Code understanding, reverse engineering, best concepts and tools. Java

Question

One of most demanding tasks for any programmer, architect is understanding other\'s code.

For example, I am contractor, hired to rescue some project very quickly. F

Answer 1

The book Object-Oriented Reengineering Patterns deals with this in detail. Unfortunately there is no silver bullet attached :-)

However, it lists a lot of useful techniques for taking over legacy code. In brief

• interview at least some of the original developers (if they are still around) about
  • development history: phases, releases
  • current state of affairs
  • team social structure, politics, dynamics: when and why did people join and leave
  • bugs: typical, easiest, hardest
  • code quality: cleanest / ugliest parts
  • configuration data: form, content and usage
  • unit / integration / manual / ... test cases and data
  • SCM branch structure and usage
  • documentation: what is documented where, is it up to date
  • contact persons for external interfaces
• Watch developers / users during demo to find
  • main features
  • typical use cases
  • usage anecdotes
  • good / bad, missing / superfluous functionality
• "read all the code in one hour"
  • get high level view of class hierarchies, interfaces
  • take multiple sessions if needed
  • identify large structures (these often contain important functionality)
  • look for design patterns
  • check comments (they can reveal a lot, but may be also misleading)
• skim documentation (if there is any)
  • just record the availability of specific types of docs e.g. specification, UML diagram, Wiki, Javadoc etc.
  • is it useful and why (not)
  • is it up to date