Query
Known Direct Subclasses
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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 | |
| 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 | 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
| 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
publicChildEventListeneraddChildEventListener(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 |
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Returns
- A reference to the listener provided. Save this to remove the listener later.
public voidaddListenerForSingleValueEvent(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 |
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publicValueEventListeneraddValueEventListener(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 |
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Returns
- A reference to the listener provided. Save this to remove the listener later.
publicQueryendAt(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
publicQueryendAt(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 |
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Returns
- A Query with the new constraint
publicQueryendAt(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
publicQueryendAt(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 |
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Returns
- A Query with the new constraint
publicQueryendAt(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
publicQueryendAt(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
publicQueryequalTo(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
publicQueryequalTo(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
publicQueryequalTo(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
publicQueryequalTo(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
publicQueryequalTo(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
publicQueryequalTo(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 voidkeepSynced(boolean keepSynced)
By callingkeepSynced(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 | Passtrue to keep this location synchronized, passfalse to stop synchronization. |
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publicQuerylimitToFirst(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 |
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Returns
- A Query with the new constraint
publicQuerylimitToLast(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 |
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Returns
- A Query with the new constraint
publicQueryorderByChild(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 |
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Returns
- A Query with the new constraint
publicQueryorderByKey()
Create a query in which child nodes are ordered by their keys.
Returns
- A Query with the new constraint
publicQueryorderByPriority()
Create a query in which child nodes are ordered by their priorities.
Returns
- A Query with the new constraint
publicQueryorderByValue()
Create a query in which nodes are ordered by their value
Returns
- A Query with the new constraint
public voidremoveEventListener(ChildEventListener listener)
Remove the specified listener from this location.
Parameters
| listener | The listener to remove |
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public voidremoveEventListener(ValueEventListener listener)
Remove the specified listener from this location.
Parameters
| listener | The listener to remove |
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publicQuerystartAt(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
publicQuerystartAt(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
publicQuerystartAt(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
publicQuerystartAt(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
publicQuerystartAt(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
publicQuerystartAt(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
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Last updated 2021-04-28 UTC.