Java Pokemon 程序 --> 删除 map 条目时出现并发修改异常

Question

这个问题已经有答案了:

Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop (31 个回答)

已关闭 5 年前。

我正在编写一个简单的类似 Pokemon 的程序，但是当用户指定他们想要在团队中加入多少 Pokemon 时，我遇到了一个问题。用户的团队拥有 Pokemon 名称和 Pokemon 对象本身的 map 。

当游戏开始时，用户指定他们想要加入团队的神奇宝贝数量。有 6 个 Pokemon 的预制阵列。默认的 Pokemon 构造函数将名称分配给 2e14 和 -2e14 之间的随机 double 值。然后，for 循环将指定数量的 Pokemon 对象添加到用户的团队中，并询问每个对象的统计信息。询问统计数据的循环应该，对于每个条目，将其删除并放回到具有与输入的神奇宝贝名称相对应的 key 的条目中。

我目前遇到以下问题:- 并发修改异常

编辑:已解决。相反，我使用预先制作的可能的口袋妖怪数组中的对象获取统计数据，然后一旦它们有了统计数据，将它们添加到团队中，这样我就不必更改 key 。这是有问题的代码:

// for every Pokemon on the user's team, get the stats for them.
    // Logic:
    /* The for loop goes through the Map. For each entry, it saves the name of the pokemon
     * and the pokemon itself, because if you don't, the key is just a random double, so 
     * the user can't call its name. This goes through and removes those entries,
     * then re - inserts them back into the team, but this time the key corresponds to its name  */
    for(Map.Entry<String, Pokemon> entry : userTeam.team.entrySet()) {
        // if the pokemon hasn't already gone through this procedure,
        if(!entry.getValue().hasBeenStats) {
            entry.getValue().getStats(input);
            Pokemon pok = entry.getValue();
            userTeam.team.remove(entry.getKey());   
            userTeam.addPokemon(pok);
        }

    }

如果您需要，这里有一些额外的代码片段:

public class PokemonGame {
int userTeamSize;
PokemonTeam userTeam = new PokemonTeam();

// potential pokemon
Pokemon pok1 = new Pokemon();
Pokemon pok2 = new Pokemon();
Pokemon pok3 = new Pokemon();
Pokemon pok4 = new Pokemon();
Pokemon pok5 = new Pokemon();
Pokemon pok6 = new Pokemon();

                                // 0    1      2     3     4     5
Pokemon[] potentialUserPokemons = {pok1, pok2, pok3, pok4, pok5, pok6};

以下方法应该接收一个数字，该数字将成为 teamSize，然后将该数量的 Pokemon 从数组添加到用户的团队中:

private void getUserSettings(Scanner input, PokemonTeam team) {
    System.out.println("How many Pokemon do you want on your team?");

    while(true) {
    try {
        int tempInt = Integer.parseInt(input.next());
        if((tempInt > 6) || (tempInt < 1) ) {
            System.out.println("Error: Enter valid team length.");
            continue;
        } else {
            userTeamSize = tempInt;
        }
        break;
    } catch(NumberFormatException e) {
        System.out.println("Error: Try again");
        continue;
    }
    }
    input.nextLine();
}

private void setUpUserTeam(Scanner input) {
    /* adds every Pokemon for the specified length into the users team, from the
    * potential team array*/
    for(int num = 0; num < userTeamSize; num++) {
        userTeam.addPokemon(potentialUserPokemons[num]);
    }
    // for every Pokemon on the user's team, get the stats for them.
    // Logic:
    /* The for loop goes through the Map. For each entry, it saves the name of the pokemon
     * and the pokemon itself, because if you don't, the key is just a random double, so 
     * the user can't call its name. This goes through and removes those entries,
     * then re - inserts them back into the team, but this time the key corresponds to its name  */
    // this part is not working, it only run once
    for(Map.Entry<String, Pokemon> entry : userTeam.team.entrySet()) {
        // if the pokemon hasn't already gone through this procedure,
            entry.getValue().getStats(input);
            // save it's name --> key, and object --> pokemon for the value
            String pokName = entry.getValue().getName();
            Pokemon pok = entry.getValue();
            userTeam.team.put(pokName, pok );
            userTeam.team.remove(entry.getKey());   
    }

