Java positive expressions matching, replacing, finding, cutting methods _ regular expressions

Regular expression lookup, mainly used to split () in string class;

String str;

Str.split (); In the method to intercept by what rule, return a string array

Common rules for intercepting:

Str.split ("\.") Follow. to intercept.

Str.split ("") Intercept by Space

Str.split ("cc+") in accordance with the C character intercept, 2 C or more

Str.split ((1) \\.+) in the string containing 2 characters or more places to intercept (1) indicates that the group is 1

Examples of interception;

To intercept in accordance with a group; a position in two or more two places.

String str = "Publicstaticccvoidddmain"; 
   Reusing a String ragex1= for an expression in a group 
   (.) \\1+ "; 
   string[] ss = Str.split (RAGEX1);
   for (String st:ss) {
   System.out.println (ST); 
   }
Intercept
String Ragex = "" according to two cc+; 
  Cutting 
   String STRs = "Publicstaticccvoidddmain"; 
  String Ragexs = "cc+";
  String[] s = strs.split (Ragexs);
  for (String ssss:s) {
  System.out.println (SSSS);
  }
  System.out.println ("=-=========");

substitution in regular expressions;

Syntax definition rules;

String s =str.replaceall (Ragex, NEWSTR);

The substitution in the string is replace ();

Replace 4 or 4 consecutive digits with *

Replace
   String str= "wei232123jin234";
   String Ragex = "\\d{4,}";
   String newstr = "*";
   String s =str.replaceall (Ragex, newstr);
   System.out.println (s);

Replace the duplicate string with a *

String str = "wwweiei222222jjjiiinnn1232";
   String Ragex = "(.) \\1+ ";
   String newstr = "*";
   String s = Str.replaceall (Ragex, newstr);
   System.out.println (s);

Will I ... I... To.. To eat. Eat... I'm going to eat dinner.

String str = "I ... I... To.. To eat. Eat... Rice ";
  String regex = "\\.+";
  String newstr = "";
  Str=test (str, regex, NEWSTR);
  Regex = "(.) \\1+ ";
  NEWSTR = "$";
  Test (str, regex, NEWSTR);
public static string test (String str, string regex, String newstr) {
  string str2 = Str.replaceall (regex, newstr);
  System.out.println (STR2);
  return str2;
 }

Get the string of a regular expression

1, create a Pattern object based on a defined regular expression

2, using Pattern object class to match

3, to determine if true

4, add to Group

Example

String str = ' public static void main (string[] args) '
    + ' public static void main (string[] args) public static void Ma In (string[] args) ";
 String Ragex = "\\b[a-za-z]{4,5}\\b";
 Pattern P =pattern.compile (Ragex);
 Matcher m = p.matcher (str);
    while (M.find ()) {
    String s = m.group ();
    System.out.println (s);
    }

Homework:

1, get the user in

String str = " 
 

2, get DHFJKSADUIRFN 11@qq.com DSJHKFA wang@163.com the mailbox number in the Wokaz

String regex = ""; 
String[] Strs=str.split (regex);
 for (string str2:strs) {
 string ragexdemo = [A-za-z0-9] ([a-za-z0-9]*[-_]?[ a-za-z0-9]+) * "
 +" @ ([a-za-z0-9]+) \\.[ a-za-z]+\\.? [A-za-z] {0,2} ";
Pattern p = pattern.compile (Ragexdemo);
Matcher m = P.matcher (str2);
while (M.find ()) {
System.out.println (M.group ());
  }
 }

Sample code:

Import java.util.ArrayList;
Import Java.util.regex.Matcher;

Import Java.util.regex.Pattern; public class Test {public static void main (string[] args) {getstrings ()/////Get the specified content in the specified string content with a regular expression System.out.pr
    Intln ("********************"); Replace ();
    Replaces the string content with a regular expression System.out.println ("********************"); Strsplit ();
    Use regular expressions to cut string System.out.println ("********************"); Strmatch ();
    String match} private static void Strmatch () {String phone = "13539770000"; Check whether phone is a qualified mobile number (standard: 1 start, second for 3,5,8, 9 digits for any number) System.out.println (phone + ":" + phone.matches ("1[358][0-9]{9,9}"));
    True String str = "ABCD12345EFGHIJKLMN"; Check whether the middle of STR contains 12345 System.out.println (str + ":" + str.matches ("\\w+12345\\w+")); True System.out.println (str + ":" + str.matches ("\\w+123456\\w+")); false} private static void Strsplit () {String str = ' asfasf.sdfsaf.sdfsdfas.asdfasfdasfd.wrqwrwqer.asfsafasf.
    SAFGFDGDSG "; string[] STRs = StR.split ("\.");
    for (String s:strs) {System.out.println (s); The private static void Getstrings () {String str = "rrwerqq84461376qqasfdasdfrrwerqq84461377qqasfdasdaa65464
    5aafrrwerqq84461378qqasfdaa654646aaasdfrrwerqq84461379qqasfdasdfrrwerqq84461376qqasfdasdf "; Pattern p = pattern.compile ("QQ" (. *?)
    QQ ");
    Matcher m = p.matcher (str);
    Arraylist<string> STRs = new arraylist<string> ();      
    while (M.find ()) {Strs.add (M.group (1));
    for (String s:strs) {System.out.println (s);
    The private static void replace () {String str = "ASFAS5FSAF5S4FS6AF.SDAF.ASF.WQRE.QWR.FDSF.ASF.ASF.ASF";
    Replace the. In the string with the _, because. is a special character, so you use \. expression, and because \ is a special character, you use \ n to express it.
    str = Str.replaceall ("\.", "_");    
  System.out.println (str); }
}