MergeCursor
public
class
MergeCursor
extends AbstractCursor
A convenience class that lets you present an array of Cursors as a single linear Cursor.
The schema of the cursors presented is entirely up to the creator of the MergeCursor, and
may be different if that is desired. Calls to getColumns, getColumnIndex, etc will return the
value for the row that the MergeCursor is currently pointing at.
Summary
Public methods |
void
|
close()
Closes the Cursor, releasing all of its resources and making it completely invalid.
|
void
|
deactivate()
Deactivates the Cursor, making all calls on it fail until requery() is called.
|
byte[]
|
getBlob(int column)
Returns the value of the requested column as a byte array.
|
String[]
|
getColumnNames()
Returns a string array holding the names of all of the columns in the
result set in the order in which they were listed in the result.
|
int
|
getCount()
Returns the numbers of rows in the cursor.
|
double
|
getDouble(int column)
Returns the value of the requested column as a double.
|
float
|
getFloat(int column)
Returns the value of the requested column as a float.
|
int
|
getInt(int column)
Returns the value of the requested column as an int.
|
long
|
getLong(int column)
Returns the value of the requested column as a long.
|
short
|
getShort(int column)
Returns the value of the requested column as a short.
|
String
|
getString(int column)
Returns the value of the requested column as a String.
|
int
|
getType(int column)
Returns data type of the given column's value.
|
boolean
|
isNull(int column)
Returns true if the value in the indicated column is null.
|
boolean
|
onMove(int oldPosition, int newPosition)
This function is called every time the cursor is successfully scrolled
to a new position, giving the subclass a chance to update any state it
may have.
|
void
|
registerContentObserver(ContentObserver observer)
Register an observer that is called when changes happen to the content backing this cursor.
|
void
|
registerDataSetObserver(DataSetObserver observer)
Register an observer that is called when changes happen to the contents
of the this cursors data set, for example, when the data set is changed via
requery() , deactivate() , or close() .
|
boolean
|
requery()
Performs the query that created the cursor again, refreshing its
contents.
|
void
|
unregisterContentObserver(ContentObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver) .
|
void
|
unregisterDataSetObserver(DataSetObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver) .
|
Inherited methods |
From class
android.database.AbstractCursor
void
|
checkPosition()
This function throws CursorIndexOutOfBoundsException if
the cursor position is out of bounds.
|
void
|
close()
Closes the Cursor, releasing all of its resources and making it completely invalid.
|
void
|
copyStringToBuffer(int columnIndex, CharArrayBuffer buffer)
Retrieves the requested column text and stores it in the buffer provided.
|
void
|
deactivate()
Deactivates the Cursor, making all calls on it fail until requery() is called.
|
void
|
fillWindow(int position, CursorWindow window)
Copies cursor data into the window.
|
void
|
finalize()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
|
byte[]
|
getBlob(int column)
Returns the value of the requested column as a byte array.
|
int
|
getColumnCount()
Return total number of columns
|
int
|
getColumnIndex(String columnName)
Returns the zero-based index for the given column name, or -1 if the column doesn't exist.
|
int
|
getColumnIndexOrThrow(String columnName)
Returns the zero-based index for the given column name, or throws
IllegalArgumentException if the column doesn't exist.
|
String
|
getColumnName(int columnIndex)
Returns the column name at the given zero-based column index.
|
abstract
String[]
|
getColumnNames()
Returns a string array holding the names of all of the columns in the
result set in the order in which they were listed in the result.
|
abstract
int
|
getCount()
Returns the numbers of rows in the cursor.
|
abstract
double
|
getDouble(int column)
Returns the value of the requested column as a double.
|
Bundle
|
getExtras()
Returns a bundle of extra values.
|
abstract
float
|
getFloat(int column)
Returns the value of the requested column as a float.
|
abstract
int
|
getInt(int column)
Returns the value of the requested column as an int.
|
abstract
long
|
getLong(int column)
Returns the value of the requested column as a long.
|
Uri
|
getNotificationUri()
Return the URI at which notifications of changes in this Cursor's data
will be delivered, as previously set by setNotificationUri(ContentResolver, Uri) .
|
List<Uri>
|
getNotificationUris()
Return the URIs at which notifications of changes in this Cursor's data
will be delivered, as previously set by setNotificationUris(ContentResolver, List) .
|
final
int
|
getPosition()
Returns the current position of the cursor in the row set.
|
abstract
short
|
getShort(int column)
Returns the value of the requested column as a short.
|
abstract
String
|
getString(int column)
Returns the value of the requested column as a String.
|
int
|
getType(int column)
Returns data type of the given column's value.
|
Object
|
getUpdatedField(int columnIndex)
This method was deprecated
in API level 15.
