/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.database;
import android.content.ContentResolver;
import android.net.Uri;
import android.os.Bundle;
import java.util.Map;
/**
* This interface provides random read-write access to the result set returned
* by a database query.
*/
public interface Cursor {
/**
* Returns the numbers of rows in the cursor.
*
* @return the number of rows in the cursor.
*/
int getCount();
/**
* 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 the current cursor position.
*/
int getPosition();
/**
* 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.
*
* <p>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.
*
* @param offset the offset to be applied from the current position.
* @return whether the requested move fully succeeded.
*/
boolean move(int offset);
/**
* Move the cursor to an absolute position. The valid
* range of values is -1 <= position <= count.
*
* <p>This method will return true if the request destination was reachable,
* otherwise, it returns false.
*
* @param position the zero-based position to move to.
* @return whether the requested move fully succeeded.
*/
boolean moveToPosition(int position);
/**
* Move the cursor to the first row.
*
* <p>This method will return false if the cursor is empty.
*
* @return whether the move succeeded.
*/
boolean moveToFirst();
/**
* Move the cursor to the last row.
*
* <p>This method will return false if the cursor is empty.
*
* @return whether the move succeeded.
*/
boolean moveToLast();
/**
* Move the cursor to the next row.
*
* <p>This method will return false if the cursor is already past the
* last entry in the result set.
*
* @return whether the move succeeded.
*/
boolean moveToNext();
/**
* Move the cursor to the previous row.
*
* <p>This method will return false if the cursor is already before the
* first entry in the result set.
*
* @return whether the move succeeded.
*/
boolean moveToPrevious();
/**
* Returns whether the cursor is pointing to the first row.
*
* @return whether the cursor is pointing at the first entry.
*/
boolean isFirst();
/**
* Returns whether the cursor is pointing to the last row.
*
* @return whether the cursor is pointing at the last entry.
*/
boolean isLast();
/**
* Returns whether the cursor is pointing to the position before the first
* row.
*
* @return whether the cursor is before the first result.
*/
boolean isBeforeFirst();
/**
* Returns whether the cursor is pointing to the position after the last
* row.
*
* @return whether the cursor is after the last result.
*/
boolean isAfterLast();
/**
* Removes the row at the current cursor position from the underlying data
* store. After this method returns the cursor will be pointing to the row
* after the row that is deleted. This has the side effect of decrementing
* the result of count() by one.
* <p>
* The query must have the row ID column in its selection, otherwise this
* call will fail.
*
* @hide
* @return whether the record was successfully deleted.
* @deprecated use {@link ContentResolver#delete(Uri, String, String[])}
*/
@Deprecated
boolean deleteRow();
/**
* 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 {@link #getColumnIndexOrThrow(String)} instead, which
* will make the error more clear.
*
* @param columnName the name of the target column.
* @return the zero-based column index for the given column name, or -1 if
* the column name does not exist.
* @see #getColumnIndexOrThrow(String)
*/
int getColumnIndex(String columnName);
/**
* Returns the zero-based index for the given column name, or throws
* {@link IllegalArgumentException} if the column doesn't exist. If you're not sure if
* a column will exist or not use {@link #getColumnIndex(String)} and check for -1, which
* is more efficient than catching the exceptions.
*
* @param columnName the name of the target column.
* @return the zero-based column index for the given column name
* @see #getColumnIndex(String)
* @throws IllegalArgumentException if the column does not exist
*/
int getColumnIndexOrThrow(String columnName) throws IllegalArgumentException;
/**
* Returns the column name at the given zero-based column index.
*
* @param columnIndex the zero-based index of the target column.
* @return the column name for the given column index.
*/
String getColumnName(int columnIndex);
/**
* 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 the names of the columns returned in this query.
*/
String[] getColumnNames();
/**
* Return total number of columns
* @return number of columns
*/
int getColumnCount();
/**
* Returns the value of the requested column as a byte array.
*
* <p>If the native content of that column is not blob exception may throw
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as a byte array.
*/
byte[] getBlob(int columnIndex);
/**
* Returns the value of the requested column as a String.
*
* <p>If the native content of that column is not text the result will be
* the result of passing the column value to String.valueOf(x).
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as a String.
*/
String getString(int columnIndex);
/**
* 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
* @param columnIndex the zero-based index of the target column.
* if the target column is null, return buffer
* @param buffer the buffer to copy the text into.
*/
void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer);
/**
* Returns the value of the requested column as a short.
*
* <p>If the native content of that column is not numeric the result will be
* the result of passing the column value to Short.valueOf(x).
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as a short.
*/
short getShort(int columnIndex);
/**
* Returns the value of the requested column as an int.
*
* <p>If the native content of that column is not numeric the result will be
* the result of passing the column value to Integer.valueOf(x).
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as an int.
*/
int getInt(int columnIndex);
/**
* Returns the value of the requested column as a long.
*
* <p>If the native content of that column is not numeric the result will be
* the result of passing the column value to Long.valueOf(x).
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as a long.
*/
long getLong(int columnIndex);
/**
* Returns the value of the requested column as a float.
*
* <p>If the native content of that column is not numeric the result will be
* the result of passing the column value to Float.valueOf(x).
