Adding rows into Cursor manually

Question

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 numbers that are not saved before to the contact database. For example;

• 3333333 -> Tim
• 5555555 -> Jim
• 1111111 -> unknown

I have the array containing the phone numbers shown above, namely phoneArr.

int size=phoneArr.size();
if(size>0){
        Cursor[] cursors=new Cursor[size];
        for(int i=0;i<size;i++){
            Uri contactUri1 = Uri.withAppendedPath(ContactsContract.PhoneLookup.CONTENT_FILTER_URI, Uri.encode(phoneArr.get(i)));
            cursors[i] = getContentResolver().query(contactUri1, PEOPLE_PROJECTION, null, null, " _id asc limit 1");
        }
        Cursor phones=new MergeCursor(cursors);

phones.getCount() returns 2 in the above scenario. When the phone number does not appear in the contact list the cursor becomes empty and somehow when I merge them it doesn't contribute anything at all. What I want is to have a cursor as follows

Cursor phones -> {Tim, Jim, 1111111}

I think I can do this by adding the row manually as follows:

Uri contactUri1 = Uri.withAppendedPath(ContactsContract.PhoneLookup.CONTENT_FILTER_URI, Uri.encode(phoneArr.get(i)));
cursors[i] = getContentResolver().query(contactUri1, PEOPLE_PROJECTION, null, null, " _id asc limit 1");
if(cursors[i].getCount()==0)
    // add the phone number manually to the cursor

How can I achieve this?

Here is the PEOPLE_PROJECTION

private static final String[] PEOPLE_PROJECTION = new String[] {
    ContactsContract.PhoneLookup._ID,
    ContactsContract.PhoneLookup.DISPLAY_NAME,
    ContactsContract.PhoneLookup.NUMBER
};

Answer 1

Easiest way to add rows in a cursor is to use a MatrixCursor and a MergeCursor. Those two classes are from the SDK and here to solve that kind of problems.

Basically what you do is :

1. Put the rows you want to add in a MatrixCusror
2. Merge your cursor and your matrixCursor using a MergeCursor

Something like:

// Create a MatrixCursor filled with the rows you want to add.
MatrixCursor matrixCursor = new MatrixCursor(new String[] { colName1, colName2 });
matrixCursor.addRow(new Object[] { value1, value2 });

// Merge your existing cursor with the matrixCursor you created.
MergeCursor mergeCursor = new MergeCursor(new Cursor[] { matrixCursor, cursor });

// Use your the mergeCursor as you would use your cursor.

Answer 2

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.