Java has changed dramatically since the previous edition of Effective Java was published shortly after the release of Java 6. This Jolt award-winning classic has now been thoroughly updated to take full advantage of the latest language and library features. The support in modern Java for multiple paradigms increases the need for specific best-practices advice, and this book delivers.

As in previous editions, each chapter of Effective Java, Third Edition, consists of several “items,” each presented in the form of a short, stand-alone essay that provides specific advice, insight into Java platform subtleties, and updated code examples. The comprehensive descriptions and explanations for each item illuminate what to do, what not to do, and why.

The third edition covers language and library features added in Java 7, 8, and 9, including the functional programming constructs that were added to its object-oriented roots. Many new items have been added, including a chapter devoted to lambdas and streams.

New coverage includes

• Functional interfaces, lambda expressions, method references, and streams
• Default and static methods in interfaces
• Type inference, including the diamond operator for generic types
• The @SafeVarargs annotation
• The try-with-resources statement
• New library features such as the Optional interface, java.time, and the convenience factory methods for collections

Foreword xi

Chapter 1: Introduction 1

Chapter 2: Creating and Destroying Objects 5

Item 1: Consider static factory methods instead of constructors 5

Item 2: Consider a builder when faced with many constructor parameters 10

Item 3: Enforce the singleton property with a private constructor or an enum type 17

Item 4: Enforce noninstantiability with a private constructor 19

Item 5: Prefer dependency injection to hardwiring resources 20

Item 6: Avoid creating unnecessary objects 22

Item 7: Eliminate obsolete object references 26

Item 8: Avoid finalizers and cleaners 29

Item 9: Prefer try-with-resources to try-finally 34

Chapter 3: Methods Common to All Objects 37

Item 10: Obey the general contract when overriding equals 37

Item 11: Always override hashCode when you override equals 50

Item 12: Always override toString 55

Item 13: Override clone judiciously 58

Item 14: Consider implementing Comparable 66

Chapter 4: Classes and Interfaces 73

Item 15: Minimize the accessibility of classes and members 73

Item 16: In public classes, use accessor methods, not public fields 78

Item 17: Minimize mutability 80

Item 18: Favor composition over inheritance 87

Item 19: Design and document for inheritance or else prohibit it 93

Item 20: Prefer interfaces to abstract classes 99

Item 21: Design interfaces for posterity 104

Item 22: Use interfaces only to define types 107

Item 23: Prefer class hierarchies to tagged classes 109

Item 24: Favor static member classes over nonstatic 112

Item 25: Limit source files to a single top-level class 115

Chapter 5: Generics 117

Item 26: Don’t use raw types 117

Item 27: Eliminate unchecked warnings 123

Item 28: Prefer lists to arrays 126

Item 29: Favor generic types 130

Item 30: Favor generic methods 135

Item 31: Use bounded wildcards to increase API flexibility 139

Item 32: Combine generics and varargs judiciously 146

Item 33: Consider typesafe heterogeneous containers 151

Chapter 6: Enums and Annotations 157

Item 34: Use enums instead of int constants 157

Item 35: Use instance fields instead of ordinals 168

Item 36: Use EnumSet instead of bit fields 169

Item 37: Use EnumMap instead of ordinal indexing 171

Item 38: Emulate extensible enums with interfaces 176

Item 39: Prefer annotations to naming patterns 180

Item 40: Consistently use the Override annotation 188

Item 41: Use marker interfaces to define types 191

Chapter 7: Lambdas and Streams 193

Item 42: Prefer lambdas to anonymous classes 193

Item 43: Prefer method references to lambdas 197

Item 44: Favor the use of standard functional interfaces 199

Item 45: Use streams judiciously 203

Item 46: Prefer side-effect-free functions in streams 210

Item 47: Prefer Collection to Stream as a return type 216

Item 48: Use caution when making streams parallel 222

Chapter 8: Methods 227

Item 49: Check parameters for validity 227

Item 50: Make defensive copies when needed 231

Item 51: Design method signatures carefully 236

Item 52: Use overloading judiciously 238

Item 53: Use varargs judiciously 245

Item 54: Return empty collections or arrays, not nulls 247

Item 55: Return optionals judiciously 249

Item 56: Write doc comments for all exposed API elements 254

Chapter 9: General Programming 261

Item 57: Minimize the scope of local variables 261

Item 58: Prefer for-each loops to traditional for loops 264

Item 59: Know and use the libraries 267

Item 60: Avoid float and double if exact answers are required 270

Item 61: Prefer primitive types to boxed primitives 273

Item 62: Avoid strings where other types are more appropriate 276

Item 63: Beware the performance of string concatenation 279

Item 64: Refer to objects by their interfaces 280

Item 65: Prefer interfaces to reflection 282

Item 66: Use native methods judiciously 285

Item 67: Optimize judiciously 286

Item 68: Adhere to generally accepted naming conventions 289

Chapter 10: Exceptions 293

Item 69: Use exceptions only for exceptional conditions 293

Item 70: Use checked exceptions for recoverable conditions and runtime exceptions for programming errors 296

Item 71: Avoid unnecessary use of checked exceptions 298

Item 72: Favor the use of standard exceptions 300

Item 73: Throw exceptions appropriate to the abstraction 302

Item 74: Document all exceptions thrown by each method 304

Item 75: Include failure-capture information in detail messages 306

Item 76: Strive for failure atomicity 308

Item 77: Don’t ignore exceptions 310

Chapter 11: Concurrency 311

Item 78: Synchronize access to shared mutable data 311

Item 79: Avoid excessive synchronization 317

Item 80: Prefer executors, tasks, and streams to threads 323

Item 81: Prefer concurrency utilities to wait and notify 325

Item 82: Document thread safety 330

Item 83: Use lazy initialization judiciously 333

Item 84: Don’t depend on the thread scheduler 336

Chapter 12: Serialization 339

Item 85: Prefer alternatives to Java serialization 339

Item 86: Implement Serializable with great caution 343

Item 87: Consider using a custom serialized form 346

Item 88: Write readObject methods defensively 353

Item 89: For instance control, prefer enum types to readResolve 359

Item 90: Consider serialization proxies instead of serialized instances 363