Remove consonants from a string using regular expressions in Java

Simple character class " [] "Matches all specified characters. Meta-character"^It is used as a negation symbol in the above character class, meaning the following expression matches all characters except b (including spaces and special characters).

"[^b]"

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

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

Then, you can use the replaceAll() method to remove the matched characters by replacing them with an empty string "".

Example1

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:\n");+result);
　　　}
}

Output result

Result: i e#oe o $uoi$aoi

Example2

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 string:\n");
　　　　　　String input = sc.nextLine();
　　　　　　String regex = "([^aeiouyAEIOUY0-9\W])";
　　　　　　String constants = "";
　　　　　　/Create a pattern object
　　　　　　Pattern pattern = Pattern.compile(regex);
　　　　　　//Match the compiled pattern in the string
　　　　　　Matcher matcher = pattern.matcher(input);
　　　　　　//Create 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 result

Enter string:
# Hello how are you welcome to ooo #
Result:
# eo o ae you eoe o ooo #