与每个循环相关的ArrayIndexOutOfBoundsException

I am a beginner and I am building a classical Nim game. So far, I've made the functions of adding and removing players. Now, I want to display the players, but bumped into this ArrayIndexOutOfBoundsException. I've checked this article, but couldn't find what's wrong with my code. For-Each Loop Java Error ArrayIndexOutOfBoundsException

Basically, I grab the information using getters from NimPlayer, and I use each loop to print out players. I've checked the loop's length, but it doesn't work.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1 at Nimsys.processCommands(Nimsys.java:35) at Nimsys.main(Nimsys.java:12)

  1. line 12 refers to processCommands.
  2. line 35 is the displayPlayer() function in processCommands.

非常感谢您的帮助,感谢您的友好和耐心。

Here is part of my Nimsys:

public class Nimsys {

private NimModel nimModel;

public static void main(String[] args) {
    Nimsys nimsys = new Nimsys();
    nimsys.processCommands();
}


Scanner in = new Scanner(System.in);

private void processCommands() {
    this.nimModel = new NimModel();
    System.out.println("Welcome to Nim\n");
    while (true) {
        System.out.print('$');
        String [] commandin = in.nextLine().split(" ");

        if (commandin[0].equalsIgnoreCase("displayplayer")) {
            displayPlayer(commandin[1]);
    }
}
private void displayPlayer(String userName) {
    if (!userName.isEmpty()) {
        nimModel.displayCertainPlayer(userName);
        return;
    } else {
        nimModel.displayAllPlayers();
        return;
    }
}

part of my NimModel:

public void displayCertainPlayer(String inputUser) {
    if (inputUser != null && playerList.size() != 0 ) {
        for (NimPlayer player : playerList) {
            String userCheck = player.getUserName();
            String userName = player.getUserName();
            String familyName = player.getFamilyName();
            String givenName= player.getGivenName();
            int gamesWon = player.getGamesWon();
            int gamesPlayed = player.getGamesPlayed();

            if (userCheck.equals(userName)) {
                System.out.println(userName + "," + familyName + "," + givenName + "," + gamesPlayed + " games," + gamesWon + " wins");
            } else {
                System.out.println("The player does not exist");
            }          
        }
    } 
}

public void displayAllPlayers() {
    if (playerList.size() != 0) {
        for (NimPlayer player : playerList) {
            String userName = player.getUserName();
            String familyName = player.getFamilyName();
            String givenName= player.getGivenName();
            int gamesWon = player.getGamesWon();
            int gamesPlayed = player.getGamesPlayed();

            System.out.println(userName + "," + familyName + "," + givenName + "," + gamesPlayed + " games," + gamesWon + " wins");
        }
    } else {
        System.out.println("There is no players.");
    }

}

part of NimPlayer:

ublic class NimPlayer {


private final String userName;
private String familyName;
private String givenName;

private int gamesPlayed;
private int gamesWon;
private int winRatio;



public NimPlayer(String userName, String familyName, String givenName) {

    this.userName = userName;
    this.familyName = familyName;
    this.givenName = givenName;
    this.gamesPlayed = 0;
    this.gamesWon = 0;
}
// getters and setters
}