FileHasher.java

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

import java.io.IOException;
import java.io.FileNotFoundException;
import java.lang.NullPointerException;
import java.security.NoSuchAlgorithmException;


public class FileHasher{
    public static void main(String[] args){
        if(args.length == 2){
            String algorithm = args[0];
            String file = args[1];
            String output = "";
            if(!(algorithm.equalsIgnoreCase("MD5") || algorithm.equalsIgnoreCase("SHA-1"))){
                System.out.println("Hashing algorithm must be \"MD5\" or \"SHA-1\" only.");
            } else {
                FileHasher newFH = new FileHasher();
                try{
                    output = newFH.getHash(file, algorithm);
                } catch (NullPointerException npe) {
                    System.out.println("Oops ... Something hinkey happened: " + npe);
                }
                System.out.println(output + "  " + file);
            }
        } else {
            System.out.println("Usage: bfilehasher hash_algorithm file_path ");
        }
    }

    public String getHash(String inFile, String hashingAlgorithm) throws NullPointerException {
        int base = 16;
        byte[] myByteArray = null;
        byte[] finalByteArray = null;
        String MDHash = hashingAlgorithm;
        String fileHash = "";
        FileInputStream myFIS = null;
        BigInteger newBI;
        MessageDigest myMD;


        try {
            myFIS = new FileInputStream(inFile);
        } catch (FileNotFoundException fnfe) {
            System.out.println("Oops ... Something hinkey happened: " + fnfe);
        }

        try {
            myByteArray = new byte[myFIS.available()];
            myFIS.read(myByteArray);
        } catch (IOException ioe) {
            System.out.println("Oops ... Something hinkey happened: " + ioe);
        }

        try {
            myMD = MessageDigest.getInstance(MDHash);
            myMD.update(myByteArray);
            finalByteArray = myMD.digest();
        } catch (NoSuchAlgorithmException nsae) {
            System.out.println("Oops ... Something hinkey happened: " + nsae);
        }

        newBI = new BigInteger(1, finalByteArray);
        fileHash = newBI.toString(base);

        return fileHash;

    }
}