8.  将一个数组列表转换为数组
  String[] stringArray = { "a", "b", "c", "d", "e" };
  ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray));
  String[] stringArr = new String[arrayList.size()];
  arrayList.toArray(stringArr);
  for (String s : stringArr)
  System.out.println(s);
  9.  将一个数组转换为集(set)
  Set<String> set = new HashSet<String>(Arrays.asList(stringArray));
  System.out.println(set);
  //[d, e, b, c, a]
  10.  逆向一个数组
  int[] intArray = { 1, 2, 3, 4, 5 };
  ArrayUtils.reverse(intArray);
  System.out.println(Arrays.toString(intArray));
  //[5, 4, 3, 2, 1]
  11.  移除数组中的元素
  int[] intArray = { 1, 2, 3, 4, 5 };
  int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array
  System.out.println(Arrays.toString(removed));
  12.  将整数转换为字节数组
  byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
  for (byte t : bytes) {
  System.out.format("0x%x ", t);
  }