Question

我有一个包含Objects的ArrayList。我一直想要/需要做的是在ArrayList中搜索一个特定的对象，如果找到则改变其中一个值。 I.E.我有一队足球运动员，说费城老鹰队包含球队名称，得分总计得分，然后按名字，姓氏，比赛和位置列出所有球员。我正在寻找一个特定的球员，说Chad Hall，我想把他从老鹰队中移除并将他交易给新英格兰爱国者队。到目前为止我所拥有的是ArrayList的迭代，但是我的代码没有找到播放器然后退出。

case 6:
           String name = "";
           System.out.print("Who would you like to trade? ");
           name = kb.nextLine();
           tradePlayer(nflTeams, name);

public static void tradePlayer(ArrayList<Team> nflTeams, String name)
  {
     Scanner kb = new Scanner(System.in);
     String teamName = "";
     System.out.print("What team do you want to trade this player to?(Team Acronym) "    );
     teamName = kb.nextLine();

     for(Team t: nflTeams){
        if (nflTeams.contains(name.toLowerCase()))
                      t.setName(teamName);
                }
     System.out.println("Cannot find " + name);
  }

Player课程通过名字，姓氏，队伍，位置和比赛来构建球员。我想改变的是团队。在Team课程中，我有setName(String)来设置团队名称。

非常感谢任何建议或想法。

Answer 1

if (nflTeams.contains(name.toLowerCase()))

你想做什么？您的列表nflTeams包含Team个对象而非名称这不起作用。
如果您需要通过其Team访问name，请改用Map<String,Team>

Answer 2

您必须从指定的name获取团队中的玩家列表并从中删除，如：

String teamToAddNewPlayer = "New England Patriots";
String deletedPlayer = null;
for(Team t: nflTeams){
      List<String> players = t.getPlayers();
      if (players.contains(name)){
          deletedPlayer = players.remove(name);
      }
      if (t.getName().equals(teamToAddNewPlayer))
          players.add(name);
}
if (deletedPlayer == null)
//nothing was deleted
else
//player was deleted

Answer 3

使用迭代器可以让您更好地控制您正在尝试的内容。

import java.util.*;

 class IteratorDemo {


public static void main(String args[]) {
      // Create an array list
      ArrayList al = new ArrayList();
      // add elements to the array list
      al.add("C");
      al.add("A");
      al.add("E");
      al.add("B");
      al.add("D");
      al.add("F");

  // Use iterator to display contents of al
  System.out.print("Original contents of al: ");
  Iterator itr = al.iterator();
  while(itr.hasNext()) {
     Object element = itr.next();
     System.out.print(element + " ");
  }
  System.out.println();

  // Modify objects being iterated
  ListIterator litr = al.listIterator();
  while(litr.hasNext()) {
     Object element = litr.next();
     litr.set(element + "+");
  }
  System.out.print("Modified contents of al: ");
  itr = al.iterator();
  while(itr.hasNext()) {
     Object element = itr.next();
     System.out.print(element + " ");
  }
  System.out.println();

  // Now, display the list backwards
  System.out.print("Modified list backwards: ");
  while(litr.hasPrevious()) {
     Object element = litr.previous();
     System.out.print(element + " ");
   }
   System.out.println();
}
}

此示例来自source

搜索和更改arraylist中的Object

3 个答案: