title: Extending ByteBuffer class
body: <p>Is there any way to create class that extends ByteBuffer class?</p>
  
  <p>Some abstract methods from ByteBuffer are package private, and if I create package java.nio, security exception is thrown.</p>
  
  <p>I would want to do that for performance reasons - getInt for example has about 10 method invocations, as well as quite a few if's. Even if all checks are left, and only method calls are inlined and big/small endian checks are removed, tests that I've created show that it can be about 4 times faster.</p>