How to check multiple regex patterns against an input? Using Java.

JavaObject Oriented ProgrammingProgramming

The "|" meta character: The meta character "|" in Java regular expressions allows you to match more than one regular expressions for example if you need to match a particular input text with more than one expression you need to separate them using it as:

exp1|exp2|exp3

Example

 Live Demo

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class SampleExample {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter your input: ");
      String input = sc.nextLine();
      //Regular expression
      String regex = "\\d{10}|^[aeiou]";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Creating a Matcher object
      Matcher matcher = pattern.matcher(input);
      if(matcher.find()) {
         System.out.println(input+" is valid");
      }else {
         System.out.println(input+" is not valid");
      }
   }
}

Output 1

Enter your input:
9848033228
9848033228 is valid

Output 2

Enter your input:
an apple a day keeps doctor away
an apple a day keeps doctor away is valid

Using List object

Another solution is that you compile all the regular expressions using individual Pattern objects and add them to a list object and find the match on the input text as −

List list = new ArrayList<>();
list.add(Pattern.compile(regex1));
list.add(Pattern.compile(regex2));
for (Pattern pattern: list) {
   Matcher matcher = pattern.matcher(input);
   if(matcher.find()) {
      . . . . . . . . . . . . . . .
   }else {
      . . . . . . . . . . . . . . .
   }
}

Example

 Live Demo

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class MultipleRegex {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter your input: ");
      String input = sc.nextLine();
      //Regular expressions
      String regex1 = "\\d{10}";
      String regex2 = "^[aeiou]";
      //Creating a pattern objects
      Pattern pattern1 = Pattern.compile(regex1);
      Pattern pattern2 = Pattern.compile(regex2);
      //Creating an List object
      List<Pattern> patterns = new ArrayList<>();
      patterns.add(pattern1);
      patterns.add(pattern2);
      for (Pattern pattern: patterns) {
         Matcher matcher = pattern.matcher(input);
         if(matcher.find()) {
            System.out.println("For regex "+pattern.pattern()+" "+input+" is valid");
         } else {
            System.out.println("For regex "+pattern.pattern()+" "+input+" is not valid");
         }
      }
   }
}

Output 1

Enter your input:
9848033228
For regex \d{10} 9848033228 is valid
For regex ^[aeiou] 9848033228 is not valid

Output 2

Enter your input:
an apple a day keeps doctor away
For regex \d{10} an apple a day keeps doctor away is not valid
For regex ^[aeiou] an apple a day keeps doctor away is valid
raja
Published on 10-Jan-2020 10:41:59
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