我的Rolling Craps代码有什么问题？

-2

所以我编写了一个掷骰子游戏，它要求我掷两个骰子并返回骰子的总和。滚动7或11会赢得比赛，滚动2,3或12会让你失去比赛。滚动4,5,6,8,9,10将“确定点”，用户继续滚动，直到他们滚动已建立的相同数字或直到他们掷出7，在这种情况下他们输了。我的Rolling Craps代码有什么问题？

以我为例，我得到，说

"Exception in thread "main" java.lang.NullPointerException 
at Craps.getSum(Craps.java:24) 
at Craps.playRound(Craps.java:29) 
at Craps.main(Craps.java:70) 
C:\Users\owner\AppData\Local\NetBeans\Cache\8.2\executor-snippets\run.xml:53: Java returned: 1 
BUILD FAILED (total time: 2 seconds)"

我模具类看起来像这样的例外：

import java.util.Random; 
public class Die 
{ 
    private int number; 
    private Random generator; 

    public Die() 
    { 
     generator = new Random(); 
     roll(); 
    } 

    public int getNumber() 
    { 
     return number; 
    } 

    public void roll() 
    { 
     number = generator.nextInt(6)+1; 
    } 
}

而且我掷骰子的游戏看起来是这样的：

import java.util.Scanner; 

public class Craps 
{ 
    private Die die1; 
    private Die die2; 

    private void rollDice() 
    { 
     die1.roll(); 
     die2.roll(); 
    } 

    private int getSum() 
    { 
     return (die1.getNumber() + die2.getNumber()); 
    } 

    public void playRound() 
    { 
     if (getSum() == 7 || getSum() == 11) 
     { 
      System.out.println("You rolled a " +getSum()+ "! You win!!!"); 
     } 
     else if(getSum() == 2 || getSum() == 3 || getSum() == 12) 
     { 
      System.out.println("You rolled a " +getSum()+ " You lose."); 
     } 
     else if(getSum() == 4 || getSum() == 5 || getSum() == 6 || getSum() == 8 || getSum() == 9 || getSum() == 10) 
     { 
      int established = getSum(); 
      System.out.println("Establishing the point... Re-Rolling..."); 
      rollDice(); 

      do 
      { 
       rollDice(); 
       System.out.println("You rolled a " +getSum()); 
      } 
      while (getSum() != established && getSum() != 7); 

      if (getSum() == established) 
      { 
       System.out.println("You rolled a " +getSum()+ " which is also the established point, You win!"); 
      } 
      else if(getSum() == 7) 
      { 
       System.out.println("You rolled a 7 after establishing the point, you lose."); 
      } 

     }  
    } 

    public static void main(String[] args) 
    { 
     Craps game = new Craps(); 
     Scanner scan = new Scanner(System.in); 
     System.out.println("Welcome to the game of Craps!"); 
     System.out.println("Would you like to play a game? (Y/N"); 
     String input = scan.nextLine(); 
     if (input.equalsIgnoreCase("Y")) 
     { 
      game.playRound(); 
     } 
     else 
     { 
      System.out.println("Okay see you next time!"); 
      System.exit(1); 
     } 
    } 
}

来源

2017-04-07 iHaunt

你不会得到一个“空错误” - 你会得到一个异常，告诉你到底发生了什么问题和错误。你应该在问题中包含它。 – John3136

@ John3136编辑，谢谢指出。 – iHaunt

[什么是空指针异常，以及如何解决它？]可能重复（http://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-doi-i-fix -它）？提示：“新Die（）”在哪里？ – IQV

-4

private Die die1; 
private Die die2;

保留空引用。

来源

2017-04-07 06:11:18

我可否知道投票的原因？ –

我的Rolling Craps代码有什么问题？

回答

相关问题