content: /*
   * Copyright (C) 2016 The Android Open Source Project
   *
   * Licensed 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.
   */
  
  package com.android.apksigner;
  
  import java.nio.ByteBuffer;
  
  /**
   * Hexadecimal encoding where each byte is represented by two hexadecimal digits.
   */
  class HexEncoding {
  
      /** Hidden constructor to prevent instantiation. */
      private HexEncoding() {}
  
      private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();
  
      /**
       * Encodes the provided data as a hexadecimal string.
       */
      public static String encode(byte[] data, int offset, int length) {
          StringBuilder result = new StringBuilder(length * 2);
          for (int i = 0; i < length; i++) {
              byte b = data[offset + i];
              result.append(HEX_DIGITS[(b >>> 4) & 0x0f]);
              result.append(HEX_DIGITS[b & 0x0f]);
          }
          return result.toString();
      }
  
      /**
       * Encodes the provided data as a hexadecimal string.
       */
      public static String encode(byte[] data) {
          return encode(data, 0, data.length);
      }
  
      /**
       * Encodes the remaining bytes of the provided {@link ByteBuffer} as a hexadecimal string.
       */
      public static String encodeRemaining(ByteBuffer data) {
          return encode(data.array(), data.arrayOffset() + data.position(), data.remaining());
      }
  }
  