You are previewing Effective Java, 2nd Edition.

Effective Java, 2nd Edition

Cover of Effective Java, 2nd Edition by Joshua Bloch Published by Addison-Wesley Professional
  1. Copyright
    1. Dedication
  2. Praise for the First Edition
  3. The Java™ Series
  4. Foreword
  5. Preface
    1. Preface to the Second Edition
    2. Preface to the First Edition
  6. Acknowledgments
    1. Acknowledgments for the Second Edition
    2. Acknowledgments for the First Edition
  7. 1. Introduction
  8. 2. Creating and Destroying Objects
    1. Item 1: Consider static factory methods instead of constructors
    2. Item 2: Consider a builder when faced with many constructor parameters
    3. Item 3: Enforce the singleton property with a private constructor or an enum type
    4. Item 4: Enforce noninstantiability with a private constructor
    5. Item 5: Avoid creating unnecessary objects
    6. Item 6: Eliminate obsolete object references
    7. Item 7: Avoid finalizers
  9. 3. Methods Common to All Objects
    1. Item 8: Obey the general contract when overriding equals
    2. Item 9: Always override hashCode when you override equals
    3. Item 10: Always override toString
    4. Item 11: Override clone judiciously
    5. Item 12: Consider implementing Comparable
  10. 4. Classes and Interfaces
    1. Item 13: Minimize the accessibility of classes and members
    2. Item 14: In public classes, use accessor methods, not public fields
    3. Item 15: Minimize mutability
    4. Item 16: Favor composition over inheritance
    5. Item 17: Design and document for inheritance or else prohibit it
    6. Item 18: Prefer interfaces to abstract classes
    7. Item 19: Use interfaces only to define types
    8. Item 20: Prefer class hierarchies to tagged classes
    9. Item 21: Use function objects to represent strategies
    10. Item 22: Favor static member classes over nonstatic
  11. 5. Generics
    1. Item 23: Don’t use raw types in new code
    2. Item 24: Eliminate unchecked warnings
    3. Item 25: Prefer lists to arrays
    4. Item 26: Favor generic types
    5. Item 27: Favor generic methods
    6. Item 28: Use bounded wildcards to increase API flexibility
    7. Item 29: Consider typesafe heterogeneous containers
  12. 6. Enums and Annotations
    1. Item 30: Use enums instead of int constants
    2. Item 31: Use instance fields instead of ordinals
    3. Item 32: Use EnumSet instead of bit fields
    4. Item 33: Use EnumMap instead of ordinal indexing
    5. Item 34: Emulate extensible enums with interfaces
    6. Item 35: Prefer annotations to naming patterns
    7. Item 36: Consistently use the Override annotation
    8. Item 37: Use marker interfaces to define types
  13. 7. Methods
    1. Item 38: Check parameters for validity
    2. Item 39: Make defensive copies when needed
    3. Item 40: Design method signatures carefully
    4. Item 41: Use overloading judiciously
    5. Item 42: Use varargs judiciously
    6. Item 43: Return empty arrays or collections, not nulls
    7. Item 44: Write doc comments for all exposed API elements
  14. 8. General Programming
    1. Item 45: Minimize the scope of local variables
    2. Item 46: Prefer for-each loops to traditional for loops
    3. Item 47: Know and use the libraries
    4. Item 48: Avoid float and double if exact answers are required
    5. Item 49: Prefer primitive types to boxed primitives
    6. Item 50: Avoid strings where other types are more appropriate
    7. Item 51: Beware the performance of string concatenation
    8. Item 52: Refer to objects by their interfaces
    9. Item 53: Prefer interfaces to reflection
    10. Item 54: Use native methods judiciously
    11. Item 55: Optimize judiciously
    12. Item 56: Adhere to generally accepted naming conventions
  15. 9. Exceptions
    1. Item 57: Use exceptions only for exceptional conditions
    2. Item 58: Use checked exceptions for recoverable conditions and runtime exceptions for programming errors
    3. Item 59: Avoid unnecessary use of checked exceptions
    4. Item 60: Favor the use of standard exceptions
    5. Item 61: Throw exceptions appropriate to the abstraction
    6. Item 62: Document all exceptions thrown by each method
    7. Item 63: Include failure-capture information in detail messages
    8. Item 64: Strive for failure atomicity
    9. Item 65: Don’t ignore exceptions
  16. 10. Concurrency
    1. Item 66: Synchronize access to shared mutable data
    2. Item 67: Avoid excessive synchronization
    3. Item 68: Prefer executors and tasks to threads
    4. Item 69: Prefer concurrency utilities to wait and notify
    5. Item 70: Document thread safety
    6. Item 71: Use lazy initialization judiciously
    7. Item 72: Don’t depend on the thread scheduler
    8. Item 73: Avoid thread groups
  17. 11. Serialization
    1. Item 74: Implement Serializable judiciously
    2. Item 75: Consider using a custom serialized form
    3. Item 76: Write readObject methods defensively
    4. Item 77: For instance control, prefer enum types to readResolve
    5. Item 78: Consider serialization proxies instead of serialized instances
  18. Items Corresponding to First Edition
  19. References
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Chapter 2. Creating and Destroying Objects

This chapter concerns creating and destroying objects: when and how to create them, when and how to avoid creating them, how to ensure they are destroyed in a timely manner, and how to manage any cleanup actions that must precede their destruction.

Item 1: Consider static factory methods instead of constructors

The normal way for a class to allow a client to obtain an instance of itself is to provide a public constructor. There is another technique that should be a part of every programmer’s toolkit. A class can provide a public static factory method, which is simply a static method that returns an instance of the class. Here’s a simple example from Boolean (the boxed primitive class for the primitive type ...

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