Effective Java 3/E summary chanpter 8 (Shorter version)

Chanpter 8 : General Programming

You can find the longer version of this summary here.

1. Minimize the scope of local variables
   • Declare a varaible when it is first used
   • Keep methods small and do only one function
2. Prefer for-each loops to traditional for loops
   • Avoid using for-each loops for Destructive filtering, transfroming, parallel iteration
3. Know and use the libraries
4. Avoid float and double if exact answers are required
   • Float and double are designed for scientific and engineering calculations. (Follows IEEE 754 floating point)
   • Use BigDecimal, int or long!
5. Prefer primitive types to boxed primitives
   • Null safe
   • Use ==
   • Performance
6. Avoid strings where other types are more appropriate
   • If you use String as a key, it is used globally and is vulnerable to security.
7. Beware the performance of string concatenation
   • String concatenation is O(n^2)
8. Refer to objects by their interfaces
   • Declare interface type as possible for params, return, var, field
9. Prefer interfaces to reflection
   • Reflection: Java code exists in static area as byte code, and constructor, method, and field can be accessed only with the name of the class.
     • No type checking
     • Code smell
     • 11 times slower
   • Use reflection only when creating it, and refer to it by an interface or a higher class.
10. Avoid using JNI (Java Native Interface)
11. Don’t optimize, do it when you need it through profiling.