How to get the Max value SQLite Android

Trying to get the maximum id in my TABLE_GOALS

public String getLatestGoal(){
    SQLiteDatabase db=dbhandler.getWritableDatabase();

    //columns
    Cursor cursor=db.query(MyDBHandler.TABLE_GOALS, null, "SELECT MAX("+MyDBHandler.COLUMN_ID+"))", null, null, null, null);
    StringBuffer buffer = new StringBuffer();
    while(cursor.moveToNext()){
        int index1=cursor.getColumnIndex(MyDBHandler.COLUMN_ID);
        String max_id=cursor.getString(index1);
        buffer.append(max_id);
    }
    return buffer.toString();

}

I can't get the maximum value and i don't know why. Sorry, newbie here in Android.