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ISBN-13: 978-0-13-468599-1 ISBN-10: 0-13-468599-7 1 17 To my family: Cindy, Tim, and Matt Contents Foreword Preface Acknowledgments 1 Introduction 2 Creating and Destroying Objects 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 Item 4: Enforce noninstantiability with a private constructor Item 5: Prefer dependency injection to hardwiring resources Item 6: Avoid creating unnecessary objects Item 7: Eliminate obsolete object references Item 8: Avoid finalizers and cleaners Item 9: Prefer try-with-resources to try-finally 3 Methods Common to All Objects Item 10: Obey the general contract when overriding equals Item 11: Always override hashCode when you override equals Item 12: Always override toString Item 13: Override clone judiciously Item 14: Consider implementing Comparable 4 Classes and Interfaces Item 15: Minimize the accessibility of classes and members Item 16: In public classes, use accessor methods, not public fields Item 17: Minimize mutability Item 18: Favor composition over inheritance Item 19: Design and document for inheritance or else prohibit it Item 20: Prefer interfaces to abstract classes Item 21: Design interfaces for posterity Item 22: Use interfaces only to define types Item 23: Prefer class hierarchies to tagged classes Item 24: Favor static member classes over nonstatic Item 25: Limit source files to a single top-level class 5 Generics Item 26: Don’t use raw types Item 27: Eliminate unchecked warnings Item 28: Prefer lists to arrays Item 29: Favor generic types Item 30: Favor generic methods Item 31: Use bounded wildcards to increase API flexibility Item 32: Combine generics and varargs judiciously Item 33: Consider typesafe heterogeneous containers 6 Enums and Annotations Item 34: Use enums instead of int constants Item 35: Use instance fields instead of ordinals Item 36: Use EnumSet instead of bit fields Item 37: Use EnumMap instead of ordinal indexing Item 38: Emulate extensible enums with interfaces Item 39: Prefer annotations to naming patterns Item 40: Consistently use the Override annotation Item 41: Use marker interfaces to define types 7 Lambdas and Streams Item 42: Prefer lambdas to anonymous classes Item 43: Prefer method references to lambdas Item 44: Favor the use of standard functional interfaces Item 45: Use streams judiciously Item 46: Prefer side-effect-free functions in streams Item 47: Prefer Collection to Stream as a return type Item 48: Use caution when making streams parallel 8 Methods Item 49: Check parameters for validity Item 50: Make defensive copies when needed Item 51: Design method signatures carefully Item 52: Use overloading judiciously Item 53: Use varargs judiciously Item 54: Return empty collections or arrays, not nulls Item 55: Return optionals judiciously Item 56: Write doc comments for all exposed API elements 9 General Programming Item 57: Minimize the scope of local variables Item 58: Prefer for-each loops to traditional for loops Item 59: Know and use the libraries Item 60: Avoid float and double if exact answers are required Item 61: Prefer primitive types to boxed primitives Item 62: Avoid strings where other types are more appropriate Item 63: Beware the performance of string concatenation Item 64: Refer to objects by their interfaces Item 65: Prefer interfaces to reflection Item 66: Use native methods judiciously Item 67: Optimize judiciously Item 68: Adhere to generally accepted naming conventions 10 Exceptions Item 69: Use exceptions only for exceptional conditions Item 70: Use checked exceptions for recoverable conditions and runtime exceptions for programming errors Item 71: Avoid unnecessary use of checked exceptions Item 72: Favor the use of standard exceptions Item 73: Throw exceptions appropriate to the abstraction Item 74: Document all exceptions thrown by each method Item 75: Include failure-capture information in detail messages Item 76: Strive for failure atomicity Item 77: Don’t ignore exceptions 11 Concurrency Item 78: Synchronize access to shared mutable data Item 79: Avoid excessive synchronization Item 80: Prefer executors, tasks, and streams to threads Item 81: Prefer concurrency utilities to wait and notify Item 82: Document thread safety Item 83: Use lazy initialization judiciously Item 84: Don’t depend on the thread scheduler 12 Serialization Item 85: Prefer alternatives to Java serialization Item 86: Implement Serializable with great caution Item 87: Consider using a custom serialized form Item 88: Write readObject methods defensively Item 89: For instance control, prefer enum types to readResolve Item 90: Consider serialization proxies instead of serialized instances Items Corresponding to Second Edition References Index