使用具有多态性的反射来实例化 class 的最佳方法是什么？

Question

I'm trying to use Reflection in java to
instantiate a Player with a Command Pattern likes below :

一条命令中只有一个'execute'方法class,
而InitiatePlayerCommand作为它的名字，它会实例化一个
subclass of Player 根据构造函数中传入的playerClass

I have two kind of subclass of Player class : HumanPlayer and AiPlayer for polymorphism.

我希望它会实例化其中一个 subclass 并添加到 playerList

但我不知道用反射达到这个目的的最佳方法是什么。它总是发生类型转换错误。

public class InitiatePlayerCommand implements Command{
private List<Player> playerList;
private String name;
private WarMode warMode;
private Class<?> playerClass;
public <T extends Player> InitiatePlayerCommand(String name, WarMode mode ,List<Player> list
        ,Class<T> playerClass){
    this.name = name;
    this.warMode = mode;
    this.playerList = list;
    this.playerClass = playerClass;
}

@Override
public void execute() throws InstantiationException, IllegalAccessException, IllegalArgumentException, NoSuchFieldException, SecurityException {
    Player player = (Player) playerClass.newInstance();
    player.setName(name);
    player.setWarMode(warMode);
    playerList.add(player);
}

public static void main(String[] argv){
    List<Player> playerList = new ArrayList<Player>();
    new InitiatePlayerCommand("Johnny",WarMode.MILITARY,playerList,HumanPlayer.class)
            .execute();  // this line get an error HumanPlayer.class isn't compatible to Class<T extends Player> playerClass
    System.out.println(playerList);

}

}

有什么方法可以不使用 Class

达到这个

Answer 1

您应该考虑使用 Supplier<T>，这是一个 returns 对象的无参数函数。

在这种情况下，您的 Supplier 可能定义如下：

Supplier<Player> playerSupplier = () -> new HumanPlayer();

然后您可以像这样使用它：

public void execute() {
    Player player = playerSupplier.get();
    player.setName(name);
    player.setWarMode(warMode);
    playerList.add(player);
}

使用具有多态性的反射来实例化 class 的最佳方法是什么？

What is the best way to instantiate a class using Reflection with the polymorphism?

java

reflection

polymorphism

class

command-pattern