Getting Started with Android Development

You can complete all the Android-version of the labs in this course on the Android emulator, you don’t need a physical device. The labs are backward compatible to Android 13 (Tiramisu) (API Level 33) as the minimum SDK. If your phone cannot run Android 13 or later, you’d have to test the labs on the emulator, in which case, double check that your development host has enough resources (compute power, memory capacity, disk space) to host the emulator.

Minimum requirements?

Unfortunately I don’t have a minimum required host spec. The emulator ran fine on the following spec for the student reporting it:

• AMD Ryzen 5 3600 6-core 3.6 GHz
• 16 GB RAM
• 1 TB HD
• Windows 10 Education

whereas students with the following spec had trouble running the emulator:

• Intel Core i5 8th-gen
• 16 GB RAM
• 512 GB HD
• Windows 11 Home

Languages

We will develop in Kotlin only, not Java. Google has switched to “Kotlin first” since Google I/O 2019 and Jetpack Compose requires Kotlin. For 3rd-party libraries and SDKs, Kotlin can co-exist seamlessly with Java. Android Studio automatically converts Java code pasted into a Kotlin file. You can also invoke Java to Kotlin conversion from Android Studio’s menu: Code > Convert Java File to Kotlin File.

The course does not support any cross-platform frameworks, including React Native and Flutter. All course projects must be built natively. If you are contemplating cross-platform mobile development, please consult our collection of articles on industry experiences with cross-platform solutions.

Developing Android app

We assume:

• you have a device running Android 13 (Tiramisu) (API level 33).
  check version

  To check your Android version, on your phone navigate to Settings > (scroll all the way down) About phone > Android version.

• you will develop only in Kotlin, not Java.
• you will need to do some XML scripting.
• you are using Android Studio Hedgehog
• your entire team should be on the same version of Android Studio and Android API level.

alternative IDEs

You can use a different IDE (such as VSCode or IntelliJ), though we’ll “support” only Android Studio.

Setting up Android Studio

Installation:

1. Download Android Studio. Install and launch.
2. On the Welcome screen, click Next.
3. On the Install Type screen, choose Standard, click Next.
4. On the Select UI Theme screen, select your theme and click Next.
5. On the Verify Settings screen, click Next.
6. On the License Agreement screen, select the first group (android-sdk-license in the screenshot, may be different on your screen), click Accept (screenshot). It is ok to download materials for Platform 34.
7. Still on the License Agreement screen, select the second group (e.g., android-preview-license), click Accept (screenshot), if your License Agreement screen has a third and further groups, continue to select each and click Accept until the Finish button ungreys, click Finish (screenshot).
8. On the Downloading Components screen, wait until downloading is completed, the Finish button ungreys, then click Finish.
9. On the Welcome to Android Studio screen, choose More Actio... > SDK Manager (screenshot).

   Alternatively, choose Tools > SDK Manager once passed the Welcome screen.

10. On the Languages & Frameworks > Android SDK screen, check Android 13.0 (Tiramisu). You can uncheck Android API 34 if you are short of space, otherwise you can leave it checked. Do not click Apply nor OK yet.
11. Staying in the Languages & Frameworks > Android SDK screen, click on the SDK Tools tab and check Google Play Licensing Library (screenshot). Now click Apply.
12. On the Confirm Change screen, click OK.
13. On the SDK Component Installer screen, once installation is completed and the Finish button ungreys, click Finish.
14. On Android Studio [or File] > Preferences [or Settings]:

    On Windows, from Android Studio’s Welcome screen, navigate to Customize > All settings... (screenshot) or from the main menu File > Settings if past the Welcome screen.

    Navigate to Editor > General [drop down] > Auto Import, then in the Kotlin section near the bottom of the pane check Add unambiguous imports on the fly (screenshot). Do not check Optimize imports on the fly.

    With auto import enabled, as you enter code, Android Studio will automatically detect and determine which library you need to import. It will then prompt you to hit the Alt-Enter or Opt-Enter key combination to automatically import said library. Go ahead and import the suggested libraries.

    Sometimes, there are multiple library choices and Android Studio would have you choose. Most of the times the choice will be rather obvious (don’t choose the Audio library if you’re not implementing Audio, or do pick the one with the word compose if you’re using Jetpack Compose, for example). We will provide a full list of imports as an Appendix to each lab spec, so you can double check when in doubt. Or you could cut and paste all of the imports into your source files before any code. If you choose to cut-and-paste, be sure that you do NOT check Optimize imports on the fly, otherwise Android Studio will automatically remove them all for being unused and therefore unnecessary.

