Java for循环创建n个对象
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Java for loop to create n amount of object
提问by Sizemj
I need some help. I want to create a for loop that creates n number of objects of a class, and then adds them into an arraylist. Something like this:
我需要一些帮助。我想创建一个 for 循环来创建一个类的 n 个对象，然后将它们添加到一个数组列表中。像这样的东西：
//Player is a custom class
ArrayList<Player> numberofPlayersArray;
numberofPlayersArray = new ArrayList<Player>();
//n is a variable for the number of Player class objects that I want to create
for(int i = 0; i < n; i++)
{
//this is what I can come up with but I am missing something
Player p;
p = new Player
numberofPlayersArray.add(p);
}
Any help would be appreciated
任何帮助，将不胜感激
回答by Asaph
Your code looks syntactically correct with one exception.
除了一个例外，您的代码在语法上看起来是正确的。
Change
改变
p = new Player
to
到
p = new Player();
I'm assuming the variable nis declared and initialized and the Playerclass is defined with an argless constructor.
我假设变量n已声明并初始化，并且Player类是使用无参数构造函数定义的。
回答by Bozho
//Player is a custom class
ArrayList<Player> numberofPlayersArray = new ArrayList<Player>(n);
//n is a variable for the number of Player class objects that I want to create
for(int i = 0; i < n; i++) {
//this is what I can come up with but I am missing something
Player p = new Player();
numberofPlayersArray.add(p);
}
Note that it's better to initialize the ArrayListwith the size, if it is known (as in your case)
请注意，最好ArrayList用大小初始化（如果已知）（如您的情况）
回答by Fortyrunner
Don't forget to code to the interface (rather than the concrete class).
不要忘记对接口（而不是具体类）进行编码。
List<Player> numberofPlayers = new ArrayList<Player>(n);
Forgetting to do this (or not knowing about it) is a common beginners mistake.
忘记这样做（或不知道）是初学者常见的错误。
If you decide to switch to an alternative list implementation later on (LinkedList or maybe a Google Collection or an Apache Commons Collection list) you won't have to change every reference to the list - just the initial allocation.
如果您决定稍后切换到替代列表实现（LinkedList 或 Google 集合或 Apache Commons 集合列表），您将不必更改对列表的每个引用 - 只需更改初始分配。
回答by Andreas Dolk
I don't see a problem here, just do
我在这里没有看到问题，只是做
p = new Player();
(but this might just have been a typo) and the playerlist will be populated with n different Player objects.
（但这可能只是一个错字）并且玩家列表将填充 n 个不同的 Player 对象。
Note, that I'm just assuming, you want to use the default constructor for Player.
请注意，我只是假设您想使用 Player 的默认构造函数。
Naming hint: you shouldn't name a List '..Array', unless you want to confuse yourself ;) Just name it '..List'
命名提示：您不应该将 List 命名为“..Array”，除非您想混淆自己；) 只需将其命名为“..List”
