我的目标:以优雅的 Java-8 方式从 LinkedList
中提取 User
的用户名并生成一个 LinkedList
。
public static void main(String[] args) {
LinkedList<User> users = new LinkedList<>();
users.add(new User(1, "User1"));
users.add(new User(2, "User2"));
users.add(new User(3, "User3"));
// Vanilla Java approach
LinkedList<String> usernames = new LinkedList<>();
for(User user : users) {
System.out.println(user.getUsername());
usernames.add(user.getUsername());
}
System.out.println("Usernames = " + usernames.toString());
// Java 8 approach
users.forEach((user) -> System.out.println(user.getUsername()));
LinkedList<String> usernames2 = users.stream().map(User::getUsername). // Is there a way to turn this map into a LinkedList?
System.out.println("Usernames = " + usernames2.toString());
}
static class User {
int id;
String username;
public User() {
}
public User(int id, String username) {
this.id = id;
this.username = username;
}
public void setUsername(String username) {
this.username = username;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public int getId() {
return id;
}
}
我卡在了将Stream
对象转换为LinkedList
上。我可以先将其转换为数组 (Stream::toArray()
),再将该数组转换为List
(Arrays.asList(Stream::toArray())
),但这种方式似乎不太好用,谢绝此方法。
我是否漏掉了什么?