Java001

package test;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.swing.JOptionPane;



    public class BytesExample
    {
    public static byte[] getBytesFromFile(File file) throws IOException {
        InputStream fileInputStream = new FileInputStream(file);
        // Get the size of the file
        long length = file.length();
        // You cannot create an array using a long type.
        // It needs to be an int type.
        // Before converting to an int type, check
        // to ensure that file is not larger than Integer.MAX_VALUE.
        if (length > Integer.MAX_VALUE) {

        }
        // Create the byte array to hold the data
        byte[] bytes = new byte[(int)length];
        // Read in the bytes
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
               && (numRead=fileInputStream.read(bytes, offset, bytes.length-offset)) >= 0) {
            offset += numRead;
        }
        // Ensure all the bytes have been read in
        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "+file.getName());
        }
        // Close the input stream and return bytes
        fileInputStream.close();
        return bytes;
        }
        public static String getHexString(byte[] b) throws Exception
        {
            String result = "";
            for (int i=0; i < b.length; i++)
            {
                    result +=
                    Integer.toString( ( b[i] & 0xff ) + 0x100, 16).substring( 1 );
            }
        return result;
        }
        public static void main(String args[])
        {
            try
            {
                File file = new File("output.txt");
                byte[] arrayOfBytes = getBytesFromFile(file);

                System.out.println(Integer.toBinaryString( (int) arrayOfBytes[1]));
                System.out.println(getHexString(arrayOfBytes));
            }
            catch (IOException e)
            {
                JOptionPane.showMessageDialog(null,
                         e.getMessage() +
                               "\nError while dealing with files" ,
                                   "\n... ",
                                       JOptionPane.PLAIN_MESSAGE);
            }
            catch (Exception e)
            {
                JOptionPane.showMessageDialog(null,
                         e.getMessage() +
                               "\nKError while converting bytes to String" ,
                                   "\n... ",
                                       JOptionPane.PLAIN_MESSAGE);
            }
        }

    }