guava/src/com/google/common/io/LittleEndianDataOutputStream.java
@Override
  public void writeLong(long v) throws IOException {
    byte[] bytes = Longs.toByteArray(Long.reverseBytes(v));
    write(bytes, 0, bytes.length);
  }
@Override
  public void writeLong(long v) throws IOException {
    byte[] bytes = Longs.toByteArray(Long.reverseBytes(v));
    write(bytes, 0, bytes.length);
  }
Writes a {@code long} as specified by {@link DataOutputStream#writeLong(long)}, except using
little-endian byte order.

@throws IOException if an I/O error occurs