如何使用正则表达式查找密码

Question

A password consists of digits and Latin letters in any case; a password always follow by the "password" word (in any case), but they can be separated by any number of spaces and the colon: characters.

I try this regular expression

Pattern pattern = Pattern.compile("password\\s\\w*",Pattern.CASE_INSENSITIVE);

If text is

    String text = "My email javacoder@gmail.com with password    SECRET115. Here is my old PASSWORD: PASS111.\n";//scanner.nextLine();

We need to find SECRET115 and PASS111. Now program fails and cannot find pattern.

Answer 1

You may add an optional : after password , and match 0 or more whitespaces with \s* :

password:?\s*(\w+)

See the regex demo .

Details

• password - a fixed string
• :? - 1 or 0 colons
• \s* - 0+ whitespaces
• (\w+) - Capturing group 1: one or more word chars.

Java demo :

String s = "My email javacoder@gmail.com with password    SECRET115. Here is my old PASSWORD: PASS111.\n";
Pattern pattern = Pattern.compile("password:?\\s*(\\w+)", Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(s);
while (matcher.find()){
    System.out.println(matcher.group(1)); 
} 

Output:

SECRET115
PASS111