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as a float.
*/
float getFloat(int columnIndex);
/**
* Returns the value of the requested column as a double.
*
* <p>If the native content of that column is not numeric the result will be
* the result of passing the column value to Double.valueOf(x).
*
* @param columnIndex the zero-based index of the target column.
* @return the value of that column as a double.
*/
double getDouble(int columnIndex);
/**
* Returns <code>true</code> if the value in the indicated column is null.
*
* @param columnIndex the zero-based index of the target column.
* @return whether the column value is null.
*/
boolean isNull(int columnIndex);
/**
* Returns <code>true</code> if the cursor supports updates.
*
* @return whether the cursor supports updates.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean supportsUpdates();
/**
* Returns <code>true</code> if there are pending updates that have not yet been committed.
*
* @return <code>true</code> if there are pending updates that have not yet been committed.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean hasUpdates();
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateBlob(int columnIndex, byte[] value);
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateString(int columnIndex, String value);
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateShort(int columnIndex, short value);
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateInt(int columnIndex, int value);
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateLong(int columnIndex, long value);
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateFloat(int columnIndex, float value);
/**
* Updates the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @param value the new value.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateDouble(int columnIndex, double value);
/**
* Removes the value for the given column in the row the cursor is
* currently pointing at. Updates are not committed to the backing store
* until {@link #commitUpdates()} is called.
*
* @param columnIndex the zero-based index of the target column.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean updateToNull(int columnIndex);
/**
* Atomically commits all updates to the backing store. After completion,
* this method leaves the data in an inconsistent state and you should call
* {@link #requery} before reading data from the cursor again.
*
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean commitUpdates();
/**
* Atomically commits all updates to the backing store, as well as the
* updates included in values. After completion,
* this method leaves the data in an inconsistent state and you should call
* {@link #requery} before reading data from the cursor again.
*
* @param values A map from row IDs to Maps associating column names with
* updated values. A null value indicates the field should be
removed.
* @return whether the operation succeeded.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
boolean commitUpdates(Map<? extends Long,
? extends Map<String,Object>> values);
/**
* Reverts all updates made to the cursor since the last call to
* commitUpdates.
* @hide
* @deprecated use the {@link ContentResolver} update methods instead of the Cursor
* update methods
*/
@Deprecated
void abortUpdates();
/**
* Deactivates the Cursor, making all calls on it fail until {@link #requery} is called.
* Inactive Cursors use fewer resources than active Cursors.
* Calling {@link #requery} will make the cursor active again.
*/
void deactivate();
/**
* Performs the query that created the cursor again, refreshing its
* contents. This may be done at any time, including after a call to {@link
* #deactivate}.
*
* @return true if the requery succeeded, false if not, in which case the
* cursor becomes invalid.
*/
boolean requery();
/**
* Closes the Cursor, releasing all of its resources and making it completely invalid.
* Unlike {@link #deactivate()} a call to {@link #requery()} will not make the Cursor valid
* again.
*/
void close();
/**
* return true if the cursor is closed
* @return true if the cursor is closed.
*/
boolean isClosed();
/**
* Register an observer that is called when changes happen to the content backing this cursor.
* Typically the data set won't change until {@link #requery()} is called.
*
* @param observer the object that gets notified when the content backing the cursor changes.
* @see #unregisterContentObserver(ContentObserver)
*/
void registerContentObserver(ContentObserver observer);
/**
* Unregister an observer that has previously been registered with this
* cursor via {@link #registerContentObserver}.
*
* @param observer the object to unregister.
* @see #registerContentObserver(ContentObserver)
*/
void unregisterContentObserver(ContentObserver 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
* {@link #requery()}, {@link #deactivate()}, or {@link #close()}.
*
* @param observer the object that gets notified when the cursors data set changes.
* @see #unregisterDataSetObserver(DataSetObserver)
*/
void registerDataSetObserver(DataSetObserver observer);
/**
* Unregister an observer that has previously been registered with this
* cursor via {@link #registerContentObserver}.
*
* @param observer the object to unregister.
* @see #registerDataSetObserver(DataSetObserver)
*/
void unregisterDataSetObserver(DataSetObserver observer);
/**
* 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.
*
* @param cr The content resolver from the caller's context. The listener attached to
* this resolver will be notified.
* @param uri The content URI to watch.
*/
void setNotificationUri(ContentResolver cr, Uri uri);
/**
* onMove() will only be called across processes if this method returns true.
* @return whether all cursor movement should result in a call to onMove().
*/
boolean getWantsAllOnMoveCalls();
/**
* 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.
*
* <p>These values may only change when requery is called.
* @return cursor-defined values, or Bundle.EMTPY if there are no values. Never null.
*/
Bundle getExtras();
/**
* This is an out-of-band way for the the user of a cursor to communicate with the cursor. The
* structure of each bundle is entirely defined by the cursor.
*
* <p>One use of this is to tell a cursor that it should retry its network request after it
* reported an error.
* @param extras extra values, or Bundle.EMTPY. Never null.
* @return extra values, or Bundle.EMTPY. Never null.
*/
Bundle respond(Bundle extras);
}