// Fig. 7.16: DoubleArray.java
// Double-subscripted array example

// Java core packages
import java.awt.*;

// Java extension packages
import javax.swing.*;

public class DoubleArray extends JApplet {
   int grades[][] = { { 77, 68, 86, 73 }, 
                      { 96, 87, 89, 81 },
                      { 70, 90, 86, 81 } };

   int students, exams;
   String output;
   JTextArea outputArea;

   // initialize instance variables
   public void init()
   {
      students = grades.length;     // number of students
      exams = grades[ 0 ].length;   // number of exams

      // create JTextArea and attach to applet
      outputArea = new JTextArea();
      Container container = getContentPane();
      container.add( outputArea );

      // build output string
      output = "The array is:\n";
      buildString();

      // call methods minimum and maximum
      output += "\n\nLowest grade: " + minimum() +
                "\nHighest grade: " + maximum() + "\n";

      // call method average to calculate each student's average
      for ( int counter = 0; counter < students; counter++ ) 
         output += "\nAverage for student " + counter + " is " +
            average( grades[ counter ] );

      // change outputArea's display font
      outputArea.setFont(
         new Font( "Courier", Font.PLAIN, 12 ) );

      // place output string in outputArea
      outputArea.setText( output );
   }

   // find minimum grade
   public int minimum()
   { 
      // assume first element of grages array is smallest
      int lowGrade = grades[ 0 ][ 0 ];

      // loop through rows of grades array
      for ( int row = 0; row < students; row++ ) 

         // loop through columns of current row
         for ( int column = 0; column < exams; column++ ) 

            // Test if current grade is less than lowGrade.
            // If so, assign current grade to lowGrade.
            if ( grades[ row ][ column ] < lowGrade )
               lowGrade = grades[ row ][ column ];

      return lowGrade;  // return lowest grade
   }

   // find maximum grade
   public int maximum()
   { 
      // assume first element of grages array is largest
      int highGrade = grades[ 0 ][ 0 ];

      // loop through rows of grades array
      for ( int row = 0; row < students; row++ ) 

         // loop through columns of current row
         for ( int column = 0; column < exams; column++ ) 

            // Test if current grade is greater than highGrade.
            // If so, assign current grade to highGrade.
            if ( grades[ row ][ column ] > highGrade )
               highGrade = grades[ row ][ column ];

      return highGrade;  // return highest grade
   }

   // determine average grade for particular
   // student (or set of grades)
   public double average( int setOfGrades[] )
   {
      int total = 0;  // initialize total
 
      // sum grades for one student
      for ( int count = 0; count < setOfGrades.length; count++ )
         total += setOfGrades[ count ];

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

   // build output string
   public void buildString()
   {
      output += "           ";  // used to align column heads

      // create column heads
      for ( int counter = 0; counter < exams; counter++ ) 
         output += "[" + counter + "]  ";

      // create rows/columns of text representing array grades
      for ( int row = 0; row < students; row++ ) {
         output += "\ngrades[" + row + "]   ";

         for ( int column = 0; column < exams; column++ ) 
            output += grades[ row ][ column ] + "   ";
      }
   }
}

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 * (C) Copyright 2002 by Deitel & Associates, Inc. and Prentice Hall.     *
 * All Rights Reserved.                                                   *
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