// Parsing a Date of the form: "February 24th, 2006"

import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class ParseDate
  {
  private static final SimpleDateFormat pattern = new
SimpleDateFormat( "MMM dd'th', yyyy" );

  /**
   * test harness
   *
   * @param args not used
   */
  public static void main ( String[] args )
     {

     String dateString = "February 24th, 2006";
     int where;
     if ( (where = dateString.indexOf( "st," ) ) >= 0 )
        {
        dateString = dateString.substring( 0, where)
                     + "th,"
                     + dateString.substring( where + 3 );
        }
     else if ( (where = dateString.indexOf( "nd," ) ) >= 0 )
        {
        dateString = dateString.substring( 0, where)
                     + "th,"
                     + dateString.substring( where + 3 );
        }
     Date d = null;
     try
        {
        d = pattern.parse( dateString );
        }
     catch ( ParseException e )
        {
        System.err.println( "oops:" + dateString );
        }

     System.out.println( d );

     }
  }

With JDK 1.5 you could use String.replace( "nd," ,"th," );