Effective Java

Recently, I’ve re-read awesome java book Effective Java by Joshua Bloch. The book contains 78 independent items, discussing various aspects of programming in java. Something like mini-design patterns with emphasis on their pros and cons.

Few notes from each item as a refresher.

Item 1: Consider static factory methods instead of constructors

Item 2: Consider a builder when faced with many constructor parameters

Item 3: Enforce the singleton property with a private constructor or an enum type

Caution: Discussed singleton without lazy initialization

enum Singleton {

Item 4: Enforce noninstantiability with a private constructor

Item 5: Avoid creating unnecessary objects

Item 6: Eliminate obsolete object references

Item 7: Avoid finalizers

Item 8: Obey the general contract when overriding equals

Item 9: Always override hashCode when you override equals

Item 10: Always override toString

Item 11: Override clone judiciously

Item 12: Consider implementing Comparable

Item 13: Minimize the accessibility of classes and members

Item 14: In public classes, use accessor methods, not public fields

Item 15: Minimize mutability

Item 16: Favor composition over inheritance

Item 17: Design and document for inheritance or else prohibit it

Item 18: Prefer interfaces to abstract classes

Item 19: Use interfaces only to define types

Item 20: Prefer class hierarchies to tagged classes

Item 21: Use function objects to represent strategies

Item 22: Favor static member classes over nonstatic

Item 23: Don’t use raw types in new code

Item 24: Eliminate unchecked warnings

Item 25: Prefer lists to arrays

Item 26: Favor generic types

Item 27: Favor generic methods

Item 28: Use bounded wildcards to increase API flexibility

Item 29: Consider typesafe heterogeneous containers

public class Favorites {
  public <T> void putFavorite(Class<T> type, T instance);
  public <T> T getFavorite(Class<T> type);

Item 30: Use enums instead of int constants

Item 31: Use instance fields instead of ordinals

Item 32: Use EnumSet instead of bit fields

Item 33: Use EnumMap instead of ordinal indexing

Item 34: Emulate extensible enums with interfaces

Item 35: Prefer annotations to naming patterns

Item 36: Consistently use the Override annotation

Item 37: Use marker interfaces to define types

Item 38: Check parameters for validity

Item 39: Make defensive copies when needed

Item 40: Design method signatures carefully

Item 41: Use overloading judiciously

Item 42: Use varargs judiciously

Item 43: Return empty arrays or collections, not nulls

Item 44: Write doc comments for all exposed API elements

Item 45: Minimize the scope of local variables

Item 46: Prefer for-each loops to traditional for loops

Item 47: Know and use the libraries

Item 48: Avoid float and double if exact answers are required

Item 49: Prefer primitive types to boxed primitives

Item 50: Avoid strings where other types are more appropriate

Item 51: Beware the performance of string concatenation

Item 52: Refer to objects by their interfaces

Item 53: Prefer interfaces to reflection

Item 54: Use native methods judiciously

Item 55: Optimize judiciously

Item 56: Adhere to generally accepted naming conventions

Item 57: Use exceptions only for exceptional conditions

Item 58: Use checked exceptions for recoverable conditions and runtime exceptions for programming errors

Item 59: Avoid unnecessary use of checked exceptions

Item 60: Favor the use of standard exceptions

Item 61: Throw exceptions appropriate to the abstraction

try {
  // Use lower-level abstraction to do our bidding
} catch(LowerLevelException e) {
  throw new HigherLevelException();

Item 62: Document all exceptions thrown by each method

Item 63: Include failure-capture information in detail messages

Item 64: Strive for failure atomicity

Item 65: Don’t ignore exceptions

Item 66: Synchronize access to shared mutable data

Item 67: Avoid excessive synchronization

Item 68: Prefer executors and tasks to threads

Item 69: Prefer concurrency utilities to wait and notify

Item 70: Document thread safety

Item 71: Use lazy initialization judiciously

Item 72: Don’t depend on the thread scheduler

Item 73: Avoid thread groups

Item 74: Implement Serializable judiciously

Item 75: Consider using a custom serialized form

Item 76: Write readObject methods defensively

Item 77: For instance control, prefer enum types to readResolve

Item 78: Consider serialization proxies instead of serialized instances

mishadoff 07 August 2014
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