examgrades.java

java源程序 对初学者有很大的帮助 从简单到复杂

//********************************************************************
//  ExamGrades.java       Author: Lewis/Loftus
//
//  Demonstrates the use of various control structures.
//********************************************************************

import java.text.DecimalFormat;
import cs1.Keyboard;

public class ExamGrades
{
   //-----------------------------------------------------------------
   //  Computes the average, minimum, and maximum of a set of exam
   //  scores entered by the user.
   //-----------------------------------------------------------------
   public static void main (String[] args)
   {
      int grade, count = 0, sum = 0, max, min;
      double average;

      //  Get the first grade and give max and min that initial value
      System.out.print ("Enter the first grade (-1 to quit): ");
      grade = Keyboard.readInt();

      max = min = grade;

      //  Read and process the rest of the grades
      while (grade >= 0)
      {
         count++;
         sum += grade;

         if (grade > max)
            max = grade;
         else
            if (grade < min)
               min = grade;

         System.out.print ("Enter the next grade (-1 to quit): ");
         grade = Keyboard.readInt ();
      }

      //  Produce the final results
      if (count == 0)
         System.out.println ("No valid grades were entered.");
      else
      {
         DecimalFormat fmt = new DecimalFormat ("0.##");
         average = (double)sum / count;
         System.out.println();
         System.out.println ("Total number of students: " + count);
         System.out.println ("Average grade: " + fmt.format(average));
         System.out.println ("Highest grade: " + max);
         System.out.println ("Lowest grade: " + min);
      }
   }
}