Java - 迭代 for 循环以创建游戏玩家并设置他们的名字

您的内部 for 循环正在迭代 players 数组，但它是空的。

也许可以试试这个：

       do {
            System.out.println("Please enter name:");
            playerName = sc.nextLine();
            if(playerName.length()!=0){
                valid = true;
                for(Player play : players)
                  if(play.getName().equalsIgnoreCase(playerName))
                     valid = false;       
                
                if(valid){
                   Player player = new Player();
                   player.setName(playerName);
                   players.add(player);
                }
            }
        } while (!valid);

我认为您可能很难进行调试，因为您的所有变量名称都非常相似。（'玩家'，'玩家'，'玩'）

编辑：更新以检查是否重复

你错过了玩家类中的一些吸气者和二传手。

Player.java

public class Player {

private String name;
    private int currentPosition;
    private double distance;
    private boolean quit;
        
    public Player() {
        // no-args constructor
    }

    public Player(String name, int currentPosition, double distance, boolean quit) {
        this.name = name;
        this.currentPosition = currentPosition;
        this.distance = distance;
        this.quit = quit;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    public int getCurrentPosition() {
        return currentPosition;
    }

    public void setCurrentPosition(int currentPosition) {
        this.currentPosition = currentPosition;
    }

    public double getDistance() {
        return distance;
    }

    public void setDistance(double distance) {
        this.distance = distance;
    }

    public boolean isQuit() {
        return quit;
    }

    public void setQuit(boolean quit) {
        this.quit = quit;
    }
}

可以按如下方式实现 SetUpGame 类。 无需创建 do-while 循环。
SetUpGame.java

import java.util.ArrayList;
import java.util.Scanner;

public class SetUpGame {
        Scanner sc = new Scanner(System.in);
        ArrayList<Player> players = new ArrayList<Player>();
        int numberOfPlayers;
        
        public int getNumberOfPlayers() {
            return numberOfPlayers;
        }

        public void setNumberOfPlayers(int numberOfPlayers) {
            this.numberOfPlayers = numberOfPlayers;
        }

        public void addPlayers() {
            System.out.print("Enter number of players: ");
            numberOfPlayers = sc.nextInt();
            
            System.out.println("What are the names of the " + numberOfPlayers + " players?");
            for(int loop = 1; loop <= numberOfPlayers; loop++) {
                Player player = new Player();
                
                System.out.print("Enter name for player " + loop + ": ");
                player.setName(sc.next());
                
                System.out.print("Enter current position for player " + loop + ": ");
                player.setCurrentPosition(sc.nextInt());
                
                System.out.print("Enter distance for player " + loop + ": ");
                player.setDistance(sc.nextDouble());
                
                System.out.print("Enter validity for player " + loop + ": ");
                player.setQuit(sc.nextBoolean());
                
                players.add(player);
            }
            sc.close();
        }
        
        public void displayAllPlayers() {
            System.out.println("Displaying all players...");
            for(Player p : players) {
                System.out.printf("%s %d %f %b", p.getName(), p.getCurrentPosition(), p.getDistance(), p.isQuit());
            }
        }
}

最后，您可以测试您的 SetUpGame 类。
TestSetUpGame.java

public class TestSetUpGame {
    public static void main(String[] args) {
        SetUpGame game = new SetUpGame();
        game.addPlayers();
        game.displayAllPlayers();
    }
}

首先，玩家列表在方法中被定义为局部变量，因此当此方法完成时，所有玩家数据都会丢失。因此，有必要修改此方法以将玩家添加到类字段或将玩家列表返回到调用方法。后一种方式是填充玩家列表的更简洁的功能方式。addPlayersSetupGame

接下来，为了有效地检测重复名称，建议创建并使用 .Set<String> playerNames

最后一个，如果打开，则不能关闭，因为在那之后不能输入任何用户输入。ScannerSystem.in

话虽如此，的代码可能如下所示：addPlayers

public List<Player> addPlayers() {
    List<Player> players = new ArrayList<>();
    Set<String> playerNames = new HashSet<>();
    Scanner sc = new Scanner(System.in);

    System.out.println("What are the names of the " + this.numberOfPlayers + " players?\n");

    for (int loop = 1; loop <= this.numberOfPlayers; loop++) {
        while (true) {
            System.out.println("Player " + loop + " please enter your name");
            String playerName = sc.nextLine();

            if (playerNames.add(playerName)) {// Set.add returns true if name was added to it
                Player p = new Player();
                p.setName(playerName);
                players.add(p);
                break; // input new player
            }
        }
    }
    return players;
}