• Java provides two methods for comparing strings: compareTo and compareToIgnoreCase
  

• If s1 and s2 are String variables, then their values can be compared by s1.compareTo(s2).
  

• compareTo returns an int which is 0 if the two strings are identical, positive if s1 > s2, and negative if s1 < s2.
  

• compareToIgnoreCase operates exactly as does compareTo except that it handles mixed case strings as single case strings

ASCII (Anerican Standard Code for Information Interchange) is a standard for character encoding. It represents text in computers and other devices. (ASCII code is a subset of Unicode.)

The ASCII code chart assigns numerical values to the sequences ‘a-z’, and ‘A-Z’.  For example, the capital letter A is assigned a numerical value (065) smaller than that for capital B (066). Lower case a is assigned 097 and lower case b is assigned 098.   Thus alphabetic order is actually ascending order.

//Bubble Sort for Alphabetical Order:
public class AlphaSortingBubble
{
     public static void main(String[ ] args)
     {
             String[ ] names = {"joe", "slim", "ed", "george"};
             sortStringBubble (names);
             for ( int k = 0;  k < 4;  k++ )
                System.out.println( names [ k ] );
      }
//Method for Bubble Sort
      public static void sortStringBubble( String  x [ ] )
      {
            int j;
            boolean flag = true;  // will determine when the sort is finished
            String temp;

            while ( flag )
            {
                  flag = false;
                  for ( j = 0;  j < x.length - 1;  j++ )
                  {
                          if ( x [ j ].compareToIgnoreCase( x [ j+1 ] ) > 0 )
                          {                                             // ascending sort
                                      temp = x [ j ];
                                      x [ j ] = x [ j+1];     // swapping
                                      x [ j+1] = temp;
                                      flag = true;
                           }
                   }
            }
      }
}

//Exchange Sort for Alphabetical Order:
public class AlphaSortingExchange
{
     public static void main(String[ ] args)
     {
             String[ ] names = {"joe", "slim", "ed", "george"};
             sortStringExchange (names);
             for ( int k = 0;  k < 4;  k++ )
                System.out.println( names [ k ] );
      }
//Method for Exchange Sort
      public static void sortStringExchange( String  x [ ] )
      {
            int i, j;
            String temp;

            for ( i = 0;  i < x.length - 1;  i++ )
            {
                for ( j = i + 1;  j < x.length;  j++ )
                { 
                         if ( x [ i ].compareToIgnoreCase( x [ j ] ) > 0 )
                          {                                             // ascending sort
                                      temp = x [ i ];
                                      x [ i ] = x [ j ];    // swapping
                                      x [ j ] = temp;
                                     
                           }
                   }
             }
      }
}