Forem: Ochornma Promise

Closures in Swift

Ochornma Promise — Sat, 15 May 2021 15:33:13 +0000

According to the swift official documentation

Closures are self-contained blocks of functionality that can be passed around and used in your code.

They are similar to lambda in other languages and can be used in higher order functions.
In swift, you can represent a function as a variable using closure.
Using the code snippets below, we are going to go from writing a function to writing a closure and at such learn how to convert a function into a closure.

func fullName(firstName: String, lastName: String) -> String{
  return "The Full Name is \(firstName) \(lastName)"
}

print(fullName(firstName: "Promise", lastName: "Ochornma"))

//The Result is:
//The Full Name is Promise Ochornma

The code above is a function that concatenates first name and last name into a full name.
We will now convert it to a closure as shown below.

let fullName: (String, String) -> String = { (firstName, lastName) in
   return "The Full Name is \(firstName) \(lastName)"
}

print(fullName("Promise", "Ochornma"))

//The Result is:
//The Full Name is Promise Ochornma

In the above code snippet, we have converted the function fullName to a variable named fullName using closure.
Both codes prints out same result
“The Full Name is Promise Ochornma”
We can also simplify the closures by using the dollar sign as seen in the code snippet below.
Note that the first parameter is represented with $0, the second parameter $1. That means if we have n number of parameters, you can access at position p each using $p-1 and the full parameters will be in the range of $0…$n-1

let fullName: (String, String) -> String = {
   return "The Full Name is \($0) \($1)"
}

print(fullName("Promise", "Ochornma"))

//The Result is:
//The Full Name is Promise Ochornma

Arrays of closure

Since a closure is a function represented as a variable, you can create an array of closures.
According to swift documentation

An array stores values of the same type in an ordered list. The same value can appear in an array multiple times at different positions.

This means that all closures in the array must be of same type and a particular closure can be in different positions.
Just like your usual array, you can Iterating over the array using for-in loop, add two arrays using the + symbol and also add a new item using the append method
Let us now create an array of closures and see how to use them.

let plus: (Int, Int) -> Int = {
  return $0 + $1
}

let minus: (Int, Int) -> Int = {
  return $0 - $1
}

let add: (Int, Int) -> Int = {
  return $0 + $1
}

let subtract: (Int, Int) -> Int = {
  return $0 - $1
}

let closureFunctions = [ plus, minus ]

let plusSign = closureFunctions[0]
print(plusSign(1, 5))
//result is:
//6
//The append method
closureFunctions.append(add)
closureFunctions.append(subtract)

print(closureFunctions.count)
//result is:
//4
for closure in closureFunctions {
   print(closure(6,5))
}
//result is:
//11
//1
//11
//1
let addition: (Int, Int) -> Int = {
  return $0 + $1
}

let subtraction: (Int, Int) -> Int = {
  return $0 - $1
}

let closureFunctions2= [ addition, subtraction ]

let newClosureFunction = closureFunctions + closureFunctions2
print(newClosureFunction.count)
//result is:
//6

Dictionary of Closures

According to swift documentation

A dictionary stores associations between keys of the same type and values of the same type in a collection with no defined ordering. Each value is associated with a unique key, which acts as an identifier for that value within the dictionary. Unlike items in an array, items in a dictionary don’t have a specified order. You use a dictionary when you need to look up values based on their identifier, in much the same way that a real-world dictionary is used to look up the definition for a particular word.

let plus: (Int, Int) -> Int = {
  return $0 + $1
}

let minus: (Int, Int) -> Int = {
  return $0 - $1
}

let add: (Int, Int) -> Int = {
  return $0 + $1
}

let subtract: (Int, Int) -> Int = {
  return $0 - $1
}

let closureFunctions = ["plus": plus, "minus" : minus ]

let plusSign = closureFunctions["plus"]
print(plusSign(1, 5))
//result is:
//6

//Add a new value to the dictionary
closureFunctions["add"] = add
closureFunctions["subtract"] = subtract

print(closureFunctions.count)
//result is:
//4

for (key, value) in closureFunctions {
  print("(\(key),\(value(5, 6)))")
}
//result is:
//(plus, 11)
//(minus, 1