import java.io.; import java.util.; import java.text.; import java.math.; import java.util.regex.; import java.security.;

public class Solution {

public static void main(String[] args) {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    Scanner s = new Scanner(System.in);
    String str;
    boolean result = false;

    while(s.hasNext()){
        str = s.nextLine().trim();
        result = Pattern.matches("^[a-zA-Z0-9]+$",str);
        if(result){
            try{
                MessageDigest md = MessageDigest.getInstance("MD5");

                md.update(str.getBytes());

                byte[] digest = md.digest();

                for(byte b : digest){
                    System.out.printf("%02x",b);
                }
                System.out.println();

            } catch (Exception e){

            }                
        } else {
            System.out.println("Invalid Input!");
        }
    }
    s.close();
}

}

works well for java7, java8, java15 import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Scanner;

public class Solution { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String s = sc.nextLine(); sc.close();

    try {
        // Create MD5 MessageDigest instance
        MessageDigest md = MessageDigest.getInstance("MD5");

        // Calculate MD5 hash in bytes
        byte[] messageDigest = md.digest(s.getBytes());

        // Convert byte array into signum representation
        StringBuilder hexString = new StringBuilder();
        for (byte b : messageDigest) {
            // Convert each byte to hexadecimal
            String hex = Integer.toHexString(0xff & b);
            if (hex.length() == 1) {
                hexString.append('0');
            }
            hexString.append(hex);
        }

        // Print the result
        System.out.println(hexString.toString());
    } catch (NoSuchAlgorithmException e) {
        // Handle exception if MD5 algorithm is not available
        throw new RuntimeException(e);
    }
}

}

import java.io.; import java.util.; import java.security.MessageDigest; import java.math.BigInteger;

public class Solution {

public static void main(String[] args) throws Exception {
    Scanner scan = new Scanner(System.in);

    String str = scan.nextLine();

    scan.close();

    try {

        // Static getInstance method is called with hashing MD5
        MessageDigest md = MessageDigest.getInstance("MD5");

        // digest() method is called to calculate message digest
        // of an input digest() return array of byte
        byte[] messageDigest = md.digest(str.getBytes());

        // Convert byte array into signum representation
        BigInteger no = new BigInteger(1, messageDigest);

        // Convert message digest into hex value
        String hashtext = no.toString(16);
        while (hashtext.length() < 32) {
            hashtext = "0" + hashtext;
        }

        System.out.println(hashtext);
    }

    // For specifying wrong message digest algorithms
    catch (Exception e) {
        throw new Exception(e);
    }

}

}