java - 使用派生类创建对象数组

Question

我正在尝试在我正在编写的程序中创建两个玩家。问题是可以创建三种类型的玩家，但为了稍后引用它们，我希望将它们命名为玩家一和玩家二。三个类:“Human”、“Computer”和“Karen”是“Player”的派生类。我想知道如何创建一个数组 Player，然后我可以将player1 和player2 对象放入其中。这可以做到吗？

int playerType = 0;
int highestScore = 0;
Player[] player = new Player[2]; // This is the array of type Player, the master class

Scanner userInput = new Scanner (System.in);

for (int i = 1; i < 3; i++)
{
    System.out.println ("Choose a type of player:");
    System.out.println ("1: Human");
    System.out.println ("2: Computer (Threshold = 20)");
    System.out.println ("3. Computer (Custom)");
    System.out.print ("? : ");

    playerType = Integer.valueOf(userInput.nextLine()); // gets input choice from user


  switch (playerType)
    {
      case 1:
        Human player[i] = new Human();
      case 2:
        Computer player[i] = new Computer();
      case 3:
        Karen player[i] = new Karen();
    }

}

我尝试了另一种方法，使用 if 语句根据我们所处的 for 循环的迭代来创建对象playerOne 或playerTwo (i)。不幸的是，java 似乎不会编译它，因为同一个变量有多个声明，即使只有其中一个声明应该运行。

if(playerNumber == 1){
  switch (playerType)
    {
      case 1:
        Human playerOne = new Human();
      case 2:
        Computer playerOne = new Computer();
      case 3:
        Karen playerOne = new Karen();
    }
}

if(playerNumber == 2){
  switch (playerType)
    {
      case 1:
        Human playerTwo = new Human();
      case 2:
        Computer playerTwo = new Computer();
      case 3:
        Karen playerTwo = new Karen();
    }
}

OldProgrammer建议的解决方案如下，效果很好。但是，我现在在调用以下方法时遇到问题:人类、计算机和凯伦。尝试执行时出现以下错误:

System.out.println(player[i].getName() + ", your turn");

错误消息:

Main.java:38: error: cannot find symbol
    System.out.println(player[i].getName() + ", your turn");
                                ^
symbol:   method getName()
location: class Player
1 error

每个类中的方法如下所示:

public class Karen extends Player {
private String playerName = "Karen";

public String getName(){
  return playerName;
}

}

Answer 1

感谢老程序员:

Change "Human player[i] = new Human();" to "player[i] = new Human();", etc.

了解派生类的工作原理非常重要，我很高兴这就是它的工作原理。非常感谢你，我希望这可以帮助将来的人。这是我更新的代码以进行全面说明:

int highestScore = 0;
Player[] player = new Player[2]; 

Scanner userInput = new Scanner (System.in);

for (int i = 0; i < 2; i++)
{
    System.out.println ("Choose a type of player:");
    System.out.println ("1: Human");
    System.out.println ("2: Computer (Threshold = 20)");
    System.out.println ("3. Computer (Custom)");
    System.out.print ("? : ");

    playerType = Integer.valueOf(userInput.nextLine());

  switch (playerType)
    {
      case 1:
        player[i] = new Human();
      case 2:
        player[i] = new Computer();
      case 3:
        player[i] = new Karen();
    }

}