将int转换为double Java

Question

我目前遇到了代码问题.我必须将小时和分钟声明为int,将totalTimeHours声明为double.totalTimeHours用于存储总时间,以小时为单位,前6.555小时.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.对于我的最后一次运行,我需要使用14.7加仑气体和359.5距离.我使用hours =(int)totalTimeHours来提取整数6,我应该找到剩下的剩余时间并将其乘以60以找到分钟,但这就是我被阻止的地方.

以下是我的代码:

  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);

  }

Answer 1

替换:

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

用:

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

要么

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

数学中有两种方法

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

你正在传递一个双参数,所以你调用一个返回long的那个并将它分配给一个int,这是错误的.