How is a class represented in the JVM?

In class file format, basically byte stream. 64 bit data would be represented by 8 consecutive bytes. The format consists of a magic number (which identifies the format, 0xCAFEBABE), constant pool data structure (strings and interface names and class names), and access flags which denote the accessibility of the class or interface.

Access properties include:

1. ACC_PUBLIC - can be accessed from outside the package
2. ACC_FINAL - no subclasses allowed (e.g. Java3D, final methods may be inlined)
3. ACC_SUPER - treat superclass methods specially when invoked by the invokespecial instruction

Methods are represented by an array of method_info objects. These objects information on the methods accessibility (private, public, protected) and other properties (final, abstract, synchronised, strictfp). [strictfp modifier just means stick to the standard IEEE float and double data types, don't to do any widening conversions for intermediate results.] Method descriptors for each method are indexed in the constant_pool data structure for the class. A method_info object contains an index into the constant_pool.