Cursor
interface Cursor : Closeable
android.database.Cursor |
This interface provides random read-write access to the result set returned by a database query.
Cursor implementations are not required to be synchronized so code using a Cursor from multiple threads should perform its own synchronization when using the Cursor.
Implementations should subclass AbstractCursor
.
Summary
Constants | |
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static Int |
Value returned by |
static Int |
Value returned by |
static Int |
Value returned by |
static Int |
Value returned by |
static Int |
Value returned by |
Public methods | |
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abstract Unit |
close() Closes the Cursor, releasing all of its resources and making it completely invalid. |
abstract Unit |
copyStringToBuffer(columnIndex: Int, buffer: CharArrayBuffer!) Retrieves the requested column text and stores it in the buffer provided. |
abstract Unit |
Deactivates the Cursor, making all calls on it fail until |
abstract ByteArray! |
Returns the value of the requested column as a byte array. |
abstract Int |
Return total number of columns |
abstract Int |
getColumnIndex(columnName: String!) Returns the zero-based index for the given column name, or -1 if the column doesn't exist. |
abstract Int |
getColumnIndexOrThrow(columnName: String!) Returns the zero-based index for the given column name, or throws |
abstract String! |
getColumnName(columnIndex: Int) Returns the column name at the given zero-based column index. |
abstract Array<String!>! |
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 |
Returns the value of the requested column as a double. |
abstract Bundle! |
Returns a bundle of extra values. |
abstract Float |
Returns the value of the requested column as a float. |
abstract Int |
Returns the value of the requested column as an int. |
abstract Long |
Returns the value of the requested column as a long. |
abstract Uri! |
Return the URI at which notifications of changes in this Cursor's data will be delivered, as previously set by |
open MutableList<Uri!>? |
Return the URIs at which notifications of changes in this Cursor's data will be delivered, as previously set by |
abstract Int |
Returns the current position of the cursor in the row set. |
abstract Short |
Returns the value of the requested column as a short. |
abstract String! |
Returns the value of the requested column as a String. |
abstract Int |
Returns data type of the given column's value. |
abstract Boolean |
onMove() will only be called across processes if this method returns true. |
abstract Boolean |
Returns whether the cursor is pointing to the position after the last row. |
abstract Boolean |
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 |
Returns |
abstract Boolean |
Move the cursor by a relative amount, forward or backward, from the current position. |
abstract Boolean |
Move the cursor to the first row. |
abstract Boolean |
Move the cursor to the last row. |
abstract Boolean |
Move the cursor to the next row. |
abstract Boolean |
moveToPosition(position: Int) Move the cursor to an absolute position. |
abstract Boolean |
Move the cursor to the previous row. |
abstract Unit |
registerContentObserver(observer: ContentObserver!) Register an observer that is called when changes happen to the content backing this cursor. |
abstract Unit |
registerDataSetObserver(observer: DataSetObserver!) 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 |
abstract Boolean |
requery() Performs the query that created the cursor again, refreshing its contents. |
abstract Bundle! |
This is an out-of-band way for the user of a cursor to communicate with the cursor. |
abstract Unit |
Sets a |
abstract Unit |
setNotificationUri(cr: ContentResolver!, uri: Uri!) Register to watch a content URI for changes. |
open Unit |
setNotificationUris(cr: ContentResolver, uris: MutableList<Uri!>) Similar to |
abstract Unit |
unregisterContentObserver(observer: ContentObserver!) Unregister an observer that has previously been registered with this cursor via |
abstract Unit |
unregisterDataSetObserver(observer: DataSetObserver!) Unregister an observer that has previously been registered with this cursor via |
Constants
FIELD_TYPE_BLOB
static val FIELD_TYPE_BLOB: Int
Value returned by getType(int)
if the specified column type is blob
Value: 4
FIELD_TYPE_FLOAT
static val FIELD_TYPE_FLOAT: Int
Value returned by getType(int)
if the specified column type is float
Value: 2
FIELD_TYPE_INTEGER
static val FIELD_TYPE_INTEGER: Int
Value returned by getType(int)
if the specified column type is integer
Value: 1
FIELD_TYPE_NULL
static val FIELD_TYPE_NULL: Int
Value returned by getType(int)
if the specified column is null
Value: 0
FIELD_TYPE_STRING
static val FIELD_TYPE_STRING: Int
Value returned by getType(int)
if the specified column type is string
Value: 3
Public methods
close
abstract fun close(): Unit
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.
