Query

public class Query extends Object

Known Direct Subclasses

DatabaseReference

The Query class (and its subclass, DatabaseReference) are used for reading data. Listeners are attached, and they will be triggered when the corresponding data changes.

Instances of Query are obtained by calling startAt(), endAt(), or limit() on a DatabaseReference.

Public Method Summary

ChildEventListener	addChildEventListener(ChildEventListener listener) Add a listener for child events occurring at this location.
void	addListenerForSingleValueEvent(ValueEventListener listener) Add a listener for a single change in the data at this location.
ValueEventListener	addValueEventListener(ValueEventListener listener) Add a listener for changes in the data at this location.
Query	endAt(String value, String key) Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key key less than or equal to the given key.
Query	endAt(String value) Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default.
Query	endAt(double value, String key) Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key less than or equal to the given key.
Query	endAt(double value) Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default.
Query	endAt(boolean value) Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default.
Query	endAt(boolean value, String key) Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key less than or equal to the given key.
Query	equalTo(String value, String key) Create a query constrained to only return the child node with the given key and value.
Query	equalTo(double value) Create a query constrained to only return child nodes with the given value
Query	equalTo(double value, String key) Create a query constrained to only return the child node with the given key and value.
Query	equalTo(String value) Create a query constrained to only return child nodes with the given value
Query	equalTo(boolean value, String key) Create a query constrained to only return the child node with the given key and value.
Query	equalTo(boolean value) Create a query constrained to only return child nodes with the given value.
DatabaseReference	getRef()
void	keepSynced(boolean keepSynced) By calling `keepSynced(true)` on a location, the data for that location will automatically be downloaded and kept in sync, even when no listeners are attached for that location.
Query	limitToFirst(int limit) Create a query with limit and anchor it to the start of the window
Query	limitToLast(int limit) Create a query with limit and anchor it to the end of the window
Query	orderByChild(String path) Create a query in which child nodes are ordered by the values of the specified path.
Query	orderByKey() Create a query in which child nodes are ordered by their keys.
Query	orderByPriority() Create a query in which child nodes are ordered by their priorities.
Query	orderByValue() Create a query in which nodes are ordered by their value
void	removeEventListener(ChildEventListener listener) Remove the specified listener from this location.
void	removeEventListener(ValueEventListener listener) Remove the specified listener from this location.
Query	startAt(double value) Create a query constrained to only return child nodes with a value greater than or equal to the given value, using the given orderBy directive or priority as default.
Query	startAt(String value, String key) Create a query constrained to only return child nodes with a value greater than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key greater than or equal to the given key.
Query	startAt(String value) Create a query constrained to only return child nodes with a value greater than or equal to the given value, using the given orderBy directive or priority as default.
Query	startAt(double value, String key) Create a query constrained to only return child nodes with a value greater than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key greater than or equal to the given key.
Query	startAt(boolean value) Create a query constrained to only return child nodes with a value greater than or equal to the given value, using the given orderBy directive or priority as default.
Query	startAt(boolean value, String key) Create a query constrained to only return child nodes with a value greater than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key greater than or equal to the given key.

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 ChildEventListener addChildEventListener (ChildEventListener listener)

Also: Google Play services

Add a listener for child events occurring at this location. When child locations are added, removed, changed, or moved, the listener will be triggered for the appropriate event

Parameters

listener	The listener to be called with changes

Returns

A reference to the listener provided. Save this to remove the listener later.

public void addListenerForSingleValueEvent (ValueEventListener listener)

Also: Google Play services

Add a listener for a single change in the data at this location. This listener will be triggered once with the value of the data at the location.

Parameters

listener	The listener to be called with the data

public ValueEventListener addValueEventListener (ValueEventListener listener)

Also: Google Play services

Add a listener for changes in the data at this location. Each time time the data changes, your listener will be called with an immutable snapshot of the data.

Parameters

listener	The listener to be called with changes

Returns

A reference to the listener provided. Save this to remove the listener later.

public Query endAt (String value, String key)

Also: Google Play services

Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default, and additionally only child nodes with a key key less than or equal to the given key.

Parameters

value	The value to end at, inclusive
key	The key to end at, inclusive

Returns

A Query with the new constraint

public Query endAt (String value)

Also: Google Play services

Create a query constrained to only return child nodes with a value less than or equal to the given value, using the given orderBy directive or priority as default.

Parameters

value	The value to end at, inclusive

Returns

A Query with the new constraint

public Query endAt (double value, String key)

Also: Google Play services

Parameters

value	The value to end at, inclusive
key	The key to end at, inclusive

Returns

A Query with the new constraint