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Diffstat (limited to 'core/java/android/database/MergeCursor.java')
| -rw-r--r-- | core/java/android/database/MergeCursor.java | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/core/java/android/database/MergeCursor.java b/core/java/android/database/MergeCursor.java new file mode 100644 index 0000000..7e91159 --- /dev/null +++ b/core/java/android/database/MergeCursor.java @@ -0,0 +1,257 @@ +/* + * 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; + } + + /** + * @hide + * @deprecated + */ + @Override + public boolean deleteRow() + { + return mCursor.deleteRow(); + } + + /** + * @hide + * @deprecated + */ + @Override + public boolean commitUpdates() { + int length = mCursors.length; + for (int i = 0 ; i < length ; i++) { + if (mCursors[i] != null) { + mCursors[i].commitUpdates(); + } + } + onChange(true); + return true; + } + + @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 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(); + } + } + } + + @Override + public void close() { + int length = mCursors.length; + for (int i = 0 ; i < length ; i++) { + if (mCursors[i] == null) continue; + mCursors[i].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; +} |