Introduction to Android development

App structure

build.gradle

• Contains dependencies fetched by Gradle ("package.json like")

• App configuration:

applicationId "test.florian.androidtestapp"
minSdkVersion 15
targetSdkVersion 23
versionCode 1
versionName "1.0"

AndroidManifest.xml

• Permissions

• Application

• Activities

Activity

part of the application's visual user interface

<intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

Main activity:

public class LoginActivity extends AppCompatActivity {
    //...

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(...); // Create interface
    }
}

~ Angular/Ionic controller, React Native smart component/page

Layouts

defines the visual structure for a user interface, such as the UI for an activity or app widget

• XML based layouts
• "Flexbox" :

• R.id.* to access elements in the Java classes

• Designer in Android Studio

Fragments

piece of an application's user interface or behavior that can be placed in an Activity

• Can be designed with the Designer too

• Using the same XML based layouts

• Lifecycle tied to the activity using it

Intent

• Launch other activities of the app

• Launch another app

• Intent can have parameters ("extra")

startActivity(new Intent(view.getContext(), TabActivity.class));

Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

Debugging

adb logcat/pidcat/Android monitor tab in Android Studio

First step: read the logs

Debugger integrated to the IDE

Read media files

MediaStore

final Cursor cursor = context.getContentResolver().query(
    MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null, null);

https://github.com/bamlab/rn-camera-roll/blob/master/android/src/main/java/fr/bamlab/rncameraroll/CameraImagesManager.java

HTTP requests

AsyncHttpClient looks nice

AsyncHttpClient asyncHttpClient = new DefaultAsyncHttpClient();
asyncHttpClient.prepareGet("http://www.example.com/").execute(
new AsyncCompletionHandler<Response>(){
    public Response onCompleted(Response response) throws Exception{
        // Do something with the Response
        return response;
    }

    public void onThrowable(Throwable t){
        // Something wrong happened.
    }
});

https://github.com/bamlab/chooz-it-app/blob/chooz-integration/android/app/src/main/java/fr/bamlab/fileuploadandroid/FileUploader.java

Proguard

• Beware of shrinking

• Shrink/obfuscate code

when making method to interface with Javascript

Thanks :)