Android

A JPEG file can have Exif metadata which can provide the rotation/translation field information for a raw JPEG image. So, a landscape raw JPEG image could actually be a portrait because it’s EXIF orientation could be set to ORIENTATION_ROTATE_90, the best way to handle such scenarios is to either use a library like Picasso or Glide or at least learn from them. Here is a piece of code from Picasso which loads a JPEG as an in-memory bitmap and performs the right translation/rotation....

I installed Android Studio via homebrew “brew cask install android-studio” as a part of my automated Mac OS setup. Recently, Android Studio prompted me that an update is available. When I accepted to update, it failed with an error “Studio does not have write access to /private/var/folders/wt/rjv6_wcn4f97_2nth7fqftqh0000gn/T/AppTranslocation/19A80F28-865B-41FC-AA87-B8E43C826FCB/d/Android Studio.app/Contents. Please run it by a privileged user to update.” This error was confusing; I was running Android Studio as myself, a nonprivileged user and the same user owned this directory....

All languages have certain semantics for dealing with error cases. C deals with them by setting error codes. Java deals with them by throwing exceptions. JavaScript deals with them by throwing exceptions as well but unlike Java, it does have any concept of checked Exceptions. The JS interpreter just stops. And this has some interesting implications in hybrid scenarios like a Webview based app. Consider a simple Android app where most of the code is in JavaScript but is making a request to Java layer....

The core idea behind resumable upload is straightforward if you are uploading a big file, then you are going to encounter users in the network conditions where they cannot upload the file in a single network session. The client-side code, to avoid restarting the file upload from the beginning, must figure out what portion of the file was uploaded and “resume” the upload of the rest. How to do resumable upload Before starting the upload, send a unique ID generated from the file contents to the server like MD-5 or SHA-256....

This is a long post. It covers several decisions like API version, distribution beyond play store, UI & network performance, and minimizing RAM, disk, and battery usage.

Android development requires tons of disconnected approaches for development and testing. Consider some scenarios To test runtime permission - Go to Settings -> Applications -> Application info of the app you are looking for and disable that permission. To test a fresh install - adb shell pm clear-data com.example To test your app under the battery-saver mode - turn on the battery saver mode by expanding the notification bar To stop the execution of an app - kill it via activity manager, adb shell am kill com....

Highlights All android support library code is moving to the androidx namespace. No more android.support.v4 or android. support.v7 namespaces. Android app bundle to split the app into downloadable modules Navigation library to set up navigation between different activities/fragments. Use WorkManager for background work - this is an improvement to JobScheduler Major improvements to Android Studio. Most standalone tools were deprecated in favor of adding the same functionality into Android Studio. Major improvements to Android Vitals which in Google Play to learn more about what’s going on with the Android app’s performance....

Let’s say you are developing an Android app com.example.android and want to access its database file named “content” from the test device/emulator. To access this file, located in app’s database directory, on both rooted and unrooted device would be Bash 1 2 3 4 5 $ APP_NAME=com.example.android $ adb shell run-as $APP_NAME cp databases/content.db /sdcard/content.db && $ adb pull /sdcard/content.db content.db && $ adb shell rm /sdcard/content.db ... This seems to work but is incorrect....

Infrastructure - Architecture & Performance Android Vitals - More visibility in Google Play dev console on battery drain, wakelocks being held for too long, ANRs, crashes, dropped frames, and frozen frames. Architecture components - better handling of the lifecycle, Room (ORM for Sqlite), live data observers. The API looks clunky though. Performance 50% 1-star reviews mention stability & bugs. 60% 5-star reviews mention speed, design, or reliability. Apps with > 5% crash rate have 30% higher uninstall rate....

Almost everyone developing an Android app has seen something like this in their device logs. Bash 1 I/Choreographer(1200): Skipped 60 frames! The application may be doing too much work on its main thread. On most devices, the Android platform tries to render a new frame every 16 milliseconds (60 fps). The rendering requires that whatever work is happening on the UI thread should finish in that timeframe (well, actually in less than that)....