Missing essential plugins error

On Windows, if Android Studio would not launch and complains of Corrupted Installation and Missing essential plugins, delete the file C:\Users\%USERNAME%\AppData\Roaming\AndroidStudio*\disabled_plugins.txt [thanks C. Goh F22].

To run your app on your physical device, see the Running and debugging on device section below. To use the Android emulator, see the Running and debugging on an emulator section below.

About Android Studio

• Depending on the available resources of your development host, Android Studio can be slow doing the following:
  • Gradle syncing and project indexing
  • Gradle build can be especially SLOW (What is Gradle?)
  • Code may sometimes be underlined while correct as it takes time to refactor

  
  Source: reddit

• When references are unresolved for no good reason, try, in succession:

  Build > Clean Project
  Build > Rebuild Project
  File > Sync Project with Gradle Files
  File > Invalidate Caches/Restart...
  

• If Android Studio does unexpected things, e.g., Log.d() doesn’t print any debug messages, restart and see if malbehavior persists.

For Android Studio to run a little faster:

• Disable all non-essential plugins. We have only the following (in order of appearance) enabled:
  • Smali Support
  • Gradle
  • Groovy
  • Kotlin
  • Properties
  • JUnit
  • IntelliLang
  • Jetpack Compose
  • Toml
  • WebP Support
• Give it as much memory as you can afford: Android Studio [or File] > Settings [or Preferences] > Appearance & Behavior > System Settings > Memory Settings max out IDE and Daemon heap sizes

  Don’t forget to hit Apply before hitting OK for your changes to take.

Android Studio panes

• Left: Project directory, structure
• Right: text and layout/design editors
• Bottom: build result, debugging output

TIPS:

• A run down of various Android Studio’s View > Tool Windows, which also lists their keyboard shortcuts:
  • Project: the project navigation pane: the left pane.
  • Run: if you use println() in your code, it prints out on the Run panel.
  • Debug: println() also outputs here, along with a lot of other messages from Android’s subsystems, but if your app crashes, you can view the stack trace here along with the offending lines in your source code.
  • Problems: compile-time errors
  • Logcat: output of println(), Log.d(), and Log.e(). You can specify filter to show only certain messages.
  • Build: build error, library linking error.
  • Gradle: where you can generate your app’s SHA1.
  • Some useful keyboard shortcuts.
• For less clutter, especally on a small screen, you may want to disable everything in View > Appearance except Navigation Bar.
• On the left pane, under the gear icon, confirm that Tree Appearance > Hide Empty Middle Packages is selected.
• Then, under the same gear icon, select Open Files with Single Click and Always Select Opened File to make Android Studio feels a bit more responsive.
• Mouse over an API will pop up the API’s documentation
• The filenames on the navigation pane change colors according to whether it has been modified, committed, etc.

different screenshots

Depending on your version of Android Studio, the screenshots in our documentations may not look exactly the same as what you see on screen. If you are completely lost and cannot make sense of the screenshots, please consult the teaching staff.

See also Google’s Meet Android Studio for a thorough reference.

Running and debugging

On device

To enable USB debugging, on your Android phone tap on Settings > About Phone [> Software Info(rmation)] > Build Number seven times (and click your heels three times?) to enable the Developer options. Turn Developer options on and then turn on Settings > System > Developer Options. Turn on both Use developer options and USB debugging (and optionally Wireless debugging).

Android Studio supports WiFi pairing for debugging, which you activate using a QR code. If you don’t want to use a QR code, you can connect your device to Android Studio over WiFi using the plug-in ADB Wi-Fi which requires your phone to be connected by USB cable to be paired initially.

If you prefer to debug over a USB cable without WiFi, connect your device to your laptop. Android Studio should automatically recognize your device and use it to run your app. Click play to build and run.

See the Android Developers site for explanation of the remaining Developer options, though you can safely skip it at this point, except to turn on Stay awake.

On an emulator

1. Start the Device Manager from Tools > Device Manager on Android Studio’s main menu bar.
2. The left pane should open up on Android Studio. On the left pane, click Device Manager > Virtual > CREATE DEVICE “button” (screenshot).
3. Pick a Phone device listed with “Play Store” enabled and click NEXT (screenshot).

   Be sure to pick a device listed with “Play Store” enabled, otherwise your emulator will not work for labs 2 and 4. Pixel 6a, 7, and 7 Pro emulators are listed with Play Store enabled.

   by modifying config.ini

   You can also enable Play Store manually for your device of choice by following the instructions in this stackoverflow article.

