Student Poll Calculation

StudentPoll.java

// Fig. 7.8: StudentPoll.java
// Poll analysis program.
public class StudentPoll {
  public static void main( String[] args ) {
  // student response array (more typically, input at runtime)
  int[] responses = { 1, 2, 5, 4, 3, 5, 2, 1, 3, 3, 1, 4, 3, 3, 3, 2, 3, 3, 2, 14 };
  int[] frequency = new int[ 6 ]; // array of frequency counters

  // for each answer, select responses element and use that value
  // as frequency index to determine element to increment
  for ( int answer = 0; answer < responses.length; answer++ ) {
    try {
      ++frequency[ responses[ answer ] ];
    } // end try
    catch ( ArrayIndexOutOfBoundsException e ) {
      System.out.println( e );
      System.out.printf( "   responses[%d] = %d\n\n", answer, responses[ answer ] );
    } // end catch
  } // end for
  
  System.out.printf( "%s%10s\n", "Rating", "Frequency" );

  // output each array element's value
  for ( int rating = 1; rating < frequency.length; rating++ )
    System.out.printf( "%6d%10d\n", rating, frequency[ rating ] );
  } // end main
} // end class StudentPoll

/*

java.lang.ArrayIndexOutOfBoundsException: 14
responses[19] = 14

Rating    Frequency
1         3
2         4
3         8
4         2
5         2

*/