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Using the or logical operator | of Java regular expressions you can match either of two given expressions.For example, if you need your regular expression should match more than one expression you can do so by separating the required expressions by “|”.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); //Regular expression to match string that starts with hello or ... Read More
The greedy quantifiers provided by Java allows you to match the multiple occurrences of an expression. Where, Exp{n} impels the occurrence of the expression exp exactly n times.Exp{n, } impels the occurrence of the expression exp at least n times.Exp{n, m} impels occurrence of the expression exp at least n and utmost m times.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample { public static void main( String args[] ) { //regular expression to accept 5 letter word String regex = "\w{5}"; Scanner sc = new Scanner(System.in); ... Read More
The meta character “^” matches the beginning of a particular string i.e. it matches the first character of the string. For example, The expression “^\d” matches the string/line starting with a digit.The expression “^[a-z]” matches the string/line starting with a lower case alphabet.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); String regex = "^[^a-zA-Z0-9//s].*"; //Compiling the ... Read More
The meta character “$” matches the end of a particular string i.e. it matches the last character of the string. For example, The expression “\d$” matches the string/line ending with a digit.The expression “[a-z]$” matches the string/line ending with a lower case alphabet.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); String regex = ".*[^a-zA-Z0-9//s]$"; //Compiling the ... Read More
To match a range of characters i.e. to match all the characters between two specified characters in a sequence you can use the character class as [a-z]The expression “[a-zA-Z]” accepts any English alphabet.The expression “[0-9&&[^35]]” accepts numbers except 3 and 5.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); String regex = "^[a-zA-Z0-9]*$"; //Compiling the regular expression ... Read More
The character classes allow you to accept a single character from a fixed set of characters. For example, The expression “[tmp]” matches the characters t or, m or, p.The expression “[^tp]” matches the characters other than t or, p.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); //Regular expression to match the characters t or, m or, p ... Read More
The meta character “.” in java regular expression matches any character (single) it could be the alphabet, number or, any special character.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); //Regular expression to match any character String regex = "."; //Compiling the regular expression Pattern pattern = Pattern.compile(regex); ... Read More
The subexpression/metacharacter “\t” matches the tab spaces.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample { public static void main( String args[] ) { String regex = "\t"; Scanner sc = new Scanner(System.in); System.out.println("Enter a string: "); String input = sc.nextLine(); Pattern p = Pattern.compile(regex); Matcher m = p.matcher(input); int count = 0; while(m.find()) { count ++; } System.out.println("Number of tab spaces: "+count); ... Read More
The subexpression/metacharacter “\b” matches the word boundaries when outside the brackets. Matches the backspace (0x08) when inside the brackets.Example 1import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample { public static void main( String args[] ) { String regex = "\bbecause\b"; Scanner sc = new Scanner(System.in); System.out.println("Enter a string: "); String input = sc.nextLine(); Pattern p = Pattern.compile(regex); Matcher m = p.matcher(input); int count = 0; while(m.find()) { count ++; ... Read More
The subexpression/metacharacter “\G” matches the point where the last match finished.Exampleimport java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample { public static void main( String args[] ) { String regex = "\G[0-9]"; Scanner sc = new Scanner(System.in); System.out.println("Enter a string: "); String input = sc.nextLine(); Pattern p = Pattern.compile(regex); Matcher m = p.matcher(input); int count = 0; String digits = ""; System.out.println("Digits in the previous match:"); while(m.find()) { ... Read More