4. Choose a system image. Choose EXACTLY API Level 33 (Release name: Tiramisu). Choose a system image listed with “(Google APIs)”. Click on the word Download next to Tiramisu in the Release Name column and then click FINISH and NEXT when done (screenshot).
5. Close the AVD Manager screen

Developer option on emulator

There shouldn’t be a need to turn on the Developer option on the emulator for any of the labs in this course, but in case you do need to turn it on, tap on Settings > About Phone > Build Number seven times and set Settings > System > Developer options > Use developer options on [thanks R. Ma F22].

Back in Android Studio, make sure your virtual device is selected in the box next to the green play button (screenshot).

To run your app

1. Hit the green play button
2. Play button changes icon to reload icon
3. To see the log, choose from the main menu View > Tools Window > Logcat
4. Click the stop button (seven positions to the right of the play button) on Android Studio to close the app (not the emulator)

To debug:

1. Instead of the play button, hit the bug button
2. To view the debug output, choose from the main menu View > Tools Window > Debug (this menu item shows up only when you’re debugging a process)

Running the labs on the Android emulator

If you have problem running the emulator, check out Troubleshooting and known issues for Android Emulator and system images.

Chatter and Images

There is no special set up necessary to run the basic Chatter lab (lab0) and the Images lab. The virtual camera on the emulator captures a stock scene for both photos and videos.

To use the emulator with the other labs, you need to access its Extended controls: click on the ... at the bottom of the right menu bar (screenshot).

Maps

To use the emulator with the Maps lab, you need to set two of the extended controls (click on the ... at the bottom of the right menu bar (screenshot)):

1. Location: to set the virtual location where you want your emulated device to be located:
   1. click on the Location menu item,
   2. search for your intended location,
   3. for ease of future re-location, you can click on SAVE POINT, give the location an easy to remember name, and click OK,
   4. click on SET LOCATION (screenshot with 5 saved points).

   Repeat the above process to switch to a different location (which should be picked up by the Maps lab).

2. Virtual sensors: to change the virtual facing of the emulated device, change its x-, y-, and z-rotations. The compass direction would likely not be accurate, but it does change as you rotate the emulated device around and this should be picked up by the Maps lab.

Audio

To record audio on the Android emulator, click the Microphone item on the extended controls menu and enable Virtual microphone uses host audio input (screenshot).

Signin

To use the emulator with the Signin/Biometric lab, click the Fingerprint item on the extended controls menu.

• You first need to register your virtual fingerprint with the emulated device as you would your real fingerprint on a physical device
  1. With the Fingerprint extended control window open, on the emulator’s Home Screen, scroll up to reveal the Launcher drawer and open the Settings app (screenshot).
  2. Search for Security and open it (screenshot).
  3. Then click on Pixel Imprint which should be in the second, DEVICE SECURITY section of the Security page (screenshot).
  4. On the next screen, choose to set up Pixel Imprint + PIN (screenshot).
  5. You will be asked to choose and enter a PIN, twice, and then to decide whether to have any notification shown on locked screen.
  6. After all that, you can finally register your virtual fingerprint, click NEXT (screenshot).
  7. When prompted to “Touch the Sensor” on the back of your phone (screenshot), go to the Extended controls window of the Android emulator (that you opened at the start of this process) and click on the TOUCH THE SENSOR button (screenshot).
  8. Keep on clicking on the TOUCH THE SENSOR button on the emulator’s extended control screen while the screen saying “Lift, then touch again” is up (screenshot).
  9. Once the virtual fingerprint is registered, you should see the “Fingerprint added” screen (screenshot).
  10. Click DONE and you should be back on the “Security” screen with “1 fingerprint set up” (screenshot). Congratulations!
• Running the “SignIn” lab, whenever you are prompted for the “Biometric ID” (screenshot), click on the TOUCH THE SENSOR" button on the emulator's Fingerprint` extended controls as you did previously when registering your virtual fingerprint (screenshot).

ARCore

To use the Android emulator with ARCore, please check out Installing ARCore on Android Emulator.

OpenGL ES

If your project builds on OpenGL ES, you may want to check out:

• OpenGL ES 2.0 Graphics Programming for Android - JAVA
• OpenGL ES 3.1 Graphics Programming for Android - Native

Publishing an Android app

GooglePlay’s Testing Tracks can be used for beta testing (even A/B test).

To publish your app, follow Google’s Publish your app instructions.

References

• Meet Android Studio
• Gradle Basics for Android Developers
• Why Android created emulator rather than simulator?
• Simulator or Emulator? What is the difference?
• How to install Google Play app in Android Studio emulator?

Publishing an Android app

• Google Play developer account
• GooglePlay’s Testing Tracks
• Publishing app to Play Store

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Prepared for EECS 441 by Alexander Wu, Mark Wassink, Yibo Pi, and Sugih Jamin

Last updated: January 9th, 2024