The Definitive Guide to Java Platform Best Practices-Updated for Java 7, 8, and 9

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

  Autorentext

  Joshua Bloch is a professor at Carnegie Mellon University. He was formerly the chief Java architect at Google, a distinguished engineer at Sun Microsystems, and a senior systems designer at Transarc. He led the design and implementation of numerous Java platform features, including the JDK 5.0 language enhancements and the Java Collections Framework. He holds a Ph.D. in computer science from Carnegie Mellon University and a B.S. in computer science from Columbia University.

  Inhalt

  Foreword xi

  Preface xiii

  Acknowledgments xvii

  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

  Items Corresponding to Second Edition 367

  References 371

  Index 377