Core Java Volume II–Advanced Features Eleventh Edition This page intentionally left blank Core Java Volume II–Advanced Features Eleventh Edition Cay S. Horstmann Boston • Columbus • New York • San Francisco • Amsterdam • Cape Town Dubai • London • Madrid • Milan • Munich • Paris • Montreal • Toronto • Delhi • Mexico City São Paulo • Sydney • Hong Kong • Seoul • Singapore • Taipei • Tokyo The author and publisher have taken care in the preparation of this book, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of the use of the information or programs contained herein. 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ISBN-13: 978-0-13-516631-4 ISBN-10: 0-13-516631-4 1 19 Contents Preface ........................................................................................................... xv Acknowledgments ......................................................................................... xxi Chapter 1: Streams ........................................................................................ 1 1.1 From Iterating to Stream Operations ................................................. 2 1.2 Stream Creation ................................................................................... 5 1.3 The filter, map, and flatMap Methods ................................................... 11 1.4 Extracting Substreams and Combining Streams ............................. 12 1.5 Other Stream Transformations ......................................................... 14 1.6 Simple Reductions .............................................................................. 15 1.7 The Optional Type ............................................................................. 16 1.7.1 Getting an Optional Value .................................................. 17 1.7.2 Consuming an Optional Value ............................................ 17 1.7.3 Pipelining Optional Values .................................................. 18 1.7.4 How Not to Work with Optional Values ........................... 19 1.7.5 Creating Optional Values .................................................... 20 1.7.6 Composing Optional Value Functions with flatMap ........... 21 1.7.7 Turning an Optional into a Stream .................................... 22 1.8 Collecting Results ............................................................................... 25 1.9 Collecting into Maps .......................................................................... 30 1.10 Grouping and Partitioning ................................................................ 34 1.11 Downstream Collectors ..................................................................... 36 1.12 Reduction Operations ........................................................................ 41 1.13 Primitive Type Streams ..................................................................... 43 1.14 Parallel Streams .................................................................................. 48 Chapter 2: Input and Output ........................................................................ 55 2.1 Input/Output Streams ........................................................................ 56 2.1.1 Reading and Writing Bytes .................................................. 56 2.1.2 The Complete Stream Zoo ................................................. 59 v vi Contents 2.1.3 Combining Input/Output Stream Filters ............................ 63 2.1.4 Text Input and Output ......................................................... 68 2.1.5 How to Write Text Output .................................................. 68 2.1.6 How to Read Text Input ...................................................... 70 2.1.7 Saving Objects in Text Format ............................................ 72 2.1.8 Character Encodings ............................................................. 75 2.2 Reading and Writing Binary Data .................................................... 78 2.2.1 The DataInput and DataOutput interfaces ................................... 78 2.2.2 Random-Access Files ............................................................ 80 2.2.3 ZIP Archives .......................................................................... 85 2.3 Object Input/Output Streams and Serialization ............................. 88 2.3.1 Saving and Loading Serializable Objects ........................... 88 2.3.2 Understanding the Object Serialization File Format .................................................................................... 93 2.3.3 Modifying the Default Serialization Mechanism ............. 100 2.3.4 Serializing Singletons and Typesafe Enumerations ........ 102 2.3.5 Versioning ............................................................................ 103 2.3.6 Using Serialization for Cloning ......................................... 106 2.4 Working with Files ........................................................................... 109 2.4.1 Paths ..................................................................................... 109 2.4.2 Reading and Writing Files ................................................. 112 2.4.3 Creating Files and Directories ........................................... 113 2.4.4 Copying, Moving, and Deleting Files ............................... 114 2.4.5 Getting File Information ..................................................... 116 2.4.6 Visiting Directory Entries ................................................... 118 2.4.7 Using Directory Streams .................................................... 120 2.4.8 ZIP File Systems .................................................................. 123 2.5 Memory-Mapped Files ..................................................................... 124 2.5.1 Memory-Mapped File Performance .................................. 125 2.5.2 The Buffer Data Structure .................................................. 132 2.6 File Locking ....................................................................................... 134 2.7 Regular Expressions ......................................................................... 137 2.7.1 The Regular Expression Syntax ......................................... 137 2.7.2 Matching a String ............................................................... 142 2.7.3 Finding Multiple Matches .................................................. 145 Contents vii 2.7.4 Splitting along Delimiters .................................................