FirebaseDatabase instance for the specified URL.

Parameters

url	The URL to the Firebase Database instance you want to access.

Returns

• A FirebaseDatabase instance.

public static FirebaseDatabase getInstance ()

Also: Google Play services

Gets the default FirebaseDatabase instance.

Returns

• A FirebaseDatabase instance.

public static FirebaseDatabase getInstance (FirebaseApp app)

Also: Google Play services

Gets an instance of FirebaseDatabase for a specific FirebaseApp.

Parameters

app	The FirebaseApp to get a FirebaseDatabase for.

Returns

• A FirebaseDatabase instance.

public static synchronized FirebaseDatabase getInstance (FirebaseApp app, String url)

Also: Google Play services

Gets a FirebaseDatabase instance for the specified URL, using the specified FirebaseApp.

Parameters

app	The FirebaseApp to get a FirebaseDatabase for.
url	The URL to the Firebase Database instance you want to access.

Returns

• A FirebaseDatabase instance.

public DatabaseReference getReference ()

Also: Google Play services

Gets a DatabaseReference for the database root node.

Returns

• A DatabaseReference pointing to the root node.

public DatabaseReference getReference (String path)

Also: Google Play services

Gets a DatabaseReference for the provided path.

Parameters

path	Path to a location in your FirebaseDatabase.

Returns

• A DatabaseReference pointing to the specified path.

public DatabaseReference getReferenceFromUrl (String url)

Also: Google Play services

Gets a DatabaseReference for the provided URL. The URL must be a URL to a path within this FirebaseDatabase. To create a DatabaseReference to a different database, create a FirebaseApp with a FirebaseOptions object configured with the appropriate database URL.

Parameters

url	A URL to a path within your database.

Returns

• A DatabaseReference for the provided URL.

public static String getSdkVersion ()

Also: Google Play services

Returns

• The semver version for this build of the Firebase Database client

public void goOffline ()

Also: Google Play services

Shuts down our connection to the Firebase Database backend until goOnline() is called.

public void goOnline ()

Also: Google Play services

Resumes our connection to the Firebase Database backend after a previous goOffline() call.

public void purgeOutstandingWrites ()

Also: Google Play services

The Firebase Database client automatically queues writes and sends them to the server at the earliest opportunity, depending on network connectivity. In some cases (e.g. offline usage) there may be a large number of writes waiting to be sent. Calling this method will purge all outstanding writes so they are abandoned.

All writes will be purged, including transactions and onDisconnect() writes. The writes will be rolled back locally, perhaps triggering events for affected event listeners, and the client will not (re-)send them to the Firebase backend.

public synchronized void setLogLevel (Logger.Level logLevel)

Also: Google Play services

By default, this is set to INFO. This includes any internal errors (ERROR) and any security debug messages (INFO) that the client receives. Set to DEBUG to turn on the diagnostic logging, and NONE to disable all logging.

Parameters

logLevel	The desired minimum log level

public synchronized void setPersistenceCacheSizeBytes (long cacheSizeInBytes)

Also: Google Play services

By default Firebase Database will use up to 10MB of disk space to cache data. If the cache grows beyond this size, Firebase Database will start removing data that hasn't been recently used. If you find that your application caches too little or too much data, call this method to change the cache size. This method must be called before creating your first Database reference and only needs to be called once per application.

Note that the specified cache size is only an approximation and the size on disk may temporarily exceed it at times. Cache sizes smaller than 1 MB or greater than 100 MB are not supported.

Parameters

cacheSizeInBytes	The new size of the cache in bytes.

public synchronized void setPersistenceEnabled (boolean isEnabled)

Also: Google Play services

The Firebase Database client will cache synchronized data and keep track of all writes you've initiated while your application is running. It seamlessly handles intermittent network connections and re-sends write operations when the network connection is restored.

However by default your write operations and cached data are only stored in-memory and will be lost when your app restarts. By setting this value to `true`, the data will be persisted to on-device (disk) storage and will thus be available again when the app is restarted (even when there is no network connectivity at that time). Note that this method must be called before creating your first Database reference and only needs to be called once per application.

Parameters

isEnabled	Set to true to enable disk persistence, set to false to disable it.