链表的泛型中异常的NullPointerException

Question

我变得不寻常了，

NullPointerException: Exception in thread "main" java.lang.NullPointerException.

在它自己的TeamClass我有：

  public DSALinkedList<String> players;
  private String name, contactName, ContactAddr, contactEmail, parent;

public Team(String inName, String inConName, String inConAddr, String inConEmail, String inParent)
{     


        name = inName;
        DSALinkedList<String> players = new DSALinkedList<String>(); //Constructs an empty players list using Strings as the value.
        parent = inParent;
        contactName = inConName;
        ContactAddr = inConAddr;
        contactEmail = inConEmail;

}

//用方法

public void addPlayer(String inPlayer)
{
    players.insertFirst(inPlayer);        
}

然后在我的Main类中，我从文件构建一个团队，该团队调用此方法：

public static Team constructTeam(String inLine)
    {
   String[] lineArray = new String[16];
   lineArray = inLine.split(",");  

    int i;
    String name, contact, email, address, parent;
    name = lineArray[1];
    parent = lineArray[2];
    contact = lineArray[3];
    email = lineArray[4];
    address = lineArray[5];

    Team team = new Team(name, contact, address, email, parent);
    System.out.println(team.getName());

//这是一项健全性检查，可以正确打印团队名称，这对我来说表明'team'不为空。
//将玩家（字符串）添加到玩家列表。 “玩家：名字姓”

    for(i=6; i<15; i++) //First player in lineArray to potentially the last.
    {
        if(!lineArray[i].equals("")) 
        {
            System.out.println("Test:"+ lineArray[i]);
            String player = lineArray[i];
            team.addPlayer(player); //ERROR OCCURS HERE
        }
    }

  return team;
}

Answer 1

要重新声明你的类变量- DSALinkedList<String> players在这条线的构造， DSALinkedList<String> players = new DSALinkedList<String>(); ，

应该只是- players = new DSALinkedList<String>();

因此，在此下面的方法中， players由于其类变量而为NULL。

public void addPlayer(String inPlayer) {
    players.insertFirst(inPlayer);        
}

Answer 2

播放器将通过以下方式使用：

public DSALinkedList<String> players;
  private String name, contactName, ContactAddr, contactEmail, parent;

public Team(String inName, String inConName, String inConAddr, String inConEmail, String inParent)
{     


        name = inName;
        players = new DSALinkedList<String>(); //Constructs an empty players list using Strings as the value.
        parent = inParent;
        contactName = inConName;
        ContactAddr = inConAddr;
        contactEmail = inConEmail;

}