游戏背景： 假设需要创建一个模拟五人组队游戏的框架

主代码

package www.heima;

import com.sun.xml.internal.ws.policy.privateutil.PolicyUtils;

import java.io.*;
import java.time.chrono.HijrahEra;
import java.util.ArrayList;
import java.util.Scanner;
/*
*
 * @aothor cds
 * @create 2019/3/31 - 9:07
*/

public class Game5Persion {
    private static ArrayList<hero> heroArrayList;

    public static void main(String[] args) throws IOException {
        //1.创建一个集合，用来存储五个英雄
        ArrayList<hero> HeroList = new ArrayList<>();

//        2.读文件，把数据加载到内存中
        loadFriends(HeroList);

//        3.判断内容是不是新的
        boolean isNew = HeroList.isEmpty();
        System.out.println("判断有没有好友:" + isNew);

//        如果是新的，创建五个对象加入集合中
                if(isNew){

//            System.out.println(" 加入五个新队友 ");
            addHeros(HeroList);
        }

//        如果不是新的，无需创建，直接开始

//        4.开始游戏
        System.out.println("游戏开始");
//                输出英雄阵容，信息
        showHeros(HeroList);
        System.out.println("showFightingCapacity(HeroList) = " + showFightingCapacity(HeroList));


//        5.游戏结束

        System.out.println( "游戏结束");

//        6.判断是不是原始阵容是不是新的
//                是新的
        if(isNew) {
            saveFriends(HeroList);
            System.out.println("新阵容，加好友");
        }else {
//                 不是新的
            System.out.println(" 已经是好友，无需加好友");
        }
//        7.退出游戏
        System.out.println("\"退出游戏\" = " + "退出游戏");

    }

    //添加新英雄
    private static void addHeros(ArrayList<hero> HeroList){
        Scanner sc = new Scanner(System.in);
        for (int i = 1 ; i < 6 ; i++ ){
            System.out.println("添加第" + i +"位新英雄：格式为String name, int attckt, String type： " );
            String line = sc.nextLine();
            String[] arr = line.split(",");
            String name = arr[0];
            int attckt = Integer.parseInt(arr[1]);
            String type = arr[2];
//            String name = sc.next();
//            int attckt = sc.nextInt();
//            String type = sc.next();
            HeroList.add(new hero(name,attckt,type));
        }

        System.out.println("组队成功 ");
    }

//    展示英雄
    public static void showHeros(ArrayList<hero> Herolist){
        int i = 1;
        for (hero heros:Herolist
             ) {
            System.out.println("heros = " + heros);
        }
    }

//    计算总攻击力
    public static int showFightingCapacity(ArrayList<hero> Herolist) {
        int num = 0;
        for (hero heros : Herolist) {
            num += heros.getAttckt();
        }
        return num;
    }

//    将好友信息写入文件
    public static void saveFriends(ArrayList<hero> heroesList) throws IOException {
        try (BufferedWriter bw = new BufferedWriter(new FileWriter("friends.txt"))) {
            for (hero heros : heroesList
            ) {
                bw.write(heros.toString());
                bw.newLine();
            }
        }
    }


    //    定义方法，读取文件，数据加载到集合中
    static void loadFriends(ArrayList<hero> heroArrayList) throws IOException {
//        Game5Persion.heroArrayList = heroArrayList;
        try (BufferedReader br = new BufferedReader(new FileReader("friends.txt"))) {
            String line;
            while ((line = br.readLine()) != null){
                String[] arr = line.split(",");
                String name = arr[0];
                int atackt = Integer.parseInt(arr[1]);
                String type = arr[2];
                heroArrayList.add(new hero(name,atackt,type));
            }
        }

    }

}

英雄类

package www.heima;

/**
 * @aothor cds
 * @create 2019/3/31 - 9:08
 */
public class hero {
    private String name;
    private int attckt;
    private String type;

    public hero() {
    }

    public hero(String name, int attckt, String type) {
        this.name = name;
        this.attckt = attckt;
        this.type = type;
    }

    public String getName() {
        return name;
    }

    public int getAttckt() {
        return attckt;
    }

    public String getType() {
        return type;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setAttckt(int attckt) {
        this.attckt = attckt;
    }

    public void setType(String type) {
        this.type = type;
    }

    @Override
    public String toString() {
        return  "name = " + name + "," + attckt + ",type = " + type;
//                "name='" + name + '\'' +
//                ", attckt=" + attckt +
//                ", type='" + type ;
    }
}

运行效果

friends.txt中没有预录信息时：

friends.txt中有预录信息时：