Always returns null since Cursors do not support updating rows
|
boolean
|
getWantsAllOnMoveCalls()
onMove() will only be called across processes if this method returns true.
|
CursorWindow
|
getWindow()
If the cursor is backed by a CursorWindow , returns a pre-filled
window with the contents of the cursor, otherwise null.
|
final
boolean
|
isAfterLast()
Returns whether the cursor is pointing to the position after the last
row.
|
final
boolean
|
isBeforeFirst()
Returns whether the cursor is pointing to the position before the first
row.
|
boolean
|
isClosed()
return true if the cursor is closed
|
boolean
|
isFieldUpdated(int columnIndex)
This method was deprecated
in API level 15.
Always returns false since Cursors do not support updating rows
|
final
boolean
|
isFirst()
Returns whether the cursor is pointing to the first row.
|
final
boolean
|
isLast()
Returns whether the cursor is pointing to the last row.
|
abstract
boolean
|
isNull(int column)
Returns true if the value in the indicated column is null.
|
final
boolean
|
move(int offset)
Move the cursor by a relative amount, forward or backward, from the
current position.
|
final
boolean
|
moveToFirst()
Move the cursor to the first row.
|
final
boolean
|
moveToLast()
Move the cursor to the last row.
|
final
boolean
|
moveToNext()
Move the cursor to the next row.
|
final
boolean
|
moveToPosition(int position)
Move the cursor to an absolute position.
|
final
boolean
|
moveToPrevious()
Move the cursor to the previous row.
|
void
|
onChange(boolean selfChange)
Subclasses must call this method when they finish committing updates to notify all
observers.
|
boolean
|
onMove(int oldPosition, int newPosition)
This function is called every time the cursor is successfully scrolled
to a new position, giving the subclass a chance to update any state it
may have.
|
void
|
registerContentObserver(ContentObserver observer)
Register an observer that is called when changes happen to the content backing this cursor.
|
void
|
registerDataSetObserver(DataSetObserver observer)
Register an observer that is called when changes happen to the contents
of the this cursors data set, for example, when the data set is changed via
requery() , deactivate() , or close() .
|
boolean
|
requery()
Performs the query that created the cursor again, refreshing its
contents.
|
Bundle
|
respond(Bundle extras)
This is an out-of-band way for the user of a cursor to communicate with the cursor.
|
void
|
setExtras(Bundle extras)
Sets a Bundle that will be returned by getExtras() .
|
void
|
setNotificationUri(ContentResolver cr, Uri notifyUri)
Specifies a content URI to watch for changes.
|
void
|
setNotificationUris(ContentResolver cr, List<Uri> notifyUris)
Similar to setNotificationUri(android.content.ContentResolver, android.net.Uri) , except this version allows
to watch multiple content URIs for changes.
|
void
|
unregisterContentObserver(ContentObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver) .
|
void
|
unregisterDataSetObserver(DataSetObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver) .
|
|
From class
java.lang.Object
Object
|
clone()
Creates and returns a copy of this object.
|
boolean
|
equals(Object obj)
Indicates whether some other object is "equal to" this one.
|
void
|
finalize()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
|
final
Class<?>
|
getClass()
Returns the runtime class of this Object .
|
int
|
hashCode()
Returns a hash code value for the object.
|
final
void
|
notify()
Wakes up a single thread that is waiting on this object's
monitor.
|
final
void
|
notifyAll()
Wakes up all threads that are waiting on this object's monitor.
|
String
|
toString()
Returns a string representation of the object.
|
final
void
|
wait(long timeoutMillis, int nanos)
Causes the current thread to wait until it is awakened, typically
by being notified or interrupted, or until a
certain amount of real time has elapsed.
|
final
void
|
wait(long timeoutMillis)
Causes the current thread to wait until it is awakened, typically
by being notified or interrupted, or until a
certain amount of real time has elapsed.
|
final
void
|
wait()
Causes the current thread to wait until it is awakened, typically
by being notified or interrupted.
|
|
From interface
android.database.CrossProcessCursor
abstract
void
|
fillWindow(int position, CursorWindow window)
Copies cursor data into the window.
|
abstract
CursorWindow
|
getWindow()
Returns a pre-filled window that contains the data within this cursor.
|
abstract
boolean
|
onMove(int oldPosition, int newPosition)
This function is called every time the cursor is successfully scrolled
to a new position, giving the subclass a chance to update any state it
may have.
|
|
From interface
android.database.Cursor
abstract
void
|
close()
Closes the Cursor, releasing all of its resources and making it completely invalid.
|
abstract
void
|
copyStringToBuffer(int columnIndex, CharArrayBuffer buffer)
Retrieves the requested column text and stores it in the buffer provided.
|
abstract
void
|
deactivate()
This method was deprecated
in API level 16.
