How to remove consonants from a string using regular expressions in Java?

The simple character class “[ ]” matches all the specified characters in it. The meta character ^ acts as negation within the above character class i.e. the following expression matches all the characters except b (including spaces and special characters)

"[^b]"

Similarly, the following expression matches all the consonants in the given input string.

"([^aeiouyAEIOUY0-9\W]+)";

Then you can remove the matched characters by replacing them with the empty string “”, using the replaceAll() method.

Example 1

public class RemovingConstants {    public static void main( String args[] ) {       String input = "Hi welc#ome to t$utori$alspoint";       String regex = "([^aeiouAEIOU0-9\W]+)";       String result = input.replaceAll(regex, "");       System.out.println("Result: "+result);    } }

Output

Result: i e#oe o $uoi$aoi

Example 2

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RemovingConsonants {    public static void main( String args[] ) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter input string: ");       String input = sc.nextLine();       String regex = "([^aeiouyAEIOUY0-9\W])";       String constants = "";       //Creating a pattern object       Pattern pattern = Pattern.compile(regex);       //Matching the compiled pattern in the String       Matcher matcher = pattern.matcher(input);       //Creating an empty string buffer       StringBuffer sb = new StringBuffer();       while (matcher.find()) {          matcher.appendReplacement(sb, "");       }       matcher.appendTail(sb);       System.out.println("Result: \n"+ sb.toString() );    } }

Output

Enter input string: # Hello how are you welcome to Tutorialspoint # Result: # eo o ae you eoe o uoiaoi #