Java字符串替换正则表达式

Question

I am doing some string replace in SQL on the fly.

MySQLString = " a.account=b.account ";
MySQLString = " a.accountnum=b.accountnum ";

Now if I do this

MySQLString.replaceAll("account", "account_enc");

the result will be

a.account_enc=b.account_enc 

(This is good)

But look at 2nd result

a.account_enc_num=a.account_enc_num 

(This is not good it should be a.accountnum_enc=b.accountnum_enc )

Please advise how can I achieve what I want with Java String Replace.

Many Thanks.

Answer 1

From your comment:

Is there anyway to tell in Regex only replace a. account =b. account or a. accountnum =b. accountnum . I do not want accountname to be replace with _enc

If I understand correctly you want to add _enc part only to account or accountnum . To do this you can use

MySQLString = MySQLString.replaceAll("\\baccount(num)?\\b", "$0_enc");

(num)? mean that num is optional so regex will accept account or accountnum

\\\\b at start mean that there can be no letters, numbers or " _ " before account so it wont accept (affect) something like myaccount, or my_account.

\\\\b at the end will prevent other letters, numbers or " _ " after account or accountnum.

Answer 2

It's hard to extrapolate from so few examples, but maybe what you want is:

MySQLString = MySQLString.replaceAll("account\\w*", "$0_enc");

which will append _enc to any sequence of letters, digits, and underscores that starts with account .

Answer 3

try

    String s = " a.accountnum=b.accountnum ".replaceAll("(account[^ =]*)", "$1_enc");

it means replace any sequence characters which are not ' ' or '=' which starts the word "account" with the sequence found + "_enc".

$1 is a reference to group 1 in regex; group 1 is the expression in parenthesis (account[^ =]+), ie our sequence

See http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html for details