item12

Always override `toString`

The toString method is automatically invoked by printf, string concatenation, and debuggers, so it should be overriden even if you never call it explicitly.
The general contract for toString - the returned string should be:
1. concise
2. informative
3. easy to read
A good toString implementation makes your class
1. easier to use
2. easier to debug
Format specification?
- Specifying the format:
  - Pros
    - The string can serve as a "standard, unambiguous, human-readable representation of the object."
      - e.g. "111-222-3333" <-> PhoneNumber object with area code = 111, prefix = 222, line number = 3333
    - The availability of complementing static factories / constructors.
      - e.g. Integer.valueOf(String s)
    - Suit well with value classes, e.g. phone number, because of the reasons mentioned above.
  - Cons
    - Specifying the format and then changing it in the future will break code that depends on the format.
- Not specifying the format:
  - Pros
    - Flexibility to add information or improve the format.
  - Cons
    - The advantages of specifying the format, static factories, are lost.
Provide programmatic access to the information contained in the value returned by toString.
- i.e. provide getters for such fields.
- Why? else the information has to parsed instead of just accessed.