Question

HY，

我遇到一本书中的一个代码问题首先是Java ... （第63/64页）

我重新编写了代码但它没有用。有人可以解释一下那是什么吗？

我在Eclipse中遇到的错误是：

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
The public type GuessGame must be defined in its own file
The public type Player must be defined in its own file

at GuessGame.<init>(GameLauncher.java:1)
at GameLauncher.main(GameLauncher.java:73)

并且代码为：

public class GuessGame {
    Player p1;
    Player p2;
    Player p3;

    public void startGame(){
        p1 = new Player();
        p2 = new Player();
        p3 = new Player();

        int guessp1 = 0;
        int guessp2 = 0;
        int guessp3 = 0;

        boolean p1isright = false;
        boolean p2isright = false;
        boolean p3isright = false;

        int BrojKojiTrebaPogodit = (int)(Math.random() * 10);
        System.out.println ("Razmisljam o broju izmedju 0 i 9 ... ");

        while (true){
            System.out.println ("Zamisljeni broj je " + BrojKojiTrebaPogodit);
            p1.guess();
            p2.guess();
            p3.guess();

            guessp1 = p1.number;
            System.out.println ("Player P1 guessed " + guessp1);
            guessp2 = p2.number;
            System.out.println ("Player P2 guessed " + guessp2);
            guessp3 = p3.number;
            System.out.println ("Player P3 guessed " + guessp3);

            if (guessp1 == BrojKojiTrebaPogodit){
                p1isright = true;
            }
            if (guessp2 == BrojKojiTrebaPogodit){
                p2isright = true;
            }
            if (guessp3 == BrojKojiTrebaPogodit){
                p3isright = true;
            }

            if (p1isright || p2isright || p3isright) {
                System.out.println ("We have winner!");
                System.out.println ("Is P1 got it right? " + p1isright);
                System.out.println ("Is P2 got it right? " + p2isright);
                System.out.println ("Is P3 got it right? " + p3isright);
                System.out.println ("Game is over");
                break;
            }
            else {
                System.out.println ("Players will have to try again!");
            }
        }
    }
}

public class Player {
    int number = 0;

    public void guess() {
        number = (int) (Math.random()*10);
        System.out.println("I'm guessing " + number);
    }
}

public class GameLauncher {
    public static void main (String[] imeStringa){
        GuessGame game = new GuessGame();
        game.startGame();
    }
}

THX

Answer 1

您只能在.java文件中声明一个公共类

Answer 2

每个java文件只能有一个公共类

Answer 3

在Java中，文件中只能有一个公共类。如果你想拥有多个公共类，那就选择内部类。有an example here。

为什么单个文件不能有多个公共类。当我开始使用java时，我心里也有同样的问题。无论我问谁，我都得到了相同的答案 - “这就是它的工作方式”。

此致约翰

Answer 4

错误消息告诉您错误：您的代码无法编译（您应该在Eclipse的“Problems”视图中看到红色错误标记），因为Java中的每个公共类都应该在一个单独的文件中定义班级名称：

public class GuessGame --> must be in GuessGame.java

public class Player --> must be in Player.java

package com.foo.bar;
public class GuessGame  --> must be in com/foo/bar/GuessGame.java

注意：Eclipse允许你启动一个应用程序，即使它没有编译，但你不应该：它不会工作。

Answer 5

你需要将Player和GameLauncher类放在他们自己的类文件中，或者通过在GameLauncher类下面的玩家类之前移动括号}来使它们成为内部类。游戏启动器类必须是静态的，并且在GameLauncher类之后还有一个额外的括号}

Answer 6

正如上面提到的很多人，你不能拥有一个以上的公共课......所以只要把它放在除了GuessGame之外的类不公开的地方。除此之外，我刚刚接受了最后一个类，并将其作为GuessGame的主要部分，因为它是公共类，使得startGame静态并使Player类也是静态的。然后我打电话给startGame（）;在主要。

public class GuessGame {
static Player p1;
static Player p2;
static Player p3;

public static void main(String[] args) {
  startGame();
}
public static void startGame(){
    p1 = new Player();
    p2 = new Player();
    p3 = new Player();

    int guessp1 = 0;
    int guessp2 = 0;
    int guessp3 = 0;

    boolean p1isright = false;
    boolean p2isright = false;
    boolean p3isright = false;

    int BrojKojiTrebaPogodit = (int)(Math.random() * 10);
    System.out.println ("Razmisljam o broju izmedju 0 i 9 ... ");

    while (true){
        System.out.println ("Zamisljeni broj je " + BrojKojiTrebaPogodit);
        p1.guess();
        p2.guess();
        p3.guess();

        guessp1 = p1.number;
        System.out.println ("Player P1 guessed " + guessp1);
        guessp2 = p2.number;
        System.out.println ("Player P2 guessed " + guessp2);
        guessp3 = p3.number;
        System.out.println ("Player P3 guessed " + guessp3);

        if (guessp1 == BrojKojiTrebaPogodit){
          p1isright = true;
        }
        if (guessp2 == BrojKojiTrebaPogodit){
          p2isright = true;
        }
        if (guessp3 == BrojKojiTrebaPogodit){
          p3isright = true;
        }
        if (p1isright || p2isright || p3isright) {
          System.out.println ("We have winner!");
          System.out.println ("Is P1 got it right? " + p1isright);
          System.out.println ("Is P2 got it right? " + p2isright);
          System.out.println ("Is P3 got it right? " + p3isright);
          System.out.println ("Game is over");
          break;
        }
        else {
          System.out.println ("Players will have to try again!");
        }
      }
    }
  }

  class Player {
  int number = 0;

  public void guess() {
    number = (int) (Math.random()*10);
    System.out.println("I'm guessing " + number);
  }
}

Answer 7

每个.java文件一个公共类。

有关参考，请参阅第7页上的 Head First Java 一书。（潜入 A Quick Dip ）

Java猜猜游戏

7 个答案: