Regular Expression "re*" Metacharacter in Java

The subexpression/metacharacter “re*” matches 0 or more occurrences of the preceding expression.

Example 1

import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "aabc*";       String input = "aabcabcaabcabbcaabcbcaabc";       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       int count = 0;       while(m.find()) {          count++;       }       System.out.println("Number of matches: "+count);    } }

Output

Number of matches: 4

Example 2

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class MatchAllCharacters {    public static void main( String args[] ) {       String regex = "(.*)?(\d+)";       Scanner sc = new Scanner(System.in);       System.out.println("Enter 5 input strings: ");       String input[] = new String[5];       for (int i=0; i<5; i++) {          input[i] = sc.nextLine();       }       //Creating a Pattern object       Pattern p = Pattern.compile(regex);       System.out.println("Strings containing digits: ");       for(int i=0; i<5;i++) {          //Creating a Matcher object          Matcher m = p.matcher(input[i]);          if(m.matches()) {             System.out.println(m.group());          }       }    } }

Output

test data hello how are you 335 welcome to Tutorialspoint Strings containing digits: sample text 1 hello how are you 335