Adding rows into Cursor manually

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無奈伤痛
無奈伤痛 2020-12-03 13:47

I have an array of phone numbers and I want to get the corresponding contact names from the contacts database.

In the array of phone numbers, I also have some number

4条回答
  •  轻奢々
    轻奢々 (楼主)
    2020-12-03 14:34

    I use a solution that does the trick for all my different needs, and which is simpler than implementing Cursor.
    Here is an example where I have to add extra "playlist" rows to a Cursor, retrieved from the Mediastore. I add rows at first indexes of the original Cursor :

    public class CursorWithExtraPlaylists extends CursorWrapper {
    
    public static final int ID_COLUMN_INDEX = 0;
    public static final int NAME_COLUMN_INDEX = 1;
    
    private int mPos = -1;
    private Context mContext;
    private Playlist[] extras;
    
    public CursorWithExtraPlaylists(Cursor cursor, Context context,
            Playlist[] extras) {
        super(cursor);
        mContext = context;
        this.extras = extras;
    }
    
    @Override
    public int getCount() {
        return super.getCount() + extras.length;
    }
    
    @Override
    public int getPosition() {
        return mPos;
    }
    
    @Override
    public boolean moveToFirst() {
        return moveToPosition(0);
    }
    
    @Override
    public boolean moveToLast() {
        return moveToPosition(getCount() - extras.length);
    }
    
    @Override
    public boolean move(int offset) {
        return moveToPosition(mPos + offset);
    }
    
    @Override
    public boolean moveToPosition(int position) {
        // Make sure position isn't past the end of the cursor
        final int count = getCount();
        if (position >= count) {
            mPos = count;
            return false;
        }
        // Make sure position isn't before the beginning of the cursor
        if (position < 0) {
            mPos = -1;
            return false;
        }
        // Check for no-op moves, and skip the rest of the work for them
        if (position == mPos) {
            return true;
        }
    
        mPos = position;
        if (mPos > 0) {
            // ok, that concerns super cursor
            return super.moveToPosition(mPos - 1);
        }
        return true;
    }
    
    @Override
    public boolean moveToNext() {
        return moveToPosition(mPos + 1);
    }
    
    @Override
    public boolean moveToPrevious() {
        return moveToPosition(mPos - 1);
    }
    
    private boolean isPointingOnExtras() {
        if (-1 == mPos || getCount() == mPos) {
            throw new CursorIndexOutOfBoundsException(mPos, getCount());
        }
        if (mPos <= extras.length - 1) {
            // this is a request on an extra value
            return true;
        }
        return false;
    }
    
    private Object getExtraValue(int columnIndex) {
        switch (columnIndex) {
        case ID_COLUMN_INDEX:
            return extras[mPos].getId();
        case NAME_COLUMN_INDEX:
            return extras[mPos].getName(mContext);
        }
        return null;
    }
    
    @Override
    public int getInt(int columnIndex) {
        if (isPointingOnExtras())
            return (Integer) getExtraValue(columnIndex);
        int res = super.getInt(columnIndex);
        return res;
    }
    
    @Override
    public String getString(int columnIndex) {
    
        if (isPointingOnExtras())
            return getExtraValue(columnIndex).toString();
        return super.getString(columnIndex);
    }
    
    public static class Playlist {
        private int mId;
        private int mNameResId;
    
        public Playlist(int mId, int nameResId) {
            this.mId = mId;
            this.mNameResId = nameResId;
        }
    
        public int getId() {
            return mId;
        }
    
        public String getName(Context mContext) {
            return mContext.getResources().getString(mNameResId);
        }
    
    }
    }
    

    Original cursor has 2 columns (int,String), so I construct it with an array of extra rows objects.

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