Object Oriented Programming Articles - Page 857 of 915

Java Regex Capturing Groups

Capturing groups are a way to treat multiple characters as a single unit. They are created by placing the characters to be grouped inside a set of parentheses. For example, the regular expression (dog) creates a single group containing the letters "d", "o", and "g".Capturing groups are numbered by counting their opening parentheses from the left to the right.In the expression ((A)(B(C))), for example, there are four such groups -((A)(B(C)))(A)(B(C))(C)Back references allow repeating a capturing group using a number like \# where # is the groupnumber. See the example below −ExampleLive Demoimport java.util.regex.Matcher; import java.util.regex.Pattern; public class Tester {   ... Read More

https://www.tutorialspoint.com/javaregex/javaregex_capturing_groups.htm

ExampleLive Demoimport java.util.regex.Matcher; import java.util.regex.Pattern; public class NoRegTest {    public static void main(String[] args) {       String s="^fun";       Pattern pattern = Pattern.compile(s);       Matcher matcher = pattern.matcher("Java is fun");       if(!matcher.find()) {          System.out.println("not found");       }    } }Outputnot found

In this program, we will use a regular expression to check if a given string does not contain the substring "kk" using Java. The regular expression ^((?!kk).)*$ is designed to match strings that do not include the "kk" pattern anywhere in the string. The program will evaluate a sample string and print whether or not it contains "kk". Problem Statement Write a program in Java for checking whether a given string contains the substring "kk." If the string does not contain "kk" the program will return true otherwise it will return false. Input String s = "tutorials" Output true ... Read More

Exampleimport java.util.regex.*; class PatternMatch{    public static void main(String args[]) {       String content = "I am a student";       String string = ".*boy.*";       boolean isMatch = Pattern.matches(string, content);       System.out.println("The line contains 'boy'?"+ isMatch);    } }Outputthe line contains 'boy'?falsematches()­­It is used to check if the whole text matches a pattern. Its output is boolean. It returns true if match is found otherwise false.This is one of simplest and easiest way of searching a String in a text using Regex .There is a another method compile() , if you want ... Read More

\R matches any line break as defined by the Unicode standardPattern p = Pattern.compile("\R");Unicode line-break sequence is equivalent to \u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]

In Java regex matches() matches the input string against the whole string as it add a ^ and $ at the end of the input string.so it will not match the substring. So for matching substring, you should use find().Exampleimport java.util.regex.*; class PatternMatchingExample {    public static void main(String args[]) {       String content = "aabbcc";       String string = "aa";       Pattern p = Pattern.compile(string);       Matcher m = p.matcher(content);       System.out.println(" 'aa' Match:"+ m.matches());       System.out.println(" 'aa' Match:"+ m.find());    } }Output'aa' Match:false 'aa' Match:true

ExampleLive Demoimport java.util.ArrayList; import java.util.List; import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class SearchRegex {    private Pattern subPattern = Pattern.compile(SUBJECT_PATTERN);    private Matcher matcher;    private static final String SUBJECT_PATTERN = "(?s)Subject 1:\s(.*)Subject 2:";    public static void main(String[] args) {       String d = "Subject 1: Java" + "Subject 2: Python";       SearchRegex obj = new SearchRegex();       List list = obj.getSubject(d);       System.out.println("Address Result : " + list);    }    private List getSubject(String d){       List result = new ArrayList();       matcher = subPattern.matcher(d);       while (matcher.find()) {          result.add(matcher.group(1));       }       return result;    } }OutputAddress Result : [Java]

the syntax? i:x makes the string search case-insensitive. for egpublic class RegCaseSense {    public static void main(String[] args) {       String stringSearch = "HI we are at java class.";       // this won't work because the pattern is in upper-case       System.out.println("Try this 1: " + stringSearch.matches(".*CLASS.*"));         // the magic (?i:X) syntax makes this search case-insensitive, so it returns true       System.out.println("Try this 2: " + stringSearch.matches("(?i:.*CLASS.*)"));    } }