how to broadcast Receiver and MVVM?

Question

my manifest

<receiver android:name=".ui.receiver.NetworkChangeReceiver" >
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
            </intent-filter>
        </receiver>

and NetworkChangeReceiver Class

class NetworkChangeReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        val connMgr = context?.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val activeNetwork: NetworkInfo? = connMgr.activeNetworkInfo
        val isConnected: Boolean? = activeNetwork?.isConnected


        if(isConnected == null) {
            Timber.d("Test Checked is Connected null ")

        } else {
            Timber.d("Test Checked Network is Connected !! ")
        }
    }
}

I going to detect the network here.

If my mainViewModel detects what I've detected here, I'm trying to bring up an image, but I don't know what to do

Image is being visualized using live data and if the network changes here, I want to change the visibility of the image in my MainView Model.

Answer 1

1. define base class for LiveData of BroadcastReceiver

public class ReceiverLiveData<T> extends LiveData<T> {

    private final Context context;
    private final IntentFilter filter;
    private final BiFunction<Context, Intent, T> mapFunc;

    public ReceiverLiveData(Context context, IntentFilter filter, BiFunction<Context, Intent, T> mapFunc) {
        this.context = context;
        this.filter = filter;
        this.mapFunc = mapFunc;
    }

    @Override
    protected void onInactive() {
        super.onInactive();
        context.unregisterReceiver(mBroadcastReceiver);
    }

    @Override
    protected void onActive() {
        super.onActive();
        setValue(mapFunc.apply(context, new Intent()));
        context.registerReceiver(mBroadcastReceiver, filter);
    }

    private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            setValue(mapFunc.apply(context, intent));
        }
    };
}

2. declare your variable in ViewModel, for example battery change intent

    public static class ViewModel extends AndroidViewModel {
        public final LiveData<Intent> batteryIntentLiveData = new ReceiverLiveData<>(getApplication(), new IntentFilter(Intent.ACTION_BATTERY_CHANGED), (context, intent) -> intent);
        public final LiveData<NetworkInfo> activeNetworkInfoLiveData = new ReceiverLiveData<>(getApplication(), new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION), ((context, intent) -> ((ConnectivityManager) context.getSystemService(CONNECTIVITY_SERVICE)).getActiveNetworkInfo()));

        public ViewModel(@NonNull Application application) {
            super(application);
        }
    }

3. initialize ViewModel in Activity::onCreate

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityMainBinding binding = ActivityMainBinding.inflate(getLayoutInflater());
        binding.setViewModel(new ViewModelProvider(this).get(ViewModel.class));
        binding.setLifecycleOwner(this);
        setContentView(binding.getRoot());
    }

4. use batteryIntentLiveData & activeNetworkInfoLiveData in your DataBinding layout

<?xml version="1.0" encoding="utf-8"?>
<layout>

    <data>

        <variable
            name="viewModel"
            type="com.xxx.receiverbindingtest.MainActivity.ViewModel" />

        <import type="android.os.BatteryManager" />

        <import type="android.view.View" />
    </data>

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".MainActivity">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@{String.valueOf(viewModel.batteryIntentLiveData.getIntExtra(BatteryManager.EXTRA_LEVEL, 0))}" />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text='@{viewModel.batteryIntentLiveData.getIntExtra(BatteryManager.EXTRA_PLUGGED, 0) != 0 ? "Charging" : "Discharging"}' />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text='@{String.valueOf(viewModel.activeNetworkInfoLiveData.state)}'
            android:visibility="@{viewModel.activeNetworkInfoLiveData.connectedOrConnecting ? View.VISIBLE : View.GONE}" />

    </LinearLayout>
</layout>