What is MessageDigest in Java?

MessageDigest in Java is a class that allows you to generate a cryptographic hash of data, providing a way to securely store and transmit data in an irreversible manner. It is commonly used for data integrity checks, password storage, and generating unique identifiers.

        import java.security.MessageDigest;
        import java.security.NoSuchAlgorithmException;

        public class HashExample {
            public static void main(String[] args) {
                try {
                    String input = "Hello, World!";
                    MessageDigest md = MessageDigest.getInstance("SHA-256");
                    byte[] digest = md.digest(input.getBytes());
                    StringBuilder hexString = new StringBuilder();

                    for (byte b : digest) {
                        String hex = Integer.toHexString(0xff & b);
                        if (hex.length() == 1) hexString.append('0');
                        hexString.append(hex);
                    }
                    System.out.println("Hash: " + hexString.toString());
                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }
            }
        }