Android Template

Latest version: https://git.ita.chalmers.se/courses/dit341/group-00-android (public Github mirror)

This Android templates contains a basic Android app with two activities and demonstrates a HTTP request to the Camel backend server.

Requirements

• Server backend running on http://localhost:3000
• Android Studio (v3.4)
  • Considerable bandwidth required for downloading Android Studio (~1GB), extra components (~700MB), project dependencies (~200MB) and a emulator system image (~1.1GB).

Project setup

1. Clone the template repository

   # Clone repository
   git clone [email protected]:courses/dit341/group-00-android.git
   
   # Change into the directory
   cd group-00-android

2. In Android Studio, Open an existing Android Studio project and select the template directory group-00-android

3. Wait for the first build to finish, which might take a while (few minutes) as Gradle downloads lots of dependencies.

4. Run the app by selecting Run -> Run 'Run app'

5. In the new window Select Deployment Target, create a new virtual device (emulator). Choose the Nexus 5X phone with API Level 28 (Android 9.0). Downloading this new system image might take a while.

6. Clicking Ok will automatically launch the device, deploy the app (as packaged apk), and start the main activity of the app.

Checkout Run apps on a hardware device to run your app on your Android device.

Project structure

• manifests - Contains the AndroidManifest.xml. This file has all the definitions (of Activities etc.)
• java - Contains all the Java files. There is a folder for the actual App, and two test folders.
• res - Contains the resources. The layout sub-folders contains the xml UI definitions. values contains value definitions (e.g., strings).

Notice that the physical directory structure is slightly different than this Android Studio view.

Creating an Activity, Service, etc. in Android Studio (right-click on the root or java folder -> New -> Activity -> Empty Acitivity) automatically creates the UI file, the Java file, and the corresponding definition in the manifest.

HTTP Requests

Clicking the Get Camels button in the main activity performs an HTTP GET request to the camel backend. It uses the URL defined in res/values/urls.xml. By default, it uses the IP address 10.0.2.2. This is the IP address pointing from the Android Emulator to the machine running it (basically, the localhost on your computer).

If you have your app running on an actual device, you will have to have both the device and your computer running in the same network and point the URL to the computer IP. Additionally, you will have to disable any firewall rules that block external HTTP request to your HTTP port (e.g., 3000). This does not work within eduroam/NOMAD.

onClick Listeners

In Android, buttons are connected to methods using so-called Listeners. If you open any of the UI XML definitions (e.g., res/layour/acitivity_main.xml) and click on a button, you can assign a method name to the onClick property in the Attributes tab. This will then execute the method with the same name in the Activity's Java file whenever the button is clicked. The method needs to have return parameter void and an input parameter View view.

Testing

1. Right-click the test directory and select Run 'Run unit tests''
2. Right-click the androidTest directory and select Run 'Run instrumented tests''

You can also select different run profiles via the menu Run -> Run...

Debugging

1. Set a breakpoint in Android Studio
2. Run the app by selecting Run -> Debug 'app'

Read more in the Android debug docs or try the Android debugger tutorial