gradebook.java

I holp somebody will need it.

// Fig. 7.14: GradeBook.java
// Grade book using an array to store test grades.

public class GradeBook
{
   private String courseName; // name of course this GradeBook represents
   private int grades[]; // array of student grades
   
   // two-argument constructor initializes courseName and grades array
   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; // store the course name
   } // end method setCourseName

   // method to retrieve the course 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();

      // call method getAverage to calculate the average grade      
      System.out.printf( "\nClass average is %.2f\n", getAverage() ); 

      // call methods getMinimum and getMaximum
      System.out.printf( "Lowest grade is %d\nHighest grade is %d\n\n",
         getMinimum(), getMaximum() );

      // call outputBarChart to print grade distribution chart
      outputBarChart();
   } // end method processGrades

   // find minimum grade
   public int getMinimum()
   { 
      int lowGrade = grades[ 0 ]; // assume grades[ 0 ] is smallest

      // loop through grades array
      for ( int grade : grades ) 
      {
         // if grade lower than lowGrade, assign it to lowGrade
         if ( grade < lowGrade )
            lowGrade = grade; // new lowest grade
      } // end for

      return lowGrade; // return lowest grade
   } // end method getMinimum

   // find maximum grade
   public int getMaximum()
   { 
      int highGrade = grades[ 0 ]; // assume grades[ 0 ] is largest

      // loop through grades array
      for ( int grade : grades ) 
      {
         // if grade greater than highGrade, assign it to highGrade
         if ( grade > highGrade )
            highGrade = grade; // new highest grade
      } // end for

      return highGrade; // return highest grade
   } // end method getMaximum

   // determine average grade for test
   public double getAverage()
   {      
      int total = 0; // initialize total
 
      // sum grades for one student
      for ( int grade : grades )
         total += grade;

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

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

      // stores frequency of grades in each range of 10 grades
      int frequency[] = new int[ 11 ];
      
      // for each grade, increment the appropriate frequency 
      for ( int grade : grades )
         ++frequency[ grade / 10 ];

      // 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" );
      
      // output each student's grade
      for ( int student = 0; student < grades.length; student++ ) 
         System.out.printf( "Student %2d: %3d\n", 
            student + 1, grades[ student ] );
   } // end method outputGrades
} // end class GradeBook


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