CursorWrapper
public
class
CursorWrapper
extends Object
implements
Cursor
java.lang.Object | |
↳ | android.database.CursorWrapper |
Wrapper class for Cursor that delegates all calls to the actual cursor object. The primary use for this class is to extend a cursor while overriding only a subset of its methods.
Summary
Inherited constants |
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Public constructors | |
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CursorWrapper(Cursor cursor)
Creates a cursor wrapper. |
Public methods | |
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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 |
byte[]
|
getBlob(int columnIndex)
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
|
String
|
getColumnName(int columnIndex)
Returns the column name at the given zero-based column index. |
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 columnIndex)
Returns the value of the requested column as a double. |
Bundle
|
getExtras()
Returns a bundle of extra values. |
float
|
getFloat(int columnIndex)
Returns the value of the requested column as a float. |
int
|
getInt(int columnIndex)
Returns the value of the requested column as an int. |
long
|
getLong(int columnIndex)
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 |
List<Uri>
|
getNotificationUris()
Return the URIs at which notifications of changes in this Cursor's data
will be delivered, as previously set by |
int
|
getPosition()
Returns the current position of the cursor in the row set. |
short
|
getShort(int columnIndex)
Returns the value of the requested column as a short. |
String
|
getString(int columnIndex)
Returns the value of the requested column as a String. |
int
|
getType(int columnIndex)
Returns data type of the given column's value. |
boolean
|
getWantsAllOnMoveCalls()
onMove() will only be called across processes if this method returns true. |
Cursor
|
getWrappedCursor()
Gets the underlying cursor that is wrapped by this instance. |
boolean
|
isAfterLast()
Returns whether the cursor is pointing to the position after the last row. |
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
|
isFirst()
Returns whether the cursor is pointing to the first row. |
boolean
|
isLast()
Returns whether the cursor is pointing to the last row. |
boolean
|
isNull(int columnIndex)
Returns |
boolean
|
move(int offset)
Move the cursor by a relative amount, forward or backward, from the current position. |
boolean
|
moveToFirst()
Move the cursor to the first row. |
boolean
|
moveToLast()
Move the cursor to the last row. |
boolean
|
moveToNext()
Move the cursor to the next row. |
boolean
|
moveToPosition(int position)
Move the cursor to an absolute position. |
boolean
|
moveToPrevious()
Move the cursor to the previous row. |
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
|
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 |
void
|
setNotificationUri(ContentResolver cr, Uri uri)
Register to watch a content URI for changes. |
void
|
setNotificationUris(ContentResolver cr, List<Uri> uris)
Similar to |
void
|
unregisterContentObserver(ContentObserver observer)
Unregister an observer that has previously been registered with this
cursor via |
void
|
unregisterDataSetObserver(DataSetObserver observer)
Unregister an observer that has previously been registered with this
cursor via |
Inherited methods | |
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Public constructors
CursorWrapper
public CursorWrapper (Cursor cursor)
Creates a cursor wrapper.
Parameters | |
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cursor |
Cursor : The underlying cursor to wrap. |
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.
copyStringToBuffer
public void copyStringToBuffer (int columnIndex, CharArrayBuffer buffer)
Retrieves the requested column text and stores it in the buffer provided. If the buffer size is not sufficient, a new char buffer will be allocated and assigned to CharArrayBuffer.data
Parameters | |
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columnIndex |
int : the zero-based index of the target column.
if the target column is null, return buffer
Value is 0 or greater |
buffer |
CharArrayBuffer : the buffer to copy the text into. |
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 columnIndex)
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 | |
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columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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byte[] |
the value of that column as a byte array. |
getColumnCount
public int getColumnCount ()
Return total number of columns
Returns | |
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int |
number of columns Value is 0 or greater |
getColumnIndex
public int getColumnIndex (String columnName)
Returns the zero-based index for the given column name, or -1 if the column doesn't exist.
If you expect the column to exist use getColumnIndexOrThrow(java.lang.String)
instead, which
will make the error more clear.
