| Known Direct Subclasses |
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 | |
| Query | |
| Query | |
| 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 | |
| Query | |
| Query |
equalTo(double value)
Create a query constrained to only return child nodes with the given value
|
| Query | |
| Query | |
| Query | |
| 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 | |
| void | |
| 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 | |
| Query | |
| Query | |
| 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 |
Inherited Method Summary
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 | 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)
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)
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)
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)
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)
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 | The value to end at, inclusive |
|---|---|
| key | The key to end at, inclusive |
Returns
- 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 | The value to end at, inclusive |
|---|
Returns
- 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 | The value to end at, inclusive |
|---|
Returns
- 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 | The value to end at, inclusive |
|---|---|
| key | The key to end at, inclusive |
Returns
- 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 | The value to query for |
|---|---|
| key | The key of the child |
Returns
- 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 | The value to query for |
|---|
Returns
- 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 | The value to query for |
|---|---|
| key | The key of the child |
Returns
- 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 | The value to query for |
|---|
Returns
- 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 | The value to query for |
|---|---|
| key | The name of the child |
Returns
- 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 | The value to query for |
|---|
Returns
- A query with the new constraint
public DatabaseReference getRef ()
Returns
- 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 | 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 | The maximum number of child nodes to return |
|---|
Returns
- 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 | The maximum number of child nodes to return |
|---|
Returns
- 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 | The path to the child node to use for sorting |
|---|
Returns
- A Query with the new constraint
public Query orderByKey ()
Create a query in which child nodes are ordered by their keys.
Returns
- A Query with the new constraint
public Query orderByPriority ()
Create a query in which child nodes are ordered by their priorities.
Returns
- A Query with the new constraint
public Query orderByValue ()
Create a query in which nodes are ordered by their value
Returns
- A Query with the new constraint
public void removeEventListener (ChildEventListener listener)
Remove the specified listener from this location.
Parameters
| listener | The listener to remove |
|---|
public void removeEventListener (ValueEventListener listener)
Remove the specified listener from this location.
Parameters
| listener | 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 | The value to start at, inclusive |
|---|
Returns
- 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 | The priority to start at, inclusive |
|---|---|
| key | The key to start at, inclusive |
Returns
- 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 | The value to start at, inclusive |
|---|
Returns
- 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 | The priority to start at, inclusive |
|---|---|
| key | The key name to start at, inclusive |
Returns
- 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 | The value to start at, inclusive |
|---|
Returns
- 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 | The priority to start at, inclusive |
|---|---|
| key | The key to start at, inclusive |
Returns
- A Query with the new constraint