Regular Expressions match any character

The regular expression matches any character (package... today in Java, you want to use a regular expression to obtain any character in a piece of text. Therefore, the following matching rules must be written randomly: (. *) the text after the new line break cannot be obtained. So I checked the manual and found that in the regular expression, "." (DOT symbol) matches all characters except the linefeed "/N. At the same time, there is another sentence in the manual: to match any character including '/N', use a pattern like' [./N. Therefore, I modify the regular expression matching rules as follows: ([./N] *). ProgramAnd you need to change to ([. // n] *) to run the program again. I was puzzled and changed it to the following rules :([. |/n] *) and ([/n.] *) The result still does not work, and nothing can be obtained. It seems that the dot and line break are busy ~ Then I checked the Internet. Although I didn't find out what the above rule was, I found a solution. After a try, I could indeed match any character including line breaks, the following are the correct Regular Expression matching rules: ([/S] *) You can also use "([/D/d] *) "," ([/W.