Parameters | |
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columnName |
String : the name of the target column. |
Returns | |
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int |
the zero-based column index for the given column name, or -1 if the column name does not exist. Value is -1 or greater |
getColumnIndexOrThrow
public int getColumnIndexOrThrow (String columnName)
Returns the zero-based index for the given column name, or throws
IllegalArgumentException
if the column doesn't exist. If you're not sure if
a column will exist or not use getColumnIndex(java.lang.String)
and check for -1, which
is more efficient than catching the exceptions.
Parameters | |
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columnName |
String : the name of the target column. |
Returns | |
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int |
the zero-based column index for the given column name Value is 0 or greater |
Throws | |
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IllegalArgumentException |
getColumnName
public String getColumnName (int columnIndex)
Returns the column name at the given zero-based column index.
Parameters | |
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columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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String |
the column name for the given column index. |
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 | |
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String[] |
the names of the columns returned in this query. |
getCount
public int getCount ()
Returns the numbers of rows in the cursor.
Returns | |
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int |
the number of rows in the cursor. Value is 0 or greater |
getDouble
public double getDouble (int columnIndex)
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 | |
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columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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double |
the value of that column as a double. |
getExtras
public Bundle getExtras ()
Returns a bundle of extra values. This is an optional way for cursors to provide out-of-band metadata to their users. One use of this is for reporting on the progress of network requests that are required to fetch data for the cursor.
These values may only change when requery is called.
Returns | |
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Bundle |
cursor-defined values, or Bundle.EMPTY if there
are no values. Never null . |
getFloat
public float getFloat (int columnIndex)
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 | |
---|---|
columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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float |
the value of that column as a float. |
getInt
public int getInt (int columnIndex)
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 | |
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columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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int |
the value of that column as an int. |
getLong
public long getLong (int columnIndex)
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 | |
---|---|
columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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long |
the value of that column as a long. |
getNotificationUri
public 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)
.
Returns | |
---|---|
Uri |
Returns a URI that can be used with
ContentResolver.registerContentObserver to find out about changes to this Cursor's
data. May be null if no notification URI has been set. |
getNotificationUris
public 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)
.
If this is not implemented, this is equivalent to calling getNotificationUri()
.
Returns | |
---|---|
List<Uri> |
Returns URIs that can be used with
ContentResolver.registerContentObserver to find out about changes to this Cursor's
data. May be null if no notification URI has been set. |
getPosition
public int getPosition ()
Returns the current position of the cursor in the row set. The value is zero-based. When the row set is first returned the cursor will be at positon -1, which is before the first row. After the last row is returned another call to next() will leave the cursor past the last entry, at a position of count().
Returns | |
---|---|
int |
the current cursor position. Value is -1 or greater |
getShort
public short getShort (int columnIndex)
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 | |
---|---|
columnIndex |
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 columnIndex)
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 | |
---|---|
columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
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String |
the value of that column as a String. |
getType
public int getType (int columnIndex)
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 | |
---|---|
columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
---|---|
int |
column value type
Value is FIELD_TYPE_NULL , FIELD_TYPE_INTEGER , FIELD_TYPE_FLOAT , FIELD_TYPE_STRING , or FIELD_TYPE_BLOB |
getWantsAllOnMoveCalls
public boolean getWantsAllOnMoveCalls ()
onMove() will only be called across processes if this method returns true.
Returns | |
---|---|
boolean |
whether all cursor movement should result in a call to onMove(). |
getWrappedCursor
public Cursor getWrappedCursor ()
Gets the underlying cursor that is wrapped by this instance.
Returns | |
---|---|
Cursor |
The wrapped cursor. |
isAfterLast
public boolean isAfterLast ()
Returns whether the cursor is pointing to the position after the last row.
Returns | |
---|---|
boolean |
whether the cursor is after the last result. |
isBeforeFirst
public boolean isBeforeFirst ()
Returns whether the cursor is pointing to the position before the first row.
Returns | |
---|---|
boolean |
whether the cursor is before the first result. |
isClosed
public boolean isClosed ()
return true if the cursor is closed
Returns | |
---|---|
boolean |
true if the cursor is closed. |
isFirst
public boolean isFirst ()
Returns whether the cursor is pointing to the first row.
