Java Basics-Regular expressions

. Any character

\d A Digit 0-9

\d a non-digit [^0-9]

\s a whitespace character, white space character

\s a non-whitespace character

\w a word character [a-za-z0-9]

\w a Non-word character

Package Dao;import Java.util.regex.matcher;import Java.util.regex.pattern;public class Testreg {public static void main  (string[] args) throws Exception{/*system.out.println ("abc". Matches ("...");  True ctrl+shift+/comment System.out.println ("a898938593a". ReplaceAll ("\\d", "-"));    A---------Apattern p = pattern.compile ("[A-z]{3}"); Matches a string with 3 characters matcher m = P.matcher ("abc");          System.out.println (M.matches ()); true*///preliminary understanding. * +?, Meta characters/*p ("a". Matches (".")); True P ("AA". Matches ("AA"));   True P ("AAAA". Matches ("A *")); True 0 or NP ("AAAA". Matches ("A +")); True 1 or NP ("AAAA". Matches ("A?"));    False 0 or 1p ("". Matches ("*")); True 0 or NP ("". Matches ("A +"));    True 1 or NP ("". Matches ("A?"));    True 0 or 1p ("215454545454545". Matches ("\\d{3,100}"));           True 3~100 a P ("192.168.000.111". Matches ("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}"));  TRUEP ("192". Matches ("[0-2][0-9][0-9]"));       true*///Range/*p ("a". Matches ("[ABC]")); True [] takes out aCharacter P ("a". Matches ("[^ABC]"));       False [] takes out a character p ("a". Matches ("[A-za-z]")); True [] takes out a character p ("a". Matches ("[a-z]|[       A-z] "));       True [] takes out a character p ("a". Matches ("[A-z[a-z]")); True [] takes out a character p ("R". Matches ("[a-z&&|[       RFG]]);  True [] Take out a character *///recognize \s \w \d/*p ("\n\r\t". Matches ("\\s{4}"));   True 4 whitespace characters P ("". Matches ("S"));  False S stands for non-whitespace characters p ("A_8". Matches ("\\w{3}"));  TRUEP ("abc888&^%". Matches ("[a-z]{1,3}\\d+[&^$%]+"));  True 1-3 letters, 1 or n digits, [&^$%] any 1 or n p ("\ \". Matches ("\\\\"));  In regular expressions, 2 \ \ Only represents an escape character *///posix Style//p ("a". Matches ("\\p{lower}"));//boundary/*p ("Hello Sir". Matches ("^h.*"));  Truep ("Hello Sir". Matches (". *ir$"));  Truep ("Hello Sir". Matches ("^h[a-z]{1,3}o\\b.*"));  TRUEP ("Hellosir". Matches ("^h[a-z]{1,3}o\\b.*"));  True \b is a space, newline, and other word boundaries *///white lines blank lines//p ("\ n". Matches ("^[\\s&&[^\\n]]*\\n$"));  True begins with a whitespace character, and is not a carriage return, 0 or n times, followed by a newline character//practice/*p ("AAA 8888c". Matches (". *\\d{4}.")); True 0 or n letters, 4 digits,Then there is a letter P ("AAA 8888c". Matches (". *\\b\\d{4}."));  True 0 or n letters, 4 digits preceded by a word boundary, and then there is a letter P ("aaa8888c". Matches (". *\\d{4}."));  True 0 or n letters, 4 digits, and then there is a letter P ("aaa8888c". Matches (". *\\b\\d{4}.")); False 0 or n letters, 4 digits before the word boundary, and then there is a letter *///email//p ("[email protected]". Matches ("[\\w[.-]][email  Protected][\\w[.-]]+\\.  [\\w]+ ")); True//matches find Lookingat start end matches each time you find the entire string, find a string, lookingat each time to find/*pattern p = pattern.compile (" \\d{3,5} "); String s = "123-34345-234-00"; Matcher m = P.matcher (s);p(m.matches ()); Put 123-to eat, so to reset the following.      Otherwise, if not reset, then only 2 true 34345 234m.reset ();  To restore the characters eaten by matches to P (M.find ());  True to find a matching string 123p (M.start () + "-" +m.end ()); 0-3p (M.find ());  True to find a matching string 34345p (M.start () + "-" +m.end ());  4-9p (M.find ());//true find a matching string 234p (M.start () + "-" +m.end ());  10-13p (M.find ());  False 00p (M.lookingat ());  True only starts from head, so it is 123p (M.lookingat ());  True only starts from head, so it is 123p (M.lookingat ());  True only starts from head, so it is 123p (M.lookingat ());True only starts from head, so it is 123*///replacementpattern p = pattern.compile ("java", pattern.case_insensitive); Matcher m = P.matcher (Java java java Ilovejava you hatejava);  StringBuffer buf = new StringBuffer (); int i=0;/*while (M.find ()) {p (M.group ());   List all Java words in}*/while (M.find ()) {i++;if (i%2==0) {m.appendreplacement (buf, "Java");  The even numbers are java}else{m.appendreplacement (buf, "JAVA");//Odd are Java}}m.appendtail (BUF);p(buf); Lists all Java words for}public static void P (Object o) {System.out.println (o);}}

　　

Java Basics-Regular expressions