Hashing in Java -> Get password from hash & salt -

i have issue password hashing.

i use hashing function 1 here:

hashing java (owasp)

with function can hash passwords before save them database.

but

in application use password log in different servers (like mail-server) inside javacode need password not hashed rather plain text password.

so i'm wondering how can extract plain text password again (hash + salt stored in db , hash-function/ iteration count known) use log in different servers.

does know how that? (preferably in way can uses linked owasp code hash passwords)

edit : seems encryption way go here, acceptable solution (as encryption not safe)? go high iteration count , salt anyway.

the entire purpose of hash irreversible. if plain-text password defeat purpose of hash, , security vulnerability.