Since requery() is deprecated, so too is this.
|
abstract
byte[]
|
getBlob(int columnIndex)
Returns the value of the requested column as a byte array.
|
abstract
int
|
getColumnCount()
Return total number of columns
|
abstract
int
|
getColumnIndex(String columnName)
Returns the zero-based index for the given column name, or -1 if the column doesn't exist.
|
abstract
int
|
getColumnIndexOrThrow(String columnName)
Returns the zero-based index for the given column name, or throws
IllegalArgumentException if the column doesn't exist.
|
abstract
String
|
getColumnName(int columnIndex)
Returns the column name at the given zero-based column index.
|
abstract
String[]
|
getColumnNames()
Returns a string array holding the names of all of the columns in the
result set in the order in which they were listed in the result.
|
abstract
int
|
getCount()
Returns the numbers of rows in the cursor.
|
abstract
double
|
getDouble(int columnIndex)
Returns the value of the requested column as a double.
|
abstract
Bundle
|
getExtras()
Returns a bundle of extra values.
|
abstract
float
|
getFloat(int columnIndex)
Returns the value of the requested column as a float.
|
abstract
int
|
getInt(int columnIndex)
Returns the value of the requested column as an int.
|
abstract
long
|
getLong(int columnIndex)
Returns the value of the requested column as a long.
|
abstract
Uri
|
getNotificationUri()
Return the URI at which notifications of changes in this Cursor's data
will be delivered, as previously set by setNotificationUri(ContentResolver, Uri) .
|
default
List<Uri>
|
getNotificationUris()
Return the URIs at which notifications of changes in this Cursor's data
will be delivered, as previously set by setNotificationUris(ContentResolver, List) .
|
abstract
int
|
getPosition()
Returns the current position of the cursor in the row set.
|
abstract
short
|
getShort(int columnIndex)
Returns the value of the requested column as a short.
|
abstract
String
|
getString(int columnIndex)
Returns the value of the requested column as a String.
|
abstract
int
|
getType(int columnIndex)
Returns data type of the given column's value.
|
abstract
boolean
|
getWantsAllOnMoveCalls()
onMove() will only be called across processes if this method returns true.
|
abstract
boolean
|
isAfterLast()
Returns whether the cursor is pointing to the position after the last
row.
|
abstract
boolean
|
isBeforeFirst()
Returns whether the cursor is pointing to the position before the first
row.
|
abstract
boolean
|
isClosed()
return true if the cursor is closed
|
abstract
boolean
|
isFirst()
Returns whether the cursor is pointing to the first row.
|
abstract
boolean
|
isLast()
Returns whether the cursor is pointing to the last row.
|
abstract
boolean
|
isNull(int columnIndex)
Returns true if the value in the indicated column is null.
|
abstract
boolean
|
move(int offset)
Move the cursor by a relative amount, forward or backward, from the
current position.
|
abstract
boolean
|
moveToFirst()
Move the cursor to the first row.
|
abstract
boolean
|
moveToLast()
Move the cursor to the last row.
|
abstract
boolean
|
moveToNext()
Move the cursor to the next row.
|
abstract
boolean
|
moveToPosition(int position)
Move the cursor to an absolute position.
|
abstract
boolean
|
moveToPrevious()
Move the cursor to the previous row.
|
abstract
void
|
registerContentObserver(ContentObserver observer)
Register an observer that is called when changes happen to the content backing this cursor.
|
abstract
void
|
registerDataSetObserver(DataSetObserver observer)
Register an observer that is called when changes happen to the contents
of the this cursors data set, for example, when the data set is changed via
requery() , deactivate() , or close() .
|
abstract
boolean
|
requery()
This method was deprecated
in API level 15.
Don't use this. Just request a new cursor, so you can do this
asynchronously and update your list view once the new cursor comes back.
|
abstract
Bundle
|
respond(Bundle extras)
This is an out-of-band way for the user of a cursor to communicate with the cursor.
|
abstract
void
|
setExtras(Bundle extras)
Sets a Bundle that will be returned by getExtras() .
|
abstract
void
|
setNotificationUri(ContentResolver cr, Uri uri)
Register to watch a content URI for changes.
|
default
void
|
setNotificationUris(ContentResolver cr, List<Uri> uris)
Similar to setNotificationUri(android.content.ContentResolver, android.net.Uri) , except this version allows
to watch multiple content URIs for changes.
|
abstract
void
|
unregisterContentObserver(ContentObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver) .
|
abstract
void
|
unregisterDataSetObserver(DataSetObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver) .
|
|
From interface
java.io.Closeable
abstract
void
|
close()
Closes this stream and releases any system resources associated
with it.
|
|
|
Public constructors
MergeCursor
public MergeCursor (Cursor[] cursors)
Parameters |
cursors |
Cursor |
Public methods
close
public void close ()
Closes the Cursor, releasing all of its resources and making it completely invalid.
