Question

相当刚刚开始使用Java，并且刚刚开始制作地图，尝试了几天但取得了有限的成功，以便执行以下操作（代码中的注释）欢迎所有建议。理想情况下，我想从一个未填充的地图开始，用纯粹的用户输入playerName填充它，并在输入每个名称时将整数值递增1。希望这遵循所有准则！

/**
 * Constructor for objects of class player Creates player
 * objects and tests for unique player name
 */
public player() {
    Map<String, Integer> playerMap = new HashMap<>();
    System.out.println("Players in game: " + playerMap.isEmpty());
    playerMap.put("Fred", 1);
    playerMap.put("Bob", 2);
    playerMap.put("Alice", 3);
    playerMap.put("Charlotte", 4);
    playerMap.put("Catherine", 5);
    System.out.println("Players in game: " + playerMap.size());

    /**
     * user input via dialogue to get another playerName String
     * playerName set to Catherine for testing
     */
    String playerName = "Catherine";
    boolean existing = playerMap.containsValue(playerName);
    System.out.println(existing);
    if (existing = true) {
        int playerNumber = 5;
        /**
         * user input via dialogue to get another playerName I need
         * to set playerNumber = highest existing key in map then
         * increment by one then add values to map loop until all
         * players have been entered, I am considering while
         * (playerName != "last"); playerNumber set to 5 for
         * testing
         */
        playerNumber = playerNumber++;
        playerMap.put(playerName, playerNumber);
    }
}

Answer 1

方法containsValue检查地图中是否已存在值。

“凯瑟琳”不是一个价值观。这是关键。

改为使用containsKey。

或者你可能已经反转了键和值。因此，创建一个Map<Integer, String>并在其上放置值。

Answer 2

您可以iterate而不是containsValue，因为containsValue会在内部遍历整个地图。

private boolean exists(String playerName){
   boolean isExists=false;
   for(Map.Entry<String, Integer> playerEntry:playerMap.entry()){
     if(playerEntry.getValue().equals(playerName){
       isExists=true;
       break;
     }
   }
   return isExists;
 }

如果map不包含它将遍历整个地图的值，则为50-50。如果它包含值，它将断开循环并返回true。

然后，您可以使用以下逻辑将put导入playerMap

private void addToMap(String playerName){
 if(playerName!=null && exists(playerName)){
   playerMap.put(playerName, ++playerNumber);
 }
}

Answer 3

您的if语句（existing = true）错误为单个＆＃34; =＆＃34;是分配而不是比较。如果要比较两个布尔值的相等性，则使用double等于＆＃34; ==＆＃34;比较。事实上，你甚至不需要检查现有的＆＃34;变量是真的，因为它已经是一个布尔值，只用if语句包围变量，如果是真，它将进入if块，否则它将赢得。目前，您的代码将始终输入，如果代码阻止，因为您正在分配＆＃34;现有＆＃34;变量为true。

同样如前一张海报所提到的，你使用名称作为键而不是值，所以你应该使用containsKey（）方法而不是containsValue（）。

如果您的地图包含密钥＆＃34; Catherine＆＃34;

，代码下方只应输入if块

  String playerName = "Catherine";
  boolean existing = playerMap.containsKey(playerName);
  if (existing) {
    int playerNumber = 5;
    /**
     * user input via dialogue to get another playerName I need
     * to set playerNumber = highest existing key in map then
     * increment by one then add values to map loop until all
     * players have been entered, I am considering while
     * (playerName != "last"); playerNumber set to 5 for
     * testing
     */
    playerNumber = playerNumber++;
    playerMap.put(playerName, playerNumber);
}

Answer 4

此代码似乎已经完成了这一操作，并列出了所有已输入的玩家名称，感谢所有帮助，只想发布决赛，欢迎任何其他评论！非常享受java ....

 public player()
 {
  Map<Integer, String> playerMap = new HashMap<>();
  int playerNumber = 0;

 do
 {
  String playerName = 'user input request dialogue box' ("Please input a unique player name (5 Maximum): " + ((playerMap.size() - 10) * -1) + " Player slots left.");  
  boolean existing = playerMap.containsValue(playerName);                         
  System.out.println(existing);
  if (existing == false)
  {
    playerNumber = ++playerNumber;
    playerMap.put(playerNumber, playerName);
    System.out.println("Number of players in game: " + playerMap.size());

  }
} 
while (playerNumber < 5);


System.out.println("Players in game are:");
for (int a : playerMap.keySet())
{

  System.out.println("Player " + a + " is \"" + playerMap.get(a) + "\"" );



}

}

将用户输入添加到地图并将整数键递增1

4 个答案: