Library Developer Confidential

Slide 1

Slide 1 text

Elliott Chenger @echenger Library Developer Conﬁdential

Slide 2

Slide 2 text

No content

Slide 3

Slide 3 text

Wall-E Artoo

Slide 4

Slide 4 text

AAR == Android Archive

Slide 5

Slide 5 text

AAR == Android Archive Just a fancy zip

Slide 6

Slide 6 text

Anatomy of an AAR classes.jar AndroidManifest.xml Res R.txt Public.txt

Slide 7

Slide 7 text

Anatomy of an AAR assets JNI Lib JARs Proguard.txt lint.jar

Slide 8

Slide 8 text

Why should you build a library?

Slide 9

Slide 9 text

Faster builds Architecture and Portability Android App Bundles and Instant Apps

Slide 10

Slide 10 text

Speed

Slide 11

Slide 11 text

App

Slide 12

Slide 12 text

class Pug { companion object { val isHungry = true } }

Slide 13

Slide 13 text

class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } }

Slide 14

Slide 14 text

:app 14s

Slide 15

Slide 15 text

class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val textView = findViewById(R.id.text_view) textView.text = "Pugs are always hungry ${Pug.isHungry}" } }

Slide 16

Slide 16 text

:app 14s

Slide 17

Slide 17 text

App

Slide 18

Slide 18 text

App Lib

Slide 19

Slide 19 text

class Pug { companion object { val isHungry = true } }

Slide 20

Slide 20 text

class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } }

Slide 21

Slide 21 text

:app 7s :pugs 7s

Slide 22

Slide 22 text

–Library Skeptic “Nothing changed!”

Slide 23

Slide 23 text

Slide 24

Slide 24 text

:app 7s :pugs UP-TO-DATE

Slide 25

Slide 25 text

:app 7s :pugs UP-TO-DATE

Slide 26

Slide 26 text

Build Caching Added 3.5

Slide 27

Slide 27 text

Build Caching Added 3.5 Support for Build Caching Added 3.0.0

Slide 28

Slide 28 text

- Gradle Documentation “The best way to do work faster is to not do work that doesn’t need doing.”

Slide 29

Slide 29 text

No content

Slide 30

Slide 30 text

Feature Based Architecture

Slide 31

Slide 31 text

App

Slide 32

Slide 32 text

App Feat. A Feat. B

Slide 33

Slide 33 text

Removing features is easier

Slide 34

Slide 34 text

App Feat. A Feat. B

Slide 35

Slide 35 text

App Feat. A

Slide 36

Slide 36 text

dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" implementation 'com.android.support:appcompat-v7:27.1.1' implementation project(':pugs') implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }

Slide 37

Slide 37 text

Slide 38

Slide 38 text

Slide 39

Slide 39 text

dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" implementation 'com.android.support:appcompat-v7:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }

Slide 40

Slide 40 text

Sharing features

Slide 41

Slide 41 text

App 1 Feat. A App 2

Slide 42

Slide 42 text

Android App Bundles and Instant Apps

Slide 43

Slide 43 text

App

Slide 44

Slide 44 text

App Feature A Instant App

Slide 45

Slide 45 text

App Feature A Instant App

Slide 46

Slide 46 text

App Feature A Instant App Util Lib

Slide 47

Slide 47 text

Project Setup

Slide 48

Slide 48 text

Single Project

Slide 49

Slide 49 text

Only deploys in one app? Does it need to be shared with others?

Slide 50

Slide 50 text

Only deploys in one app? Yes Does it need to be shared with others? No

Slide 51

Slide 51 text

App Lib Single Project

Slide 52

Slide 52 text

No content

Slide 53

Slide 53 text

No content

Slide 54

Slide 54 text

No content

Slide 55

Slide 55 text

No content

Slide 56

Slide 56 text

Settings.gradle include ':app', ':pugs'

Slide 57

Slide 57 text

Build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' implementation 'com.android.support:support-annotations:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' implementation project(":pugs") testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core: 3.0.2' }

Slide 58

Slide 58 text

Slide 59

Slide 59 text

Multi-Project

Slide 60

Slide 60 text

Only deploys in one app? Does it need to be shared with others?

Slide 61

Slide 61 text

Only deploys in one app? No Does it need to be shared with others? Yes

Slide 62

Slide 62 text

App Lib Multi-Project

Slide 63

Slide 63 text

App Lib Multi-Project Test App

Slide 64

Slide 64 text

App Lib Multi-Project Test App

Slide 65

Slide 65 text

AAR in a Libs Directory Library.aar

Slide 66

Slide 66 text

dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" implementation 'com.android.support:appcompat-v7:27.1.1' implementation files('libs/pugs-debug.aar') implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }

Slide 67

Slide 67 text

dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" implementation 'com.android.support:appcompat-v7:27.1.1' implementation files('libs/pugs-debug.aar') implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }

Slide 68

Slide 68 text

Slide 69

Slide 69 text

AAR in a Libs Directory repositories{ flatDir { dirs '../libs' } mavenCentral() }

Slide 70

Slide 70 text

AAR in a Libs Directory dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' implementation 'com.android.support:support-annotations:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' //Including a local gradle module implementation project(":pugs") //Including a local aar implementation(name:'beers-debug', ext:'aar') implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" }

Slide 71

Slide 71 text

Slide 72

Slide 72 text

07-01 17:50:12.887 4565-4565/com.omitneedlesscode.myapplication E/AndroidRuntime: FATAL EXCEPTION: main Process: com.omitneedlesscode.myapplication, PID: 4565 java.lang.NoClassDefFoundError: Failed resolution of: Ltimber/log/Timber$DebugTree; at com.omitneedlesscode.beers.BeerApplication.onCreate(BeerApplication.kt:10) at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1118) at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5791) at android.app.ActivityThread.-wrap1(Unknown Source:0) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1661) at android.os.Handler.dispatchMessage(Handler.java:105) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6541) at java.lang.reﬂect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Slide 73

Slide 73 text

Slide 74

Slide 74 text

public final fun getBreweries():kotlin.collections.List { /* compiled code */ } Note: AARs don’t contain source

Slide 75

Slide 75 text

AAR in a Libs Directory Library.aar

Slide 76

Slide 76 text

AAR in a Libs Directory Library.aar + Copy of Dependencies

Slide 77

Slide 77 text

AAR in a Libs Directory dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' implementation 'com.android.support:support-annotations:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' //Including a local gradle module implementation project(":pugs") //Including a local aar implementation(name:'beers-debug', ext:’aar’) implementation 'com.jakewharton.timber:timber:4.7.1' implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" }

Slide 78

Slide 78 text

AAR in a Libs Directory dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' implementation 'com.android.support:support-annotations:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' //Including a local gradle module implementation project(":pugs") //Including a local aar implementation(name:'beers-debug', ext:’aar’) implementation 'com.jakewharton.timber:timber:4.7.1' implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" }

Slide 79

Slide 79 text

AAR in a Libs Directory •Easy to use •Quick to test changes •Copy over library dependencies •Project switching •GIT LFS or your repo size will balloon •Hard to debug Pros Cons

Slide 80

Slide 80 text

App Lib Gradle Composite Project Test App

Slide 81

Slide 81 text

App Lib Gradle Composite Project Test App Lib Test App

Slide 82

Slide 82 text

Settings.gradle include ':app' includeBuild('../Beers'){ dependencySubstitution{ substitute module('com.omitneedlesscode:beers') with project(':beers') } }

Slide 83

Slide 83 text

Note // Gradle Composite Builds won't work with local AARs implementation(name:'beers-debug', ext:'aar') // They do work with Maven Dependencies implementation 'com.omitneedlesscode:beers:1.0'

Slide 84

Slide 84 text

Note // Gradle Composite Builds won't work with local AARs implementation(name:'beers-debug', ext:'aar') // They do work with Maven Dependencies implementation 'com.omitneedlesscode:beers:1.0'

Slide 85

Slide 85 text

No content

Slide 86

Slide 86 text

No content

Slide 87

Slide 87 text

No content

Slide 88

Slide 88 text

•Doesn’t impact other developers •Can change code in both library and app •No major modiﬁcations to the library project gradle ﬁles •Easier to debug •Newer feature so there have been some small bugs •To turn off composite mode may need to re- import library project •Can’t use with provided aars in Lib Pros Cons Gradle Composite Project

Slide 89

Slide 89 text

What is a Maven Dependency?

Slide 90

Slide 90 text

–Maven Documentation “A repository in Maven is used to hold build artifacts and dependencies of varying types.”

Slide 91

Slide 91 text

–Maven Documentation “A repository in Maven is used to hold build artifacts and dependencies of varying types.”

Slide 92

Slide 92 text

Library.aar + pom.xml

Slide 93

Slide 93 text

Maven Repo Library.aar + pom.xml

Slide 94

Slide 94 text

Maven Dependency Naming Convention :: 'com.omitneedlesscode:beers:1.0'

Slide 95

Slide 95 text

How do you create a Maven Dependency?

Slide 96

Slide 96 text

apply plugin: 'maven-publish'

Slide 97

Slide 97 text

publishing{ publications{ aar(MavenPublication){ groupId 'com.omitneedlesscode' artifactId 'beers' version = android.defaultConfig.versionName artifact new File('build/outputs/aar/beers-debug.aar') pom.withXml { def dependencies = asNode().appendNode('dependencies') configurations.implementation.allDependencies.each{ if(it.name!="unspecified"){ def dependency = dependencies.appendNode('dependency') dependency.appendNode('groupId', it.group) dependency.appendNode('artifactId', it.name) dependency.appendNode('version', it.version) } } } } } }

Slide 98

Slide 98 text

Slide 99

Slide 99 text

Slide 100

Slide 100 text

Slide 101

Slide 101 text

Slide 102

Slide 102 text

How do I test my maven dependency?

Slide 103

Slide 103 text

Maven Repo Library.aar + pom.xml

Slide 104

Slide 104 text

Maven Repo Library.aar + pom.xml Local

Slide 105

Slide 105 text

No content

Slide 106

Slide 106 text

11:06:46 PM: Executing task 'publishToMavenLocal'... Executing tasks: [publishToMavenLocal] Configuration on demand is an incubating feature. :beers:generatePomFileForAarPublication :beers:publishAarPublicationToMavenLocal :beers:publishToMavenLocal BUILD SUCCESSFUL in 5s 2 actionable tasks: 2 executed 11:06:51 PM: Task execution finished 'publishToMavenLocal'.

Slide 107

Slide 107 text

➜ ~ cd ~/.m2/

Slide 108

Slide 108 text

/Users//.m2/repository/com/omitneedlesscode/beers/1.0

Slide 109

Slide 109 text

➜ 1.0 ls beers-1.0.aar beers-1.0.pom

Slide 110

Slide 110 text

repositories{ flatDir { dirs '../libs' } mavenCentral() mavenLocal() }

Slide 111

Slide 111 text

repositories{ flatDir { dirs '../libs' } mavenCentral() mavenLocal() }

Slide 112

Slide 112 text

dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' implementation 'com.android.support:support-annotations:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' //Including a local gradle module implementation project(":pugs") //Including a local aar implementation ‘com.omitneedlesscode:beers:1.0' implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" }

Slide 113

Slide 113 text

dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' implementation 'com.android.support:support-annotations:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' //Including a local gradle module implementation project(":pugs") //Including a local aar implementation 'com.omitneedlesscode:beers:1.0' implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" }

Slide 114

Slide 114 text

Scripting

Slide 115

Slide 115 text

App Lib 1 build.gradle build.gradle

Slide 116

Slide 116 text

App Lib 1 build.gradle build.gradle Lib 2 build.gradle

Slide 117

Slide 117 text

App Lib 1 build.gradle build.gradle Lib 2 build.gradle … Lib N build.gradle

Slide 118

Slide 118 text

Shared Gradle Scripts

Slide 119

Slide 119 text

publishing{ publications{ aar(MavenPublication){ groupId 'com.omitneedlesscode' artifactId 'pugs' version = android.defaultConfig.versionName artifact new File('build/outputs/aar/pugs-debug.aar') pom.withXml { def dependencies = asNode().appendNode('dependencies') configurations.implementation.allDependencies.each{ if(it.name!="unspecified"){ def dependency = dependencies.appendNode('dependency') dependency.appendNode('groupId', it.group) dependency.appendNode('artifactId', it.name) dependency.appendNode('version', it.version) } } } } } }

Slide 120

Slide 120 text

Slide 121

Slide 121 text

Slide 122

Slide 122 text

Slide 123

Slide 123 text

artifact new File('build/outputs/aar/pugs-debug.aar') artifact new File('build/outputs/aar/beers-debug.aar') artifactId 'beers' artifactId 'pugs'

Slide 124

Slide 124 text

publish.gradle

Slide 125

Slide 125 text

apply plugin: 'maven-publish' ext.filePath = '' ext.expectedArtifactId = '' ext.expectedGroupId = '' ext.expectedVersion = '' publishing { publications { aar(MavenPublication) { groupId expectedGroupId artifactId expectedArtifactId version = expectedVersion artifact new File(filePath) pom.withXml { def dependencies = asNode().appendNode('dependencies') configurations.implementation.allDependencies.each { if (it.name != "unspecified") { def dependency = dependencies.appendNode('dependency') dependency.appendNode('groupId', it.group) dependency.appendNode('artifactId', it.name) dependency.appendNode('version', it.version) } } } } } }

Slide 126

Slide 126 text

ext.filePath = '' ext.expectedArtifactId = '' ext.expectedGroupId = '' ext.expectedVersion = ''

Slide 127

Slide 127 text

apply from: '../publish.gradle' ext.filePath = 'build/outputs/aar/cars-debug.aar' ext.expectedArtifactId = 'cars' ext.expectedGroupId = 'com.omitneedlesscode' ext.expectedVersion = app_version

Slide 128

Slide 128 text

Remote Shared Gradle Scripts

Slide 129

Slide 129 text

apply from: “https://foo.bar/publish.gradle” ext.filePath = 'build/outputs/aar/cars-debug.aar' ext.expectedArtifactId = 'cars' ext.expectedGroupId = 'com.omitneedlesscode' ext.expectedVersion = app_version

Slide 130

Slide 130 text

Slide 131

Slide 131 text

App Lib 1 build.gradle build.gradle Lib 2 build.gradle … Lib N build.gradle publish.gradle

Slide 132

Slide 132 text

./gradlew --profile --recompile-scripts --offline assembleDebug

Slide 133

Slide 133 text

Avoid Creating Dependency Hell

Slide 134

Slide 134 text

App Lib glide:3.8.0 glide:4.7.1

Slide 135

Slide 135 text

21:28:57.809 13647-13647/com.omitneedlesscode.nodependency E/AndroidRuntime: FATAL EXCEPTION: main Process: com.omitneedlesscode.nodependency, PID: 13647 java.lang.NoSuchMethodError: No virtual method load(Ljava/lang/String;)Lcom/bumptech/glide/ DrawableTypeRequest; in class Lcom/bumptech/glide/RequestManager; or its super classes (declaration of 'com.bumptech.glide.RequestManager' appears in /data/app/com.omitneedlesscode.nodependency-m1gfBVcawag- PWVRV_wyZQ==/split_lib_dependencies_apk.apk) at com.omitneedlesscode.pugs.PugActivity.onCreate(PugActivity.kt:16) at android.app.Activity.performCreate(Activity.java:6975) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892) at android.app.ActivityThread.-wrap11(Unknown Source:0) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593) at android.os.Handler.dispatchMessage(Handler.java:105) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6541) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Slide 136

Slide 136 text

Slide 137

Slide 137 text

App Lib glide:3.8.0 glide:4.7.1

Slide 138

Slide 138 text

Do you really need that library?

Slide 139

Slide 139 text

Yes

Slide 140

Slide 140 text

But do you need it in your library?

Slide 141

Slide 141 text

Not necessarily

Slide 142

Slide 142 text

Command Pattern

Slide 143

Slide 143 text

Command Pattern Deferred Responsibility Pattern

Slide 144

Slide 144 text

Library interface AppUtilities { var imageFetcher: ImageFetcher }

Slide 145

Slide 145 text

Library interface ImageFetcher { fun loadImageInView(imageUrl: String, defaultImageResource: Int, view: ImageView) }

Slide 146

Slide 146 text

App class GlideImageFetcher: ImageFetcher { override fun loadImageInView(imageUrl: String, defaultImageResource: Int, view: ImageView) { GlideApp.with(view).load(imageUrl).placeholder(defaultImageResource).into(view) } }

Slide 147

Slide 147 text

App Lib glide:3.8.0 glide:4.7.1

Slide 148

Slide 148 text

Manifests

Slide 149

Slide 149 text

Content Providers

Slide 150

Slide 150 text

Slide 151

Slide 151 text

Slide 152

Slide 152 text

Providers have one authority

Slide 153

Slide 153 text

Android Manifest Placeholders

Slide 154

Slide 154 text

android { defaultConfig { manifestPlaceholders = [hostName:"www.example.com"] } ... }

Slide 155

Slide 155 text

Slide 156

Slide 156 text

Resources

Slide 157

Slide 157 text

Overriding IDs Lib App Artoo R2

Slide 158

Slide 158 text

Overriding IDs Lib App Artoo R2

Slide 159

Slide 159 text

Overriding IDs build variant build type product flavor main source set library dependencies

Slide 160

Slide 160 text

Overriding IDs build variant build type product flavor main source set library dependencies