finally finished parsing java .class file. Although the architecture of
the parser is not good. In fact, there is no architecture or design
thoughts put into the parser. As a result, the parser's codes look
messy. Will start on part 2, which is building the interpreter tomorrow.
Thinking about the design patterns, I could have used these to organize
the parser:

Strategy: 
each section of the .class file requires a parsing's strategy. I can
have a whole package of strategy (parser) classes, one for each kind of
data ( be it Method, Class, Field...)