Java8从对象列表中取出某个属性的列表详解编程语言

List<属性值类型> 属性List = 对象List.stream().map(对象::get方法()).collect(Collectors.toList());

List<Integer> idList = list.stream().map(User::getId).collect(Collectors.toList()); 
 
//或者 
List<Integer> idList = list.stream().map(u -> u.getId()).collect(Collectors.toList());

public class HelloWorld { 
 
    public static void main(String[] args) { 
        List<User> list = new ArrayList<>(); 
        for(int i=1;i<=10;i++) { 
            User u = new User(i, "用户-" + i); 
            list.add(u); 
        } 
        //取出id列表 
        //List<Integer> idList = list.stream().map(User::getId).collect(Collectors.toList()); 
        List<Integer> idList = list.stream().map(u -> u.getId()).collect(Collectors.toList()); 
 
        System.out.println("id列表：" + idList); 
    } 
    private static class User{ 
        int id; 
        String name; 
 
        public User(int id, String name) { 
            this.id = id; 
            this.name = name; 
        } 
 
        public int getId() { 
            return id; 
        } 
 
        public void setId(int id) { 
            this.id = id; 
        } 
 
        public String getName() { 
            return name; 
        } 
 
        public void setName(String name) { 
            this.name = name; 
        } 
 
        @Override 
        public String toString() { 
            return "User{" + 
                    "id=" + id + 
                    ", name='" + name + '/'' + 
                    '}'; 
        } 
    } 
 
}