programming-examples/java/Core_Java/Double Array.java

Double Array

// Double-subscripted array example
import java.awt.*;
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;
         exams = grades[ 0 ].length;
        
         outputArea = new JTextArea();
         Container c = getContentPane();
         c.add( outputArea );
        
         // build the output string
         output = "The array is:\n";
         buildString();
        
         output += "\n\nLowest grade: " + minimum() +
         "\nHighest grade: " + maximum() + "\n";
        
         for ( int i = 0; i < students; i++ )
         output += "\nAverage for student " + i + " is " + average( grades[ i ] );
        
         outputArea.setFont( new Font( "Courier", Font.PLAIN, 12 ) );
         outputArea.setText( output );
     }
    
     // find the minimum grade
     public int minimum()
         {
         int lowGrade = 100;
        
         for ( int i = 0; i < students; i++ )
         for ( int j = 0; j < exams; j++ )
         if ( grades[ i ][ j ] < lowGrade )
         lowGrade = grades[ i ][ j ];
        
         return lowGrade;
     }
    
    
     // find the maximum grade
     public int maximum()
         {
         int highGrade = 0;
        
         for ( int i = 0; i < students; i++ )
         for ( int j = 0; j < exams; j++ )
         if ( grades[ i ][ j ] > highGrade )
         highGrade = grades[ i ][ j ];
        
         return highGrade;
     }
    
     // determine the average grade for a particular
     // student (or set of grades)
     public double average( int setOfGrades[] )
         {
         int total = 0;
        
         for ( int i = 0; i < setOfGrades.length; i++ )
         total += setOfGrades[ i ];
        
         return ( double ) total / setOfGrades.length;
     }
    
     // build output string
     public void buildString()
         {
         output += " "; // used to align column heads
        
         for ( int i = 0; i < exams; i++ )
         output += "[" + i + "] ";
        
         for ( int i = 0; i < students; i++ ) 
             {
             output += "\ngrades[" + i + "] ";
            
             for ( int j = 0; j < exams; j++ )
             output += grades[ i ][ j ] + " ";
         }
     }
}