Java uses regular expressions

 PackageCom.regexp;ImportJava.util.regex.Matcher;ImportJava.util.regex.Pattern; Public classTest { Public Static voidMain (string[] args) {//Regular Expressions//a "." represents an arbitrary characterP ("ABC". Matches ("...")); //"\d" represents a number, \d equivalent to not a number, the \d is reversedP ("As897as98fsg6dfg9sddf". ReplaceAll ("\\d", "_")); //Pattern can compile a schema for regular expressionsPattern p = pattern.compile ("[A-z]{3}"); Matcher m= P.matcher ("Erf"); P (m.matches ());//The matches () method is always matched to the entire string//the above three lines of code is equivalent to the following sentence, but the above three sentences performance is relatively high//{n}, must appear n times//{n,}, at least n times, up to No limit//{n,m}, appears at least n times, no more than m timesP ("QQQ". Matches ("[A-z]{3}"))); //preliminary understanding of ".", "*", "+", "?" Matadata (source data)P ("a". Matches ("."));//an arbitrary characterP ("AA". Matches ("AA"))); P ("AAAA". Matches ("A *"));//0 or moreP ("AAAA". Matches ("A +"));//1 or moreP ("AAAA". Matches ("A?"));//1 or not presentP ("". Matches ("A?"));//0 Width MatchingP ("a". Matches ("a?"))); P ("45913549872168435". Matches ("\\d{3,10}")); P ("192.168.0.222". Matches ("\\d{1,3}.\\d{1,3}.\\d{1,3}.\\d{1,3}")); P ("192". Matches ("[0-2][0-9][0-9]")); //RangeP ("a". Matches ("[ABC]"));//[] refers to matching a character, no matter how long it is writtenP ("L". Matches ("[^ABC]"));//"^" other than ABC can matchP ("a". Matches ("[A-za-z]"));//"-" indicates from which range to which range (this means lowercase or uppercase letters)P ("a". Matches ("[a-z]|[ A-z] "));//Ibid .P ("a". Matches ("[a-z[a-z]]"));//Ibid .P ("R". Matches ("[A-Z&&[RFG]]");//colleagues meet two scopes//meet \d \s \\u \P ("\n\t\r". Matches ("\\s{4}"));//"\s" is a blank character, such as a space, line break, tab, etc.P ("FA". Matches ("\\s{1,8}"));//" \s" is the inverse of "\s "P ("A_8". Matches ("\\w{3}"));//"\w" refers to a character that can be used as a name: uppercase and lowercase underscores + numbersP ("abc807$%". Matches ("[a-z]{1,3}\\d+[&^%$]+"))); P ("\ \". Matches ("\\\\"))); //Boundary Matching DeviceP ("Hello sir". Matches ("^h.*"));//"^" represents the beginning of a line when it is outside "[]" .P ("Hello sir". Matches (". *ir$"));//"$" is put at the end of the end of the line represented byP ("Hello#sir". Matches ("^h[a-z]{3}o\\b.*"));//the "\b" word boundary can include those whitespace characters or "\w", etc.P ("Hellosir". Matches ("^h[a-z]{3}o\\b.*"))); //Filter Blank Lines ("*" is used to decorate "^[\\s&&[^\\n]")P ("\ t \ n". Matches ("^[\\s&&[^\\n]]*\\n$"))); //Email AddressP ("[email protected]". Matches ("[\\w[.-]][email protected][\\w[.-]]+.[ \\w]+ ")); //The Matches.find () method is to find substrings in a string that conform to a regular expression//Regular Expression search engines need to be aware of a pointPattern P1 = Pattern.compile ("\\d{3,5}"); String s= "123-4567-8912-12345-ac"; P ("Total length of string:" +s.length ()); Matcher M1=P1.matcher (s);        P (m1.matches ()); //when the previous line of code is executed, the regular expression engine has already matched string s, and several subsequent find () methods are from "4567 ..." Started looking.//This means that the find () method and the matches () are mutually affectedM1.reset ();//call the Reset () method to resolve the mutual effects of find and matchesP (M1.find ()); P (M1.start ()+"----------"+m1.end ());        P (M1.find ()); P (M1.start ()+"----------"+m1.end ());        P (M1.find ()); P (M1.start ()+"----------"+m1.end ());        P (M1.find ()); P (M1.start ()+"----------"+m1.end ());        P (M1.find ()); //If you want to output the location of the substring found, if you must be able to find, otherwise execute the following line of code will be an error!P (M1.start () + "----------" +m1.end ()); //The Lookingat () method is to find the entire string from the start positionP (M1.lookingat ());        P (M1.lookingat ());        P (M1.lookingat ());                P (M1.lookingat ()); //simply do an exercise to find out all the URLsString News = "The People's livelihood in the diligent, diligent is not the Chamber www.baidu.com--Xi greatly used more than 2000 years ago," left biography "in the old adage www.sina.com.cn interpretation of the most simple truth. "+" 2013spring.io April 28, "+" Xi greatly in the National Federation of Trade Unions and the national www.qq.com model worker representatives, stressed that "+" must be firmly established Www.hanqi.net Labor is the most glorious, the highest work, the greatest labor, the most beautiful concept of labor, advocating labor, the benefit of workers, "+" let the whole people further glow of labor enthusiasm, release to create news.ifeng.com potential, through labor to create a better life. ";                SYSTEM.OUT.PRINTLN (news); Pattern P2= Pattern.compile ("[[a-z][.]] +[\\w]+ "); Matcher m2=P2.matcher (News);  while(M2.find ()) {//p (news.substring (M2.start (), M2.end ()));P (M2.group ()); }                //Substitution of strings//Pattern.case_insensitive (a constant in Pattern, ignoring case)Pattern p3 = pattern.compile ("java", pattern.case_insensitive); String S1= "Java Java java java I like Java qwert"; Matcher M3=P3.matcher (S1); intB=0; StringBuffer buf=NewStringBuffer ();  while(M3.find ()) {//ReplaceAll directly returns the entire string that has been replaced//p (M.replaceall ("Java"));b++; //If you want to convert an even bit of Java to lowercase, the odd digits are replaced with uppercase            if(b%2==0) {m3.appendreplacement (buf,"Java"); } Else{m3.appendreplacement (buf,"JAVA");        }} m.appendtail (BUF);            P (buf.tostring ()); //Grouping of regular Expressions//application: In the following example, if you want to take out each of the matching strings, you also want to take out a string that is just a number//You can use grouping, grouping rules, from left to right number of "(", that is, the first few groupsPattern P4 = Pattern.compile ("((\\d{3,5}) ([a-z]{2})]"); String S2= "123av-4567aa-8912qq-12345vv-ac"; Matcher M4=p4.matcher (S2);  while(M4.find ()) {p (M4.group (3)); }    }         Public Static voidp (Object o) {System.out.println (o); }}

Java uses regular expressions