Java MD5 Hash Sample

MD5 (Message Digest) is an encryption algorithm that creates a unique hash from a given data which is completely reverseble. This means you cannot recalculate original data using its hash , and hash is universally unique.

Here is a sample code that produces MD5 hash of a given string :

package javacream;

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

public class MD5HashTest {

 private static String getMD5Digest(String str) {
  try {
   byte[] buffer = str.getBytes();
   byte[] result = null;
   StringBuffer buf = null;
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   //allocate room for the hash 
   result = new byte[md5.getDigestLength()];
   //calculate hash 
   md5.reset();
   md5.update(buffer);

   result = md5.digest();
   System.out.println(result);
   //create hex string from the 16-byte hash 
   buf = new StringBuffer(result.length * 2);
   for (int i = 0; i < result.length; i++) {
    int intVal = result[i] & 0xff;
    if (intVal < 0x10) {
     buf.append("0");
    }
    buf.append(Integer.toHexString(intVal).toUpperCase());
   }
   return buf.toString();
  } catch (NoSuchAlgorithmException e) {
   System.err.println("Exception caught: " + e);
   e.printStackTrace();

  }
  return null;
 }

 public static void main(String[] args) {
  String result = getMD5Digest("This is a text to hash");
  System.out.println("result=" + result);
 }

}