Unlike deactivate()
a call to requery()
will not make the Cursor valid
again.
deactivate
public void deactivate ()
Deactivates the Cursor, making all calls on it fail until requery()
is called.
Inactive Cursors use fewer resources than active Cursors.
Calling requery()
will make the cursor active again.
getBlob
public byte[] getBlob (int column)
Returns the value of the requested column as a byte array.
The result and whether this method throws an exception when the
column value is null or the column type is not a blob type is
implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
byte[] |
the value of that column as a byte array. |
getColumnNames
public String[] getColumnNames ()
Returns a string array holding the names of all of the columns in the
result set in the order in which they were listed in the result.
Returns |
String[] |
the names of the columns returned in this query. |
getCount
public int getCount ()
Returns the numbers of rows in the cursor.
Returns |
int |
the number of rows in the cursor.
Value is 0 or greater |
getDouble
public double getDouble (int column)
Returns the value of the requested column as a double.
The result and whether this method throws an exception when the
column value is null, the column type is not a floating-point type, or the
floating-point value is not representable as a double
value is
implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
double |
the value of that column as a double. |
getFloat
public float getFloat (int column)
Returns the value of the requested column as a float.
The result and whether this method throws an exception when the
column value is null, the column type is not a floating-point type, or the
floating-point value is not representable as a float
value is
implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
float |
the value of that column as a float. |
getInt
public int getInt (int column)
Returns the value of the requested column as an int.
The result and whether this method throws an exception when the
column value is null, the column type is not an integral type, or the
integer value is outside the range [Integer.MIN_VALUE
,
Integer.MAX_VALUE
] is implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
int |
the value of that column as an int. |
getLong
public long getLong (int column)
Returns the value of the requested column as a long.
The result and whether this method throws an exception when the
column value is null, the column type is not an integral type, or the
integer value is outside the range [Long.MIN_VALUE
,
Long.MAX_VALUE
] is implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
long |
the value of that column as a long. |
getShort
public short getShort (int column)
Returns the value of the requested column as a short.
The result and whether this method throws an exception when the
column value is null, the column type is not an integral type, or the
integer value is outside the range [Short.MIN_VALUE
,
Short.MAX_VALUE
] is implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
short |
the value of that column as a short. |
getString
public String getString (int column)
Returns the value of the requested column as a String.
The result and whether this method throws an exception when the
column value is null or the column type is not a string type is
implementation-defined.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
String |
the value of that column as a String. |
getType
public int getType (int column)
Returns data type of the given column's value.
The preferred type of the column is returned but the data may be converted to other types
as documented in the get-type methods such as getInt(int)
, getFloat(int)
etc.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
isNull
public boolean isNull (int column)
Returns true
if the value in the indicated column is null.
Parameters |
column |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns |
boolean |
whether the column value is null. |
onMove
public boolean onMove (int oldPosition,
int newPosition)
This function is called every time the cursor is successfully scrolled
to a new position, giving the subclass a chance to update any state it
may have. If it returns false the move function will also do so and the
cursor will scroll to the beforeFirst position.
Parameters |
oldPosition |
int : the position that we're moving from |
newPosition |
int : the position that we're moving to |
Returns |
boolean |
true if the move is successful, false otherwise |
registerContentObserver
public void registerContentObserver (ContentObserver observer)
Register an observer that is called when changes happen to the content backing this cursor.
Typically the data set won't change until requery()
is called.
Parameters |
observer |
ContentObserver : the object that gets notified when the content backing the cursor changes. |
registerDataSetObserver
public void registerDataSetObserver (DataSetObserver observer)
Register an observer that is called when changes happen to the contents
of the this cursors data set, for example, when the data set is changed via
requery()
, deactivate()
, or close()
.
Parameters |
observer |
DataSetObserver : the object that gets notified when the cursors data set changes. |
requery
public boolean requery ()
Performs the query that created the cursor again, refreshing its
contents. This may be done at any time, including after a call to deactivate()
.
Since this method could execute a query on the database and potentially take
a while, it could cause ANR if it is called on Main (UI) thread.
A warning is printed if this method is being executed on Main thread.
Returns |
boolean |
true if the requery succeeded, false if not, in which case the
cursor becomes invalid. |
unregisterContentObserver
public void unregisterContentObserver (ContentObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver)
.
Parameters |
observer |
ContentObserver : the object to unregister. |
unregisterDataSetObserver
public void unregisterDataSetObserver (DataSetObserver observer)
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver)
.
Parameters |
observer |
DataSetObserver : the object to unregister. |