java - How to convert a string from one pattern to another using regex? -


i have string want convert using regex:

aa_bb_cc_dd => ee_bb_ff_dd

tried using regex (aa)(.*)(ff). did not work. can help?

also nice if can point me regex guide. there many sites regex. not sure refer.

how about

string before = "aa_bb_cc_dd"; string after = before.replacefirst("aa(_bb_)cc(_dd)", "ee$1ff$2");  system.out.println(after); // ee_bb_ff_dd 

you haven't described how form of input string vary, difficult produce suitable regex.

if wanted allow between aa , cc use (.*?) instead of (_bb_) etc.

the above shows principle of using in replacement string content captured () , i.e. $1 refers content in first (), , $2 second ().

links:
regular-expressions.info.
the java tutorials. lesson: regular expressions.


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