Enumerable.Select 与 C# 中的 lambdas 的 Java 等价物是什么？

Question

Say I have an object in C#:

public class Person
{
    public string Name{get;set;}
    public int Age{get;set;}
}

To select the names from this list in C# I would do the following:

List<string> names = person.Select(x=>x.Name).ToList();

How would I do the same thing in Java 8?

Answer 1

If you have a list of Persons like List<Person> persons; you can say

List<String> names
  =persons.stream().map(x->x.getName()).collect(Collectors.toList());

or, alternatively

List<String> names
  =persons.stream().map(Person::getName).collect(Collectors.toList());

But collecting into a List or other Collection is intented to be used with legacy APIs only where you need such a Collection . Otherwise you would proceed using the stream's operations as you can do everything you could do with a Collection and a lot more without the need for an intermediate storage of the String s, eg

persons.stream().map(Person::getName).forEach(System.out::println);