gradebook.java

成绩管理系统可以对学生、课程、选课、成绩的录入、班级、用户的信息进行管理等

package coursedesign;

public class GradeBook
{
   private String courseName;
   private int grades[][]; // two-dimensional array of student grades


   public GradeBook( String name, int gradesArray[][] )
   {
      courseName = name; // initialize courseName
      grades = gradesArray; // store grades
   } // end two-argument GradeBook constructor

   // method to set the course name
   public void setCourseName( String name )
   {
      courseName = name;
   }


   public String getCourseName()
   {
      return courseName;
   } // end method getCourseName

   // display a welcome message to the GradeBook user
   public void displayMessage()
   {
      // getCourseName gets the name of the course
      System.out.printf( "Welcome to the grade book for\n%s!\n\n",
         getCourseName() );
   } // end method displayMessage

   // perform various operations on the data
   public void processGrades()
   {
      // output grades array
      outputGrades();
     // output grade distribution chart of all grades on all tests
      outputBarChart();
   } // end method processGrades

   // determine average grade for particular student (or set of grades)
   public double getAverage( int setOfGrades[] )
   {
      int total = 0; // initialize total

      // sum grades for one student
      for ( int grade : setOfGrades )
         total += grade;

      // return average of grades
      return (double) total / setOfGrades.length;
   } // end method getAverage

   // output bar chart displaying overall grade distribution
   public void outputBarChart()
   {
      System.out.println( "Overall grade distribution:" );

      // stores frequency of grades in each range of 10 grades
      int frequency[] = new int[ 11 ];

      // for each grade in GradeBook, increment the appropriate frequency
      for ( int studentGrades[] : grades )
      {
         for ( int grade : studentGrades )
            ++frequency[ grade / 10 ];
      } // end outer for

      // for each grade frequency, print bar in chart
      for ( int count = 0; count < frequency.length; count++ )
      {
         // output bar label ( "00-09: ", ..., "90-99: ", "100: " )
         if ( count == 10 )
            System.out.printf( "%5d: ", 100 );
         else
            System.out.printf( "%02d-%02d: ",
               count * 10, count * 10 + 9  );

         // print bar of asterisks
         for ( int stars = 0; stars < frequency[ count ]; stars++ )
            System.out.print( "*" );

         System.out.println(); // start a new line of output
      } // end outer for
   } // end method outputBarChart

   // output the contents of the grades array
   public void outputGrades()
   {
      System.out.println( "The grades are:\n" );
      System.out.print( "            " ); // align column heads

      // create a column heading for each of the tests
      for ( int test = 0; test < grades[ 0 ].length; test++ )
         System.out.printf( "Test %d  ", test + 1 );

      System.out.println( "Average" ); // student average column heading

      // create rows/columns of text representing array grades
      for ( int student = 0; student < grades.length; student++ )
      {
         System.out.printf( "Student %2d", student + 1 );

         for ( int test : grades[ student ] ) // output student's grades
            System.out.printf( "%8d", test );

         // call method getAverage to calculate student's average grade;
         // pass row of grades as the argument to getAverage
         double average = getAverage( grades[ student ] );
         System.out.printf( "%9.2f\n", average );
      } // end outer for
   } // end method outputGrades
} // end class GradeBook