java - Algorithms for string processing -

i have question make me think how improve speed , memory of system. describe example, have file have string:

<e>customer</e>     <a1>customer id</a1>     <a2>customer name</a2> <e>person</e> 

it similar xml file.

now, solution when read <e>customer</e>, read nearest tag , then, substring <e>customer</e> nearest tag.

it make system need process much. used regular expression it. thought same real compiler have phases (lexical analysis, parser).

any ideas?

thanks in advance!

if don't want use 1 of free , reliable xml parsers fast solution involve state machine.

see how create simple state machine in java question start.

please sure have very reason taking route.