寻找正则表达式的建议

Question

I'm trying to create a regex which has to match these patterns: \\n 700000000123

I mean this "\\n"+"white space"+"12 digits"

So I tried:

(\\\\\\\\)(n)(\\\\s)(\\\\d{12})

or something like this:

(\\\\\\\\)(n)(\\\\s)(\\\\[0-9]{12})

But it still doesn't work. for me {12} means repeat a digit \\d or [0-9] , 12 times ?

My idea is a java code which could check if a string contains this regex:

Boolean result = false;

String string_to_match = "a random string \n 700000000123"
String re1="(\\\\)";    
String re2="(n)";   
String re3="(\\s)"; 
String re4="([0-9]{11})";   

Pattern p = Pattern.compile(re1+re2+re3+re4, Pattern.CASE_INSENSITIVE | Pattern.DOTALL);

if (string_to_match.contains(p.toString()){
      result = true;
}

I tried to use: http://www.txt2re.com/ to help me.

Have you any advices to build this regex ? I would like to understand why at the moment it doesn't work.

Answer 1

You need to use String#matches instead of String#contains to match a regex.

Following should work:

String re1="(\\n)";    
String re2="( )"; 
String re3="(\\d{12})";   

Pattern p = Pattern.compile(re1+re2+re3, Pattern.CASE_INSENSITIVE | Pattern.DOTALL);
System.out.println("\n 700000000123".matches(p.pattern())); // true

Or simply:

System.out.println( "\n 700000000123".matches("(\n)( )(\\d{12})") ); // true

Answer 2

You can wrap it up in a chain of invocations without compromising to matching the entire input.

For instance:

String input = "\n 700000000123";
System.out.println(Pattern.compile("\n\\s\\d{12}").matcher(input).find());

Output

true

Answer 3

^\\\\n\\s+\\d{12}$

I guess this should work for you.See demo.

https://regex101.com/r/eZ0yP4/33

Answer 4

\\n will work only in Unix machines. In Windows it is \\r\\n. Please use System.getProperty("line.separator") if you want your code to work both in linux and windows.

Use the following

System.out.println(Pattern.compile(System.getProperty("line.separator")+"\\s\\d{12}").matcher(input).find());