Implementing in-memory compression for objects in Java

If you want to compress instances of MyObject you could have it implement Serializable and then stream the objects into a compressed byte array, like so:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
GZIPOutputStream gzipOut = new GZIPOutputStream(baos);
ObjectOutputStream objectOut = new ObjectOutputStream(gzipOut);
objectOut.writeObject(myObj1);
objectOut.writeObject(myObj2);
objectOut.close();
byte[] bytes = baos.toByteArray();

Then to uncompress your byte[] back into the objects:

ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
GZIPInputStream gzipIn = new GZIPInputStream(bais);
ObjectInputStream objectIn = new ObjectInputStream(gzipIn);
MyObject myObj1 = (MyObject) objectIn.readObject();
MyObject myObj2 = (MyObject) objectIn.readObject();
objectIn.close();