类 main 的方法未定义

Question

我正在编写一个简单的社交媒体模型，其中用户的朋友表示为一组Friend对象。使用toStringFriendsmain 方法中使用的方法时，我收到了标题错误。有谁知道如何解决这个问题？public class Friend {private String name;private String password;private int uid;private Friend [] friends;public Friend (String name, String password, int uid, Friend [] friends) {    this.name = name;    this.password = password;    this.uid = uid;    this.friends [0] = friends [0];}public Friend [] getFriends () {    return friends;}public String toStringFriends (Friend [] friends) {         String s = "";      for (int i = 0; i <= friends.length; i++) {         s = s + (friends [i]).getName();    }    return s;}}public class Main {public static void main(String[] args) {    Friend [] noFriends = new Friend [0];    Friend [] laurasFriends = new Friend [1];               Friend jack = new Friend ("jack","liverpool",1,noFriends);      laurasFriends [0] = jack;    Friend laura = new Friend ("laura","everton",2,laurasFriends);    String s = toStringFriends(laurasFriends);    System.out.println(s);      System.out.println(toStringFriends(laura.getFriends()));}}

Answer 1

要么toStringFriends()静态要么实例化一个 Friend 对象并在其上调用该方法。

Answer 2

您不能在没有对象的情况下调用实例或非静态方法。您应该使用一些实例对象，然后您可以通过.运算符调用。喜欢object.method()

Answer 3

您需要从laura对象的实例中调用它：

String s = laura.toStringFriends(laurasFriends);