content: package org.aion.precompiled.util;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.Arrays;
  
  /** Utility class for converting hex data to bytes and back again. */
  public class Hex {
  
      private static final HexEncoder encoder = new HexEncoder();
  
      public static String toHexString(byte[] data) {
          return toHexString(data, 0, data.length);
      }
  
      public static String toHexString(byte[] data, int off, int length) {
          byte[] encoded = encode(data, off, length);
          return new String(encoded);
      }
  
      /**
       * encode the input data producing a Hex encoded byte array.
       *
       * @return a byte array containing the Hex encoded data.
       */
      public static byte[] encode(byte[] data) {
          return encode(data, 0, data.length);
      }
  
      /**
       * encode the input data producing a Hex encoded byte array.
       *
       * @return a byte array containing the Hex encoded data.
       */
      public static byte[] encode(byte[] data, int off, int length) {
          ByteArrayOutputStream bOut = new ByteArrayOutputStream();
  
          encoder.encode(data, off, length, bOut);
  
          return bOut.toByteArray();
      }
  
      /**
       * Hex encode the byte data writing it to the given output stream.
       *
       * @return the number of bytes produced.
       */
      public static int encode(byte[] data, OutputStream out) {
          return encoder.encode(data, 0, data.length, out);
      }
  
      /**
       * Hex encode the byte data writing it to the given output stream.
       *
       * @return the number of bytes produced.
       */
      public static int encode(byte[] data, int off, int length, OutputStream out) {
          return encoder.encode(data, off, length, out);
      }
  
      /**
       * decode the Hex encoded input data. It is assumed the input data is valid.
       *
       * @return a byte array representing the decoded data.
       */
      public static byte[] decode(byte[] data) {
          ByteArrayOutputStream bOut = new ByteArrayOutputStream();
          try {
              encoder.decode(data, 0, data.length, bOut);
          } catch (IOException e) {
              System.err.println("Hex decode failed! " + Arrays.toString(data));
              return null;
          }
  
          return bOut.toByteArray();
      }
  
      /**
       * decode the Hex encoded String data - whitespace will be ignored.
       *
       * @return a byte array representing the decoded data.
       */
      public static byte[] decode(String data) {
          ByteArrayOutputStream bOut = new ByteArrayOutputStream();
          try {
              encoder.decode(data, bOut);
          } catch (IOException e) {
              System.err.println("Hex decode failed! " + data);
              return null;
          }
          return bOut.toByteArray();
      }
  
      /**
       * decode the Hex encoded String data writing it to the given output stream, whitespace
       * characters will be ignored.
       *
       * @return the number of bytes produced.
       */
      public static int decode(String data, OutputStream out) throws IOException {
          return encoder.decode(data, out);
      }
  }
  