Returns | |
---|---|
boolean |
whether the cursor is pointing at the first entry. |
isLast
public boolean isLast ()
Returns whether the cursor is pointing to the last row.
Returns | |
---|---|
boolean |
whether the cursor is pointing at the last entry. |
isNull
public boolean isNull (int columnIndex)
Returns true
if the value in the indicated column is null.
Parameters | |
---|---|
columnIndex |
int : the zero-based index of the target column.
Value is 0 or greater |
Returns | |
---|---|
boolean |
whether the column value is null. |
move
public boolean move (int offset)
Move the cursor by a relative amount, forward or backward, from the current position. Positive offsets move forwards, negative offsets move backwards. If the final position is outside of the bounds of the result set then the resultant position will be pinned to -1 or count() depending on whether the value is off the front or end of the set, respectively.
This method will return true if the requested destination was reachable, otherwise, it returns false. For example, if the cursor is at currently on the second entry in the result set and move(-5) is called, the position will be pinned at -1, and false will be returned.
Parameters | |
---|---|
offset |
int : the offset to be applied from the current position. |
Returns | |
---|---|
boolean |
whether the requested move fully succeeded. |
moveToFirst
public boolean moveToFirst ()
Move the cursor to the first row.
This method will return false if the cursor is empty.
Returns | |
---|---|
boolean |
whether the move succeeded. |
moveToLast
public boolean moveToLast ()
Move the cursor to the last row.
This method will return false if the cursor is empty.
Returns | |
---|---|
boolean |
whether the move succeeded. |
moveToNext
public boolean moveToNext ()
Move the cursor to the next row.
This method will return false if the cursor is already past the last entry in the result set.
Returns | |
---|---|
boolean |
whether the move succeeded. |
moveToPosition
public boolean moveToPosition (int position)
Move the cursor to an absolute position. The valid range of values is -1 <= position <= count.
This method will return true if the request destination was reachable, otherwise, it returns false.
Parameters | |
---|---|
position |
int : the zero-based position to move to.
Value is -1 or greater |
Returns | |
---|---|
boolean |
whether the requested move fully succeeded. |
moveToPrevious
public boolean moveToPrevious ()
Move the cursor to the previous row.
This method will return false if the cursor is already before the first entry in the result set.
Returns | |
---|---|
boolean |
whether the move succeeded. |
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. |
respond
public Bundle respond (Bundle extras)
This is an out-of-band way for the user of a cursor to communicate with the cursor. The structure of each bundle is entirely defined by the cursor.
One use of this is to tell a cursor that it should retry its network request after it reported an error.
Parameters | |
---|---|
extras |
Bundle : extra values, or Bundle.EMPTY .
Never null . |
Returns | |
---|---|
Bundle |
extra values, or Bundle.EMPTY .
Never null . |
setExtras
public void setExtras (Bundle extras)
Sets a Bundle
that will be returned by getExtras()
.
Parameters | |
---|---|
extras |
Bundle : Bundle to set, or null to set an empty bundle. |
setNotificationUri
public void setNotificationUri (ContentResolver cr, Uri uri)
Register to watch a content URI for changes. This can be the URI of a specific data row (for example, "content://my_provider_type/23"), or a a generic URI for a content type.
Calling this overrides any previous call to
setNotificationUris(android.content.ContentResolver, java.util.List)
.
Parameters | |
---|---|
cr |
ContentResolver : The content resolver from the caller's context. The listener attached to
this resolver will be notified. |
uri |
Uri : The content URI to watch. |
setNotificationUris
public 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.
If this is not implemented, this is equivalent to calling
setNotificationUri(android.content.ContentResolver, android.net.Uri)
with the first URI in uris
.
Calling this overrides any previous call to
setNotificationUri(android.content.ContentResolver, android.net.Uri)
.
Parameters | |
---|---|
cr |
ContentResolver : The content resolver from the caller's context. The listener attached to
this resolver will be notified.
This value cannot be null . |
uris |
List : The content URIs to watch.
This value cannot be null . |
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. |