Convert a byte array to a human-readable String for debugging purposes. : Byte Array « File « Java Tutorial

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3. Byte Array

import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Properties;

/*

   Derby - Class org.apache.derby.iapi.util.PropertyUtil

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to you under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */



public class Main {

  private static char[] hex_table = {
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 
    'a', 'b', 'c', 'd', 'e', 'f'
};
  /**
    Convert a byte array to a human-readable String for debugging purposes.
  */
  public static String hexDump(byte[] data)
  {
            byte byte_value;


            StringBuffer str = new StringBuffer(data.length * 3);

            str.append("Hex dump:\n");

            for (int i = 0; i < data.length; i += 16)
            {
                // dump the header: 00000000: 
                String offset = Integer.toHexString(i);

                // "0" left pad offset field so it is always 8 char's long.
                for (int offlen = offset.length(); offlen < 8; offlen++) 
                    str.append("0");
                str.append(offset);
                str.append(":");

                // dump hex version of 16 bytes per line.
                for (int j = 0; (j < 16) && ((i + j) < data.length); j++)
                {
                    byte_value = data[i + j];

                    // add spaces between every 2 bytes.
                    if ((j % 2) == 0)
                        str.append(" ");

                    // dump a single byte.
                    byte high_nibble = (byte) ((byte_value & 0xf0) >>> 4); 
                    byte low_nibble  = (byte) (byte_value & 0x0f); 

                    str.append(hex_table[high_nibble]);
                    str.append(hex_table[low_nibble]);
                }

                // dump ascii version of 16 bytes
                str.append("  ");

                for (int j = 0; (j < 16) && ((i + j) < data.length); j++)
                {
                    char char_value = (char) data[i + j]; 

                    // RESOLVE (really want isAscii() or isPrintable())
                    if (Character.isLetterOrDigit(char_value))
                        str.append(String.valueOf(char_value));
                    else
                        str.append(".");
                }
                    
                // new line
                str.append("\n");
            }
            return(str.toString());

  }



}