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

        User user1 = new User("第一位","用户1");

        list.add(user1);

        User user2 = new User("第二位","用户2");

        list.add(user2);

        User user3 = new User("第三位","用户3");

        list.add(user3);

        List<String> tableNames=list.stream().map(User::getMessage).collect(Collectors.toList());

        System.out.println("输出第一个："+tableNames);

        List<String> orders=list.stream().map(User::getOrder).collect(Collectors.toList());

        System.out.println(orders)

输出第一个：[用户1, 用户2, 用户3]

[第一位, 第二位, 第三位]

public class User {

     String order;

     String message;

     public User(String order, String message) {

        this.order = order;

        this.message = message;

    }

    public String getOrder() {

        return order;

    }

    public void setOrder(String order) {

        this.order = order;

    }

    public String getMessage() {

        return message;

    }

    public void setMessage(String message) {

        this.message = message;

    }

}