Simple Positive Lookahead : Pattern « Regular Expressions « Java

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Java » Regular Expressions » Pattern Screenshots  Simple Positive Lookahead   import java.util.regex.Matcher; import java.util.regex.Pattern; public class Main {   public static void main(String args[]) {     String regex = "(?=^255).*";     Pattern pattern = Pattern.compile(regex);     String candidate = "255.0.0.1";     Matcher matcher = pattern.matcher(candidate);     String ip = "not found";     if (matcher.find())       ip = matcher.group();     String msg = "ip: " + ip;     System.out.println(msg);   } }        Related examples in the same category 1.  Simple Pattern 2.  Pattern Match 3.  Pattern Split 4.  Another pattern split 5.  Reg Exp Example 6.  PatternConvenience -- demonstrate java.util.regex.Pattern convenience routine 7.  Simple example of using Regular Expressions functionality in String class 8.  Show use of Pattern.CANON_EQ 9.  A block of text to use as input to the regular expression matcher 10.  Allows you to easily try out regular expressions 11.  Regular expressions: start End 12.  Pattern: Resetting 13.  Pattern: flags 14.  Setting Case Sensitivity in a Regular Expression 15.  Use enclosing form 16.  Use a character set 17.  Adding Comments to a Regular Expression 18.  The inline modifier can also contain pattern characters using the form (?x:abc) 19.  Use an inline modifier: (?x)a [\\ ] b 20.  Use an inline modifier: x)a \\s b 21.  Use an inline modifier: a (?x: b) 22.  Tabs and newlines in the pattern are ignored as well 23.  Compiling a Pattern with Multiple Flags 24.  Matching Across Line Boundaries in a Regular Expression 25.  Match Duplicate Words 26.  Validation Test With Pattern And Matcher 27.  Match one or more 28.  Matcher.reset: restart 29.  Matcher.reset(CharSequence) 30.  Matcher.start(): Find the starting point 31.  Matcher.start(int) Example 32.  Matcher.end(): find the end point 33.  Find the end point of the second 'test' 34.  Using the find() Method from Matcher 35.  Using the find(int) Method 36.  Using the lookingAt Method 37.  Possessive Qualifier Example 38.  Finding Every Occurrence of the Letter A 39.  Simple Negative Lookahead 40.  Simple Positive Lookbehind 41.  Regular expression search program 42.  Find all matches 43.  Implement a pattern matcher for regular expressions 44.  Regular expression and CharSequence 45.  Regular Expression search and replace program 46.  Pattern helper