public   class  ooo {

     private   static  String getFileContent() {
         return  "<phonebook>\n" +
                "<entry>\n" +
                "<firstname>Mark</firstname>\n" +
                "<surname>Twain</surname>\n" +
                "<number>+375 29 632494</number>\n" +
                "</entry>\n" +
                "<entry>\n" +
                "<firstname>Jo</firstname>\n" +
                "<surname>Dirty</surname>\n" +
                "<number>+375 29 332494</number>\n" +
                "</entry>\n" +
                "<entry>\n" +
                "<firstname>Andy</firstname>\n" +
                "<surname>Ham</surname>\n" +
                "<number>+375 29 623494</number>\n" +
                "</entry>\n" +
                "</phonebook>";
    }

     public   static  String getTelNumber(String surname) {
         try  {
             return  getFileContent().toLowerCase().split("<surname>" + surname.toLowerCase(),  2 )[ 1 ].split("</number>",  2 )[ 0 ].split("<number>",  2 )[ 1 ];
        }  catch  (ArrayIndexOutOfBoundsException e) {
             return   null ;
        }
    }

    //example
     public   static   void  main(String args[]) {
        System.out.println(getTelNumber("twain"));
    }

}

 import  java.util.HashMap;
 import  java.util.HashSet;
 import  java.util.Set;

 public   class  PhoneBook {

     private  HashMap<String, Set<BookEntry>> cache =  new  HashMap<String, Set<BookEntry>>();

     class  BookEntry {
         private  String firstname;
         private  String surname;
         private  String number;

         public  String toString() {
             return  firstname + " " + surname + " " + number;
        }

         public  String getFirstname() {
             return  firstname;
        }

         public   void  setFirstname(String firstname) {
             this .firstname = firstname;
        }

         public  String getSurname() {
             return  surname;
        }

         public   void  setSurname(String surname) {
             this .surname = surname;
        }

         public  String getNumber() {
             return  number;
        }

         public   void  setNumber(String number) {
             this .number = number;
        }
    }

     public  PhoneBook() {
        String[] entries = getFileContent().split("<entry>");
         for  ( int  i =  1 ; i < entries.length; i++) {
            String tmp = entries[i];
            BookEntry entry =  new  BookEntry();
             try  {
                entry.setFirstname(tmp.split("<firstname>")[ 1 ].split("</firstname>")[ 0 ].trim());
            }  catch  (ArrayIndexOutOfBoundsException e) {/**/}
             try  {
                entry.setSurname(tmp.split("<surname>")[ 1 ].split("</surname>")[ 0 ].trim());
            }  catch  (ArrayIndexOutOfBoundsException e) {/**/}
             try  {
                entry.setNumber(tmp.split("<number>")[ 1 ].split("</number>")[ 0 ].trim());
            }  catch  (ArrayIndexOutOfBoundsException e) {/**/}

             if  (cache.containsKey(entry.getSurname())) {
                cache.get(entry.getSurname().toLowerCase()).add(entry);
            }  else  {
                HashSet<BookEntry> set =  new  HashSet<BookEntry>();
                set.add(entry);
                cache.put(entry.getSurname().toLowerCase(), set);
            }
        }

    }

     private  String getFileContent() {
        StringBuffer t = new  StringBuffer("<phonebook>\n" +
                "<entry>\n" +
                "<firstname>Mark</firstname>\n" +
                "<surname>Twain</surname>\n" +
                "<number>+375 29 632494</number>\n" +
                "</entry>\n");
         for  ( int  i =  0 ; i <  10000 ; i++) {
            t.append("<entry>\n" +
                    "<firstname>" + ( char ) i + "</firstname>\n" +
                    "<surname>" + ( char ) (i + i) + "</surname>\n" +
                    "<number>" + ( int ) (i + i /  2 ) + "</number>\n" +
                    "</entry>\n");
        }
        t.append("</phonebook>");
         return  t.toString();
    }


     public  Set<BookEntry> findEntries(String surname) {
         return  cache.get(surname.toLowerCase());
    }

    //example
     public   static   void  main(String args[]) {
        PhoneBook book =  new  PhoneBook();
         for  (BookEntry e : book.findEntries("twain")) {
            System.out.println(e);
        }
    }

}