    System.out.println("Pick a Pokemon to start with: ");
    String pickedPokemon = input.nextLine();
    // goes through the user's team, finds the Pokemon they specified, and sets it as the current pokemon
    outerloop:
    while (true) {
        for(Map.Entry<String, Pokemon> entry : userTeam.team.entrySet()) {
            if(entry.getKey().equals(pickedPokemon)) {
                userTeam.setCurrentPokemon(entry.getValue());
                break outerloop;
            } 
        }
        System.out.println("Error: Pokemon not found. Try again.");
    }
}

在 PokemonTeam 中，有一个 Map 和一个向其中添加 Pokemon 的方法:

Map<String, Pokemon> team = new HashMap<String, Pokemon>();
public void addPokemon(Pokemon pokemon) {
    team.put(pokemon.getName(), pokemon);
    /*teamSize is a different variable in PokemonTeam and once the 
    * Pokemons are added to the Map, will be the same as userTeamSize
    * in class PokemonGame*/
    teamSize = team.size();
}

这是 Pokemon 类中的 getStats():

public void getStats(Scanner theInput) {
    System.out.println("Please enter the stats of your pokemon: ");
    System.out.println("Name: ");
    // set the pokemon's name as what they enter
    this.setName(theInput.nextLine());
    // error handling
    System.out.println("Level: ");
    while(true) {
    // if there is a wrong type entered it will repeat until correct
    try {
        this.setLevel(Integer.parseInt(theInput.next()));
    } catch(NumberFormatException e) {
        System.out.println("Error: Please try again.");
        continue;
    }
    break;
    }

    System.out.println("Attack: "); 
    while(true) {
        try {
            this.setAttack(Integer.parseInt(theInput.next()));
        } catch(NumberFormatException e) {
            System.out.println("Error: Please try again.");
            continue;
        }
        break;
    }

    System.out.println("Defense: ");
    while(true) {
        try {
            this.setDefense(Integer.parseInt(theInput.next()));
        } catch(NumberFormatException e) {
            System.out.println("Error: Please try again.");
            continue;
        }
        break;
    }

    System.out.println("Base: "); 
    while(true) {
        try {
            this.setBase(Integer.parseInt(theInput.next()));
        } catch(NumberFormatException e) {
            System.out.println("Error: Please try again.");
            continue;
        }
        break;
    }

    System.out.println("STAB: "); 
    while(true) {
        try {
            this.setSTAB(Integer.parseInt(theInput.next()));
        } catch(NumberFormatException e) {
            System.out.println("Error: Please try again.");
            continue;
        }
        break;
    }

    System.out.println("HP: ");
    while(true) {
        try {
            int userHP = Integer.parseInt(theInput.next());
            this.setMaxHP(userHP);
            this.setCurrentHP(userHP);
            this.setDamageAuto();
        } catch(NumberFormatException e) {
            System.out.println("Error: Please try again.");
            continue;
        }
        break;
    }
    // gets the names of the moves and adds them to the map of moves and move infos
    theInput.nextLine();
    System.out.println("Name your Pokemon's 4 moves: ");
    String moveNameOne = theInput.nextLine();
    moves.put(moveNameOne, generateMoveInfo(moveNameOne));
    String moveNameTwo = theInput.nextLine();
    moves.put(moveNameTwo, generateMoveInfo(moveNameTwo));
    String moveNameThree = theInput.nextLine();
    moves.put(moveNameThree, generateMoveInfo(moveNameThree));
    String moveNameFour = theInput.nextLine();
    moves.put(moveNameFour, generateMoveInfo(moveNameFour));
    hasBeenStats = true;
}

Answer 1

除非您更改 pickedPokemon 的值，否则将打印 Error: Pokemon not find。再试一次。永远。

while (true) {
    for(Map.Entry<String, Pokemon> entry : userTeam.team.entrySet()) {
        if(entry.getKey().equals(pickedPokemon)) {
            userTeam.setCurrentPokemon(entry.getValue());
            break outerloop;
        }
    }
    System.out.println("Error: Pokemon not found. Try again.");
}