java,Stream,filter,sorted,map用法

import .*;

import ;

class User {

private Integer age;

private String name;

public User(Integer age, String name) {

this.age = age;

this.name = name;

}

public String getName() {

return name;

}

public Integer getAge() {

return age;

}

@Override

public String toString() {

return "User{" +

"age=" + age +

", name='" + name + '\'' +

'}';

}

}

public class Main {

public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException {

List<User> userList = new ArrayList<>();

(new User(3, "Tom"));

(new User(2, "Ana"));

(new User(99, "Bob"));

(new User(1, "Lyly"));

(new User(4, "Lyly"));

// 正确,对象映射成名字

// List<String> nameList = ().map(User::getName).collect(());//[Tom, Ana, Bob, Lyly, Lyly]

// 正确,对象映射成名字

List<String> nameList = ().map(user -> ()).collect(());//[Tom, Ana, Bob, Lyly, Lyly]

//错误

List<String> nameList = ().forEach(user -> ()).collect(());

(nameList);

}

}