Create 2 objects for each element of a Java stream

Question

Is there a way to create 2 different objects for each element of a stream and collect them all at last?

For example, if I have a List<String> stringList and have a class GoddClass with a default and a customConstructor, I want to create 2 objects in one stream and collect at last

stringList
  .stream()
  .map(GoddClass::new) 
  .addAnothrObject(GoddClass::customConstructor) // Not a valid line, Just to depict what is needed
  .collect(Collectors.toList());

One stream might not be the right solution to achieve what I'm trying. But the question is out for experts.

@AniketSahrawat Can you elaborate? I've used flatMap(), when I had a steam mapping resulting another stream, or similar cases, but how do you fit flatMap in this scenario — ThrowableException
– ThrowableException, Commented Jul 26, 2020 at 3:12
Create a method that returns a List<GoddClass> with both those objects accepting a string as input and use flatMap to call it like ...stream().flatMap(str -> method(str).stream()).collect.... — Naman
– Naman, Commented Jul 26, 2020 at 3:38

Unmitigated · Accepted Answer · 2020-07-26 04:02:59Z

6

.flatMap with Stream.of is most suitable in this case.

stringList
 .stream().flatMap(str -> Stream.of(new GoddClass(), new GoddClass(str))
 .collect(Collectors.toList());

answered Jul 26, 2020 at 4:02

Unmitigated

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2 Comments

ThrowableException Over a year ago

when you use above you get.Cannot infer type argument(s) for <R> flatMap(Function<? super T,? extends Stream<? extends R>>)

Unmitigated Over a year ago

@ThrowableException Could you provide a minimal, reproducible example?

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