Joining two lists in java

Question

I have lists of different classes, say A and B respectively. Definition of these classes is as follows-

class A {
 int field1;
 int field2;
}

class B {
 int field1;
 int field3;
}

class C {
 int field1;
 int field2;
 int field3;
}

I want to perform a join operation (similar to database join) on A and B, over field1 and populate the result in C.

I can iterate over the lists and do it. But, just wanted to check whether there are any library methods which does similar sort of thing.

Answer 1

If these are the only fields you're using, just iterate manually.

For larger data sets, group your data into Collections and apply a Cartesian Product algorithm .

Answer 2

You can add objects of any class to the list(if your list is not generic-specified). But when you get each object back from the list, you will not know the object is of which type.

Answer 3

Maybe by using a method in library in apache collections:

import org.apache.commons.collections.ListUtils;    

List<?> newListC = ListUtils.intersection(list1, list2);

Hope it helps.