java中的正则表达式匹配

Question

Here is my example file :

lineone one
RUN lineone two
lineone three
RUN lineone four

I want to select all lines not starting with run, here is how I did it :

^([^RUN])

Is it possible to match all lines not starting with RUN and then append them to the back of the previous line ? like this

lineone one RUN lineone two
lineone three RUN lineone four

Answer 1

If your example is correct you just need to replace "\\nRUN" with " RUN" .

System.out.println(yourString.replaceAll("\nRUN", " RUN"));

Result:

lineone one RUN lineone two
lineone three RUN lineone four

ideone

Answer 2

使用str.startsWith("RUN");

Answer 3

First of all

^([^RUN]) 

does not work correctly as it will match any line that does not start with either R, U or N.

You should use lookahead:

^(?!RUN)

This should do what you want:

Pattern p = Pattern.compile("\n(RUN)", Pattern.DOTALL);
Matcher matcher = p.matcher("lineone one\nRUN lineone two\nlineone three\nRUN lineone four");
String replaceAll = matcher.replaceAll(" $1");
System.out.println(replaceAll);