How to use concat to get different object lists in Java 8

I have two Java classes

class A {
 String name;
 List<B> numbers;
}

class B {
 Integer number;
}

I want to get the uniqueness of class A and connect the list of B

For example, suppose I have a list containing the following objects

List<A>{
 name = "abc"
 List<B>{1,2}

 name= "xyz"
 List<B>{3,4}

 name = "abc"
 List<B>{3,5}
}

The result should be:

List<A>{
 name = "abc"
 List<B>{1,2,3,5}

 name="xyz"
 List<B>{3,4}
}

Any help will be greatly appreciated

Note: I want to use Java 8 streams to achieve this

thank you

Solution

You can use the tomap collector:

Collection<A> result = list.stream()
         .collect(Collectors.toMap(a -> a.name,a -> a,(a,b) -> {a.numbers.addAll(b.numbers); return a;}))
         .values();

You can copy the results to the list (such as the new ArrayList < > (results)), but since we do not keep any specific order, using the list is not very useful In most cases, the collection results are good