Exceptions | |
---|---|
java.lang.Exception |
if this resource cannot be closed |
java.io.IOException |
if an I/O error occurs |
copyStringToBuffer
abstract fun copyStringToBuffer(
columnIndex: Int,
buffer: CharArrayBuffer!
): Unit
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 | |
---|---|
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
abstract fundeactivate(): Unit
Deprecated: Since requery()
is deprecated, so too is this.
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
abstract fun getBlob(columnIndex: Int): ByteArray!
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 | |
---|---|
columnIndex |
Int: the zero-based index of the target column. Value is 0 or greater |
Return | |
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ByteArray! |
the value of that column as a byte array. |
getColumnCount
abstract fun getColumnCount(): Int
Return total number of columns
Return | |
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Int |
number of columns Value is 0 or greater |
getColumnIndex
abstract fun getColumnIndex(columnName: String!): Int
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. |
Return | |
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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 |
See Also
getColumnIndexOrThrow
abstract fun getColumnIndexOrThrow(columnName: String!): Int
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. |
Return | |
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Int |
the zero-based column index for the given column name Value is 0 or greater |
Exceptions | |
---|---|
java.lang.IllegalArgumentException |
if the column does not exist |
See Also
getColumnName
abstract fun getColumnName(columnIndex: Int): String!
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 |
Return | |
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String! |
the column name for the given column index. |
getColumnNames
abstract fun getColumnNames(): Array<String!>!
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.
Return | |
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Array<String!>! |
the names of the columns returned in this query. |
getCount
abstract fun getCount(): Int
Returns the numbers of rows in the cursor.
Return | |
---|---|
Int |
the number of rows in the cursor. Value is 0 or greater |
getDouble
abstract fun getDouble(columnIndex: Int): Double
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 |
Return | |
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Double |
the value of that column as a double. |
getExtras
abstract fun getExtras(): Bundle!
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.
Return | |
---|---|
Bundle! |
cursor-defined values, or Bundle.EMPTY if there are no values. Never null . |
getFloat
abstract fun getFloat(columnIndex: Int): Float
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 |
Return | |
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Float |
the value of that column as a float. |
getInt
abstract fun getInt(columnIndex: Int): Int
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 |
Return | |
---|---|
Int |
the value of that column as an int. |
getLong
abstract fun getLong(columnIndex: Int): Long
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 |
Return | |
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Long |
the value of that column as a long. |
getNotificationUri
abstract fun getNotificationUri(): Uri!
Return the URI at which notifications of changes in this Cursor's data will be delivered, as previously set by setNotificationUri
.
Return | |
---|---|
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
open fun getNotificationUris(): MutableList<Uri!>?
Return the URIs at which notifications of changes in this Cursor's data will be delivered, as previously set by setNotificationUris
.
If this is not implemented, this is equivalent to calling getNotificationUri()
.
Return | |
---|---|
MutableList<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
abstract fun getPosition(): Int
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().
Return | |
---|---|
Int |
the current cursor position. Value is -1 or greater |
getShort
abstract fun getShort(columnIndex: Int): Short
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 |
Return | |
---|---|
Short |
the value of that column as a short. |
getString
abstract fun getString(columnIndex: Int): String!
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 |
Return | |
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String! |
the value of that column as a String. |
getType
abstract fun getType(columnIndex: Int): Int
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 |
getWantsAllOnMoveCalls
abstract fun getWantsAllOnMoveCalls(): Boolean
onMove() will only be called across processes if this method returns true.
