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

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 smaller than that for capital B. Thus alphabetic order is actually ascending order.

Bubble Sort:

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 ] );

      }

      public static void sortStringBubble( String  x [ ] )

      {

            int j;

            boolean flag = true;  //to 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];

                                      x [ j+1] = temp;

                                      flag = true;

                           } // end if

                   } // end for

            } // end while

      } // end sortArray

}

Exchange Sort:

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 ] );

      }

      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 ];

                                      x [ j ] = temp;

                           } // end if

                   } // end for

             } // end for

      } // end sortArray