Conference Notes #

Day 1 #

9:00 Keynote - The Long Road @sandromancuso #

“Recruiters are a disease that need to be irradicated”

Jobs specs to weed out the worst NOT to get the best

10:30 RxJava #

MVP: mosby/nucleus

11:30 Gradle Perf (Gradle dev vp) #

• Single src of truth
• Ide-> tooling api > gradle
• –rerun-tasks (runs uptodate tasks again)
• Gradle test -t (contnious mode)
• Task.mustrunafter taskB
• Realease 2.9 gradle wil be much faster. (+40% bigger projects)
• Config Phase: android plugin is black box for gradle hence no optimization possible by gradle
• Exp android plugin:
• Feat.: New software model (service/clien)
• Mooc: udacity free android gradle course

11:30 Reverse Engineering #

aapt dump strings ….apk -> returns all strings inside app

Basic tools:

• dex2jar (bad quality)
• apktool
• androguard (python based, collection of tools)
• Santoku (bootable lubuntu based linux env)
• Radare2
• Ida pro (disassembla)
• Jeb2 (Dalvik -> java decompiler)
• CodeInspect

Security:

Proguard, dexguard, sqlcipher

androguard: python androlyze.py -s -> interactive console to analyse eg. permission usage

Books

12:30 Gradle Plugins #

• Boring

14:30 Gradle Android Perf tips #

Config Phase

• Test overhead with –dry-run also –profile
• –configure-ondemand skips unneded overhead (also in AS)
• –daemon (extra process) faster builds
• Use 2.8 gradle + Use 1.8 jdk (ie current vesions)
• Avoid heavy scripting
• Dont use + in dep or –offline

Execution Phase

• Skip dynamic var in builconfig, use resValue instead ( res change is faster than java)
• Use minsdk 21 + multidex true saves merge phase
• Large Project: faster when multiple modules
• –parallel (experimental) needs decoupled proj
• Incremental javac but does not work yet in android
• Alternative buck, bazel, pants

15:15 Adv. Concurrency #

• Weakhashmap dont use literal string && boxed primitive
• Refernce Api, refernce queue
• Avoid finalizer use phantom ref + ref queue
• LeakCanary lib detects leaks in app
• Prefer Runtime.get().gc()
• IdentityHashmap uses == instead of equals
• PendingIntent, messenger, resultreveiver
• Dont use Eventbus for everything (CyclicBarrier
• CyclicBarrier

15:15 Animate me - if you dont do it for me, do it for chet #

• Basic Drawable Animations
• Interpollators, Drawable Animations
• Vector Animations: Animate parts and paths
• CoordinatorLayout
• Boring

Patrick must see basecamp talks #

• Gradle performance
• Genymode +CI
• Adv. Concurrency
• Animations tips and tricks

Florian

• Animations
• Gradle

Day 2 #

9:00 Keynote - Android for Java Devs (Haase) #

• Read medium 10 articles “Developing for Android” @chethaase
• Memory == Perf
• GC_FOR_ALLOC avoid!
• Fewer Alloc = faster
• Avoid alloc in anim, could cause gc (alloc tracker: start anim then alloc tracker, should not alloc stuff)
• Object pools may be good in Android
• Array better than list when fixed size
• Mutalbility saves allocs
• Foreach allocs iterator even if empty ( in indraw eg)
• Avoid slow static init
• Systrace show whats going on ( better in marshmallow)
• Hardware layer updates (texture during anim, if view hirachy changed)

10:00 Jack & Jill (Eric lafortune) #

• Jack already used to build aosp sdk
• Xml > aapt to binary
• Jack Src to dex
• Jill class to .jayce
• Jack includes minification
• Htfz build time similar like old compiler
• Optimization on compiler bytecode lvl makes a difference
• Jack will probably support java 1.8 but lambdas maybe only syntacticalsugar

11:00 ORMs #

• Kevin (presenter) wrote ormlite
• GreenDao actually not faster
• Android getting mature
• Realm good but not production ready (query on main thread)
• Src gen slightly faster than reflections
• Dbflow src gen type usually fastest
• SugarORm seems to be the worst

11:00 Android Wear #

• Marshmallow: values-round
• More Views
• Ambient mode: setAmbientEnabled only dims display. Only use callback onUpdate
• Cache all the data
• Publish: same package name, version number, key
• Permissions need to be granted before first run
• Moto360 bad for development (takes too long to deploy)

12:00 Scrolling techniques (cyril mottier) #

• Complex hirachy for scrollable types
• Listview scroll listener does not give correct y values
• OnTouchEvent velocity tracker.obtain()
• Nested scroll types: one for a axis, bezel scrolling, boundary scrolling ( View.canScrollHorizontally),
• nested scroll supported nativly on sdk21+ for scrillview, listview, etc
• Intercepeters

13:45 Power optimization #

• Display uses 45% power, network 30%, cpu 9%
• Batching network: alarmManager.setInexactRepeating, SyncAdapter, jobscheduler
• Persisting connection better than polling
• AT&T Application Resource Manager
• Test battery: battery historian 1.0 & 2.0 (phyton script creates report)

13:45 Building Meaningful Motion (Nick Butcher) #

• Again basic animations…
• Toolbar can be excluded from the activity transitions
• animated-selector
• Choreographer

14:45 Advanced Development with Kotlin (Jake Wharton) #

• Why new lang? Lang restrictions (util, nullability, verbose), android api (inheritance party, null everywhere)
• Extension Functions rock! (Add func to existing class)
• High order functions possible, also in combination with ext func
• Func as param will not have ref to outer class
• Ext func expressapis fix bad apis
• Kotlin has view extension
• First beta now; going to 1.0 soon
• No official google support in sight

15:45 Vector Graphics in Android #

• VectorDrawable partially supports svg (only pathdata)
• VectorDrawableCompat in future?
• Can be animated (group)
• Clip path clips pathdata
• AnimatedVectorDrawable
• TrimPathEnd draws percentage of path to animate to look like it gets drawn
• Objectanimator can animate pathdata (very powerful); must have same number of cmds and cmd types; can transition from eg. Square to triangle
• Convert vector to png does not support groups
• Stylingandroid.com find the presentation which is a live app (open sourced) with all the example vector drawables

15:45 Infer - Static Analysis Tool by facebook #

• Bugs, bugs and bugs
• For java, c, objective c
• Checks incremental changes, deep analysis
• Facebook uses linter & infer
• Supports gradle, buck, maven, ant
• 3 phases: capture, analyze, report
• Capture: creates all possible control flow path
• Analyze: pre/post conditions
• Report: CI
• fbinfer.com / infer –incremental – gradle build
• Can detect nullpointers, resource leaks (cursor, streams, sockets), acitivty leaks
• Comming soon: context leaks, array bounds, data flow
• No AndroidStudio plugin -> CI