| /* |
| * 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; |
| |
| /** |
| * A convience 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. |
| */ |
| public class MergeCursor extends AbstractCursor |
| { |
| private DataSetObserver mObserver = new DataSetObserver() { |
| |
| @Override |
| public void onChanged() { |
| // Reset our position so the optimizations in move-related code |
| // don't screw us over |
| mPos = -1; |
| } |
| |
| @Override |
| public void onInvalidated() { |
| mPos = -1; |
| } |
| }; |
| |
| public MergeCursor(Cursor[] cursors) |
| { |
| mCursors = cursors; |
| mCursor = cursors[0]; |
| |
| for (int i = 0; i < mCursors.length; i++) { |
| if (mCursors[i] == null) continue; |
| |
| mCursors[i].registerDataSetObserver(mObserver); |
| } |
| } |
| |
| @Override |
| public int getCount() |
| { |
| int count = 0; |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| count += mCursors[i].getCount(); |
| } |
| } |
| return count; |
| } |
| |
| @Override |
| public boolean onMove(int oldPosition, int newPosition) |
| { |
| /* Find the right cursor */ |
| mCursor = null; |
| int cursorStartPos = 0; |
| int length = mCursors.length; |
| for (int i = 0 ; i < length; i++) { |
| if (mCursors[i] == null) { |
| continue; |
| } |
| |
| if (newPosition < (cursorStartPos + mCursors[i].getCount())) { |
| mCursor = mCursors[i]; |
| break; |
| } |
| |
| cursorStartPos += mCursors[i].getCount(); |
| } |
| |
| /* Move it to the right position */ |
| if (mCursor != null) { |
| boolean ret = mCursor.moveToPosition(newPosition - cursorStartPos); |
| return ret; |
| } |
| return false; |
| } |
| |
| @Override |
| public String getString(int column) |
| { |
| return mCursor.getString(column); |
| } |
| |
| @Override |
| public short getShort(int column) |
| { |
| return mCursor.getShort(column); |
| } |
| |
| @Override |
| public int getInt(int column) |
| { |
| return mCursor.getInt(column); |
| } |
| |
| @Override |
| public long getLong(int column) |
| { |
| return mCursor.getLong(column); |
| } |
| |
| @Override |
| public float getFloat(int column) |
| { |
| return mCursor.getFloat(column); |
| } |
| |
| @Override |
| public double getDouble(int column) |
| { |
| return mCursor.getDouble(column); |
| } |
| |
| @Override |
| public int getType(int column) { |
| return mCursor.getType(column); |
| } |
| |
| @Override |
| public boolean isNull(int column) |
| { |
| return mCursor.isNull(column); |
| } |
| |
| @Override |
| public byte[] getBlob(int column) |
| { |
| return mCursor.getBlob(column); |
| } |
| |
| @Override |
| public String[] getColumnNames() |
| { |
| if (mCursor != null) { |
| return mCursor.getColumnNames(); |
| } else { |
| return new String[0]; |
| } |
| } |
| |
| @Override |
| public void deactivate() |
| { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].deactivate(); |
| } |
| } |
| super.deactivate(); |
| } |
| |
| @Override |
| public void close() { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] == null) continue; |
| mCursors[i].close(); |
| } |
| super.close(); |
| } |
| |
| @Override |
| public void registerContentObserver(ContentObserver observer) { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].registerContentObserver(observer); |
| } |
| } |
| } |
| @Override |
| public void unregisterContentObserver(ContentObserver observer) { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].unregisterContentObserver(observer); |
| } |
| } |
| } |
| |
| @Override |
| public void registerDataSetObserver(DataSetObserver observer) { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].registerDataSetObserver(observer); |
| } |
| } |
| } |
| |
| @Override |
| public void unregisterDataSetObserver(DataSetObserver observer) { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].unregisterDataSetObserver(observer); |
| } |
| } |
| } |
| |
| @Override |
| public boolean requery() |
| { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] == null) { |
| continue; |
| } |
| |
| if (mCursors[i].requery() == false) { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| private Cursor mCursor; // updated in onMove |
| private Cursor[] mCursors; |
| } |