Right to Left search in Java Regex

[Lucky J Verma]

I want to do right to left backwards search as in .net.
My regex is ^(.*\\S+.*$) .
How can i implement it in Java?In .net We have RegexOptions.RighttoLeft and Java regex engine doesnt allow backward searching.
So i am looking for alternatives.

Thanks

[prem pillai]

may be you can reverse your input & regex and then match.

Why do you want to do a reverse lookup ?

[Martin Vanyavchich]

Just as Prem Pillai said, reverse the string and then match.

StringBuilder reversed = new StringBuilder("match me").reverse();

[Lucky J Verma]

I did the same ,reversed the string and reversed it back after output.

To Pillai's Qn- I need to do Backward search because i look for a search word in a document and then pick previous 2 lines and next 2 lines and current line.
So for previous lines, i do backward matching.

How much good it is in performance wise to do this.-
reverse the string ,
reverse the pattern (I dint need this ,because i search line by line)
Mapping the index
Search and

then reverse back and also i am using collection to pick up all the lines ,reverse collection too.

Is there any other efficient method?

[Henry Wong]

Yeah... the .NET backward searching feature is nifty isn't it?

Another option, is to do a forward search, and save the results somewhere. Then use a loop that will iterate the results backwards.

Henry