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 语句根据我们所在的 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，效果非常好。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：更改“人类玩家[i] = new Human();”&nbsp;到“player[i] = new Human();”等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];&nbsp;Scanner userInput = new Scanner (System.in);for (int i = 0; i < 2; i++){&nbsp; &nbsp; System.out.println ("Choose a type of player:");&nbsp; &nbsp; System.out.println ("1: Human");&nbsp; &nbsp; System.out.println ("2: Computer (Threshold = 20)");&nbsp; &nbsp; System.out.println ("3. Computer (Custom)");&nbsp; &nbsp; System.out.print ("? : ");&nbsp; &nbsp; playerType = Integer.valueOf(userInput.nextLine());&nbsp; switch (playerType)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; case 1:&nbsp; &nbsp; &nbsp; &nbsp; player[i] = new Human();&nbsp; &nbsp; &nbsp; case 2:&nbsp; &nbsp; &nbsp; &nbsp; player[i] = new Computer();&nbsp; &nbsp; &nbsp; case 3:&nbsp; &nbsp; &nbsp; &nbsp; player[i] = new Karen();&nbsp; &nbsp; }}