بهینه‌سازی عملکرد برنامه‌های اندروید

Today's Android apps developers are often running into the need to refine, improve and optimize their apps performances. As more complex apps can be created, it is even more important for developers to deal with this critical issue. Android allows developers to write apps using Java, C or a combination of both with the Android SDK and the Android NDK. __Pro Android Apps Performance Optimization__ reveals how to fine-tune your Android apps, making them more stable and faster. In this book, you'll learn the following: * How to optimize your Java code with the SDK, but also how to write and optimize native code using advanced features of the Android NDK such as using ARM single instruction multiple data (SIMD) instructions (in C or assembly) * How to use multithreading in your application, how make best use of memory and how to maximize battery life * How to use to some OpenGL optimizations and to Renderscript, a new feature in Android 3.0 (Honeycomb) and expanded in Android 4.0 (Ice Cream Sandwich). After reading and using this book, you'll be a better coder and your apps will be better-coded. Better-performing apps mean better reviews and eventually, more money for you as the app developer or your indie shop. ## What you’ll learn ## Who this book is for Android developers already familiar with Java and Android SDK, who want to go one step further and learn how to maximize performance. ## Table of Contents GetFullPageImage 1 Binder1 2 front-matter 2 Title Page 2 Copyright Page 3 Contents at a Glance 4 Table of Contents 5 About the Author 9 About the Technical Reviewers 10 AcknowledgmentsI 11 Introduction 12 fulltext 14 Chapter 1 Optimizing Java Code 14 How Android Executes Your Code 15 Optimizing Fibonacci 17 From Recursive To Iterative 18 BigInteger 19 Caching Results 24 android.util.LruCache 25 API Levels 26 Fragmentation 29 Data Structures 30 Responsiveness 33 Lazy initializations 35 StrictMode 36 SQLite 38 SQLite Statements 38 Transactions 41 Queries 43 Summary 44 fulltext(1) 45 Chapter 2 Getting Started With the NDK 45 What Is In the NDK? 46 Mixing Java and C/C++ Code 49 Declaring the Native Method 49 Implementing the JNI Glue LayerJava uses 50 Creating the Makefiles 52 Implementing the Native Function 53 Compiling the Native Library 55 Loading the Native Library 55 Application.mk 56 Optimizing For (Almost) All Devices 58 Supporting All Devices 59 Android.mk 62 Performance Improvements With C/C++ 65 More About JNI 69 Strings 70 Accessing Fields or Methods 71 Native Activity 74 Building the Missing Library 76 Alternative 82 Summary 83 fulltext(2) 84 Chapter 3 Advanced NDK 84 Assembly 84 Greatest Common Divisor 85 Color Conversion 90 Parallel Computation of Average 93 ARM Instructions 98 ARM NEON 107 CPU Features 108 C Extensions 109 Built-in Functions 110 Vector Instructions 110 Tips 114 Inlining Functions 115 Unrolling Loops 115 Preloading Memory 116 LDM/STM Instead Of LDR/STD 117 Summary 118 fulltext(3) 119 Chapter 4 Using Memory Efficiently 119 A Word On Memory 119 Data Types 121 Comparing Values 123 Other Algorithms 125 Sorting Arrays 126 Defining Your Own Classes 127 Accessing Memory 128 The Cache’s Line Size 129 Laying Out Your Data 130 Garbage Collection 135 Memory Leaks 135 References 137 Strong References 137 Soft, Weak, and Phantom References 138 Garbage Collection 140 APIs 141 Low Memory 141 Summary 142 fulltext(4) 143 Chapter 5 Multithreading and Synchronization 143 Threads 144 AsyncTask 147 Handlers and Loopers 150 Handlers 150 Loopers 152 Data Types 153 Synchronized, Volatile, Memory Model 153 Concurrency 157 Multicore 158 Modifying Algorithm For Multicore 159 Using Concurrent Cache 162 Activity Lifecycle 164 Passing Information 166 Remembering State 168 Summary 171 fulltext(5) 172 Chapter 6 Benchmarking And Profiling 172 Measuring Time 172 System.nanoTime() 173 Debug.threadCpuTimeNanos() 174 Tracing 176 Debug.startMethodTracing() 176 Using the Traceview Tool 177 Traceview in DDMS 179 Native Tracing 181 Generating Trace File For Traceview 181 Logging 183 Summary 185 fulltext(6) 186 Chapter 7 Maximizing Battery Life 186 Batteries 186 Measuring Battery Usage 189 Disabling Broadcast Receivers 192 Disabling and Enabling the Broadcast Receiver 195 Networking 196 Background Data 197 Data Transfer 198 Location 200 Unregistering a Listener 202 Frequency of Updates 202 Multiple Providers 203 Filtering Providers 205 Last Known Location 207 Sensors 208 Graphics 209 Alarms 210 Scheduling Alarms 212 WakeLocks 213 Preventing Issues 214 Summary 215 fulltext(7) 216 Chapter 8 Graphics 216 Optimizing Layouts 216 RelativeLayout 218 Merging Layouts 222 Reusing Layouts 223 View Stubs 224 Layout Tools 226 Hierarchy Viewer 227 layoutopt 227 OpenGL ES 227 Extensions 228 Texture Compression 230 Other Texture Compression Formats 234 Manifest 234 Mipmaps 235 Multiple APKs 237 Shaders 237 Scene Complexity 238 Culling 238 Render Mode 238 Power Consumption 238 Summary 239 fulltext(8) 240 Chater 9 RenderScript 240 Overview 240 Hello World 242 Hello Rendering 245 Creating a Rendering Script 246 Creating a RenderScriptGL Context 247 Extending RSSurfaceView 248 Setting the Content View 248 Adding Variables to Script 249 HelloCompute 252 Allocations 253 rsForEach 254 Performance 257 Native RenderScript APIs 258 rs_types.rsh 259 rs_core.rsh 262 rs_cl.rsh 264 rs_math.rsh 268 rs_graphics.rsh 269 rs_time.rsh 270 rs_atomic.rsh 271 RenderScript vs. NDK 272 Summary 272 back-matter 273 Index 273 Annotation Today's Android apps developers are often running into the need to refine, improve and optimize their apps performances. As more complex apps can be created, it is even more important for developers to deal with this critical issue. Android allows developers to write apps using Java, C or a combination of both with the Android SDK and the Android NDK. Pro Android Apps PerformanceOptimizationreveals how to fine-tune your Android apps, making them more stable and faster. In this book, you'll learn the following:How to optimize your Java code with the SDK, but also how to write and optimize native code using advanced features of the Android NDK such as using ARM single instruction multiple data (SIMD) instructions (in C or assembly)Howto use multithreading in your application, how make best use of memory and how to maximize battery lifeHow to use to some OpenGL optimizations and to Renderscript, a new feature in Android 3.0 (Honeycomb) and expanded in Android 4.0 (Ice Cream Sandwich). After reading and using this book, you'll be a better coder and your apps will be better-coded. Better-performing apps meanbetter reviews and eventually, more money for you as the app developer or your indie shop. What youll learnHow to optimize your applications in JavaHow to optimize your applications using the NDKHow to best use memory to maximize performanceHow to maximize battery lifeHow and when to use multi-threadingHow to benchmark and profile your codeHow to optimize OpenGL code and use RenderscriptWho this book is forAndroid developers already familiar with Java and Android SDK, who want to go one step further and learn how to maximize performance. Table of ContentsOptimizing Java codeGetting started with the Android NDKUsing advanced NDK featuresUsing memory efficientlyMultithreading and synchronizationBenchmarking and profiling your applicationMaximizing battery lifeOpenGL optimizationsRenderscript