Android : Need to get data from two classes using parse.com in android

I have two classes in parse.com. The first class contains two string values which are unique for each row. The second class contains multiple values, including the categorynames however in class 2 these categorynames are not unique. What I need is to populate a listview with the data from class one and where string1, which contains categorynames, from class one equals string1 from class two, which also contains categorynames, I need to get the values from string2 in class2 and the values in string2 which are numbers need to be added to each other where string1 is equal.

So how do i populate a listview with 3 values from two classes? And how can aggregate the values from a class where the category values are equal?