public class

Query

extends Object
java.lang.Object
   ↳ com.google.firebase.database.Query
Known Direct Subclasses

Class Overview

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.

Summary

Public Methods
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.
[Expand]
Inherited Methods
From class java.lang.Object

Public Methods

public ChildEventListener addChildEventListener (ChildEventListener listener)

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 ChildEventListener: The listener to be called with changes
Returns
ChildEventListener A reference to the listener provided. Save this to remove the listener later.

public void addListenerForSingleValueEvent (ValueEventListener listener)

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 ValueEventListener: The listener to be called with the data

public ValueEventListener addValueEventListener (ValueEventListener listener)

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 ValueEventListener: The listener to be called with changes
Returns
ValueEventListener A reference to the listener provided. Save this to remove the listener later.

public 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.

Parameters
value String: The value to end at, inclusive
key String: The key to end at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value String: The value to end at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value double: The value to end at, inclusive
key String: The key to end at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value double: The value to end at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value boolean: The value to end at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value boolean: The value to end at, inclusive
key String: The key to end at, inclusive
Returns
Query A Query with the new constraint

public Query equalTo (String value, String key)

Create a query constrained to only return the child node with the given key and value. Note that there is at most one such child as names are unique.

Parameters
value String: The value to query for
key String: The key of the child
Returns
Query A query with the new constraint

public Query equalTo (double value)

Create a query constrained to only return child nodes with the given value

Parameters
value double: The value to query for
Returns
Query A query with the new constraint

public Query equalTo (double value, String key)

Create a query constrained to only return the child node with the given key and value. Note that there is at most one such child as keys are unique.

Parameters
value double: The value to query for
key String: The key of the child
Returns
Query A query with the new constraint

public Query equalTo (String value)

Create a query constrained to only return child nodes with the given value

Parameters
value String: The value to query for
Returns
Query A query with the new constraint

public Query equalTo (boolean value, String key)

Create a query constrained to only return the child node with the given key and value. Note that there is at most one such child as keys are unique.

Parameters
value boolean: The value to query for
key String: The name of the child
Returns
Query A query with the new constraint

public Query equalTo (boolean value)

Create a query constrained to only return child nodes with the given value.

Parameters
value boolean: The value to query for
Returns
Query A query with the new constraint

public DatabaseReference getRef ()

Returns
DatabaseReference A DatabaseReference to this location

public 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. Additionally, while a location is kept synced, it will not be evicted from the persistent disk cache.

Parameters
keepSynced boolean: Pass `true` to keep this location synchronized, pass `false` to stop synchronization.

public Query limitToFirst (int limit)

Create a query with limit and anchor it to the start of the window

Parameters
limit int: The maximum number of child nodes to return
Returns
Query A Query with the new constraint

public Query limitToLast (int limit)

Create a query with limit and anchor it to the end of the window

Parameters
limit int: The maximum number of child nodes to return
Returns
Query A Query with the new constraint

public Query orderByChild (String path)

Create a query in which child nodes are ordered by the values of the specified path.

Parameters
path String: The path to the child node to use for sorting
Returns
Query A Query with the new constraint

public Query orderByKey ()

Create a query in which child nodes are ordered by their keys.

Returns
Query A Query with the new constraint

public Query orderByPriority ()

Create a query in which child nodes are ordered by their priorities.

Returns
Query A Query with the new constraint

public Query orderByValue ()

Create a query in which nodes are ordered by their value

Returns
Query A Query with the new constraint

public void removeEventListener (ChildEventListener listener)

Remove the specified listener from this location.

Parameters
listener ChildEventListener: The listener to remove

public void removeEventListener (ValueEventListener listener)

Remove the specified listener from this location.

Parameters
listener ValueEventListener: The listener to remove

public 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.

Parameters
value double: The value to start at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value String: The priority to start at, inclusive
key String: The key to start at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value String: The value to start at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value double: The priority to start at, inclusive
key String: The key name to start at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value boolean: The value to start at, inclusive
Returns
Query A Query with the new constraint

public 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.

Parameters
value boolean: The priority to start at, inclusive
key String: The key to start at, inclusive
Returns
Query A Query with the new constraint