Return | |
---|---|
Boolean |
whether all cursor movement should result in a call to onMove(). |
isAfterLast
abstract fun isAfterLast(): Boolean
Returns whether the cursor is pointing to the position after the last row.
Return | |
---|---|
Boolean |
whether the cursor is after the last result. |
isBeforeFirst
abstract fun isBeforeFirst(): Boolean
Returns whether the cursor is pointing to the position before the first row.
Return | |
---|---|
Boolean |
whether the cursor is before the first result. |
isClosed
abstract fun isClosed(): Boolean
return true if the cursor is closed
Return | |
---|---|
Boolean |
true if the cursor is closed. |
isFirst
abstract fun isFirst(): Boolean
Returns whether the cursor is pointing to the first row.
Return | |
---|---|
Boolean |
whether the cursor is pointing at the first entry. |
isLast
abstract fun isLast(): Boolean
Returns whether the cursor is pointing to the last row.
Return | |
---|---|
Boolean |
whether the cursor is pointing at the last entry. |
isNull
abstract fun isNull(columnIndex: Int): Boolean
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 |
Return | |
---|---|
Boolean |
whether the column value is null. |
move
abstract fun move(offset: Int): Boolean
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 | |
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offset |
Int: the offset to be applied from the current position. |
Return | |
---|---|
Boolean |
whether the requested move fully succeeded. |
moveToFirst
abstract fun moveToFirst(): Boolean
Move the cursor to the first row.
This method will return false if the cursor is empty.
Return | |
---|---|
Boolean |
whether the move succeeded. |
moveToLast
abstract fun moveToLast(): Boolean
Move the cursor to the last row.
This method will return false if the cursor is empty.
Return | |
---|---|
Boolean |
whether the move succeeded. |
moveToNext
abstract fun moveToNext(): Boolean
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.
Return | |
---|---|
Boolean |
whether the move succeeded. |
moveToPosition
abstract fun moveToPosition(position: Int): Boolean
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 |
Return | |
---|---|
Boolean |
whether the requested move fully succeeded. |
moveToPrevious
abstract fun moveToPrevious(): Boolean
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.
Return | |
---|---|
Boolean |
whether the move succeeded. |
registerContentObserver
abstract fun registerContentObserver(observer: ContentObserver!): Unit
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
abstract fun registerDataSetObserver(observer: DataSetObserver!): Unit
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
abstract funrequery(): Boolean
Deprecated: 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.
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.
Return | |
---|---|
Boolean |
true if the requery succeeded, false if not, in which case the cursor becomes invalid. |
respond
abstract fun respond(extras: Bundle!): Bundle!
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 . |
Return | |
---|---|
Bundle! |
extra values, or Bundle.EMPTY . Never null . |
setExtras
abstract fun setExtras(extras: Bundle!): Unit
Sets a Bundle
that will be returned by getExtras()
.
Parameters | |
---|---|
extras |
Bundle!: Bundle to set, or null to set an empty bundle. |
setNotificationUri
abstract fun setNotificationUri(
cr: ContentResolver!,
uri: Uri!
): Unit
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
open fun setNotificationUris(
cr: ContentResolver,
uris: MutableList<Uri!>
): Unit
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 |
MutableList<Uri!>: The content URIs to watch. This value cannot be null . |
unregisterContentObserver
abstract fun unregisterContentObserver(observer: ContentObserver!): Unit
Unregister an observer that has previously been registered with this cursor via registerContentObserver
.
Parameters | |
---|---|
observer |
ContentObserver!: the object to unregister. |
unregisterDataSetObserver
abstract fun unregisterDataSetObserver(observer: DataSetObserver!): Unit
Unregister an observer that has previously been registered with this cursor via registerContentObserver
.
Parameters | |
---|---|
observer |
DataSetObserver!: the object to unregister. |