Create a list from instance variables of items in array using streams

Question

I have an array of items, and I want to create a list (or any iterable) from an instance variable belonging to them.

public void foo(final MyClass... args) {
    final List<Baz> properties = new ArrayList<>();
    for (final MyClass a : args) {
        properties.add(a.getProperty());
    }
}

How would I do this using a one-liner stream?

So an instance of `MyClass` has a property of type `MyClass`? Am I getting this right? — deHaar, Jul 02 '20 at 12:20
Fixed both, wrote this without compiling it and I jump between programming languages — Michael Bianconi, Jul 02 '20 at 12:24
`Arrays.stream(args).map(MyClass::getProperty).collect(Colectors.toList());` ? — Eritrean, Jul 02 '20 at 12:30

score 3 · Accepted Answer · answered Jul 02 '20 at 12:31

3

List<Baz> list = Arrays.stream(args).map(MyClass::getProperty).collect(Collectors.toList());
Iterable<Baz> iterable = () -> Arrays.stream(args).map(MyClass::getProperty).iterator();

answered Jul 02 '20 at 12:31

score 0 · Answer 2 · answered Jul 02 '20 at 12:32

0

Assuming that getProperty() method of MyClass returns an object of type Baz

List<Baz> properties = Stream.of(args)
.map(myClazz -> myClazz.getProperty())
.collect(Collectors.toList())

answered Jul 02 '20 at 12:32

Shyam Baitmangalkar

1,075
12
18

Create a list from instance variables of items in array using streams

2 Answers2