@Test
 public void testSerialization4() throws IOException, ClassNotFoundException {
   final MutableRoaringBitmap rr = new MutableRoaringBitmap();
   for (int k = 1; k <= 10000000; k += 10) rr.add(k);
   final ByteArrayOutputStream bos = new ByteArrayOutputStream();
   // Note: you could use a file output steam instead of
   // ByteArrayOutputStream
   int howmuch = rr.serializedSizeInBytes();
   final DataOutputStream oo = new DataOutputStream(bos);
   rr.serialize(oo);
   oo.close();
   Assert.assertEquals(howmuch, bos.toByteArray().length);
   final MutableRoaringBitmap rrback = new MutableRoaringBitmap();
   final ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
   rrback.deserialize(new DataInputStream(bis));
   Assert.assertEquals(rr.getCardinality(), rrback.getCardinality());
   Assert.assertTrue(rr.equals(rrback));
 }