java如何使用正则表达式替换N个空格

Question

I like to display a text (input text in textArea) nicely in web page. So need to

    1. change linebreaker \n to <br/>
    2. keep indentation: 
             replace 2 spaces with one space and &nbsp; 
             replace 3 spaces with one space and 2 &nbsp; 
             replace 4 spaces with one space and 3 &nbsp; 
             replace N spaces with one space and N-1 &nbsp;

Is there a way to replace the spaces using regular expression in JAVA? Thanks.

Answer 1

Underscores represent spaces:
Find: (?<=_)_
Replace:  

If you have to stick with regex, positive lookbehind is what you're looking for.
Basically, this will match each space which follows another space.

Answer 2

This should help you:

String oldString="";
String newString = oldString.replaceAll("\n", "<br />").replaceAll("(?<= ) ", "&nbsp;");