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我目前的代码有问题。我必须将小时和分钟声明为 int，将 totalTimeHours 声明为 double。totalTimeHours 用于以小时为单位存储总时间，例如 6.555 小时。例如，我正在处理的问题需要在几小时和几分钟内找到答案。6小时36分钟。对于我的最后一次跑步，我需要使用 14.7 加仑的汽油和 359.5 的距离。我使用 hours = (int)totalTimeHours 来提取整数 6，并且应该找到剩余的时间并将其乘以 60 以找到分钟，但这就是我被耽搁的地方。

下面是我的代码：

  public static void computeMilesPerGallon()
  {   //start brackett for computeMilesPerGallon

     double gallons, distance, mpg, totalTimeHours;   //totalTimeHours is the total  time in just hours
                                                                         //for example totalTimeHours = 6.5555 hrs
     int minutes, hours;
     final String DASHES = "-----------------------------------------------";
     final double AVERAGE_SPEED = 54.5;     

     DecimalFormat oneDecimalDigits = new DecimalFormat ("0.0");   //prints decimal to 1 places
     DecimalFormat threeDecimalDigits = new DecimalFormat ("0.000");   //prints decimal to 3 places  

     System.out.println ("\n\t\t\tSpeed Problem");
     System.out.println ("\t\t\t-------------");
     System.out.print ("\n\t\tEnter in the gallons of gas used: ");   //gets gallons of gas used
     gallons = scan.nextDouble();

     System.out.print ("\t\tEnter in the total distance driven: ");   //gets total distance driven
     distance = scan.nextDouble();

     mpg = distance / gallons;   //calculates mpg
     System.out.println ("\t\tThis is your miles per gallon (mpg): " + oneDecimalDigits.format(mpg));  
                                                                         //displays mpg
    //calculates time// 
     totalTimeHours = distance / AVERAGE_SPEED;

    //below line displays total time in hours to 3 decimal places
     System.out.println ("\n\t\tThis is was your time in hours: " 
                                        + threeDecimalDigits.format(totalTimeHours));

    //extracts hours from time in hours
     hours = (int)totalTimeHours;
        minutes = Math.round((totalTimeHours - hours) * 60);

    //prints total time in hrs and minutes
     System.out.println ("\t\tThis is the total time in hours and minutes: " + hours 
                                            + " hours and " + minutes + " minutes");  

     System.out.println ("\t" + DASHES);

  }
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2 回答 2

5

替换：

minutes = Math.round((totalTimeHours - hours) * 60);

与：

minutes = Math.round((float)((totalTimeHours - hours) * 60));

或者

minutes = (int)Math.round((totalTimeHours - hours) * 60);

数学中有两种方法

long Math.round(double);
int Math.round(float);

您正在传递一个双参数，因此您调用返回 long 的参数并将其分配给 int ，这是错误的。

于 2013-06-06T16:47:05.430 回答
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我没有阅读您的所有代码，但这应该有助于解决您在文本中描述的问题：

    double dTime = 6.555;
    int hours = (int) dTime;
    int minutes = (int) ((dTime - hours) * 60);
    System.out.println(hours + ":" + minutes); // prints 6:33
于 2013-06-06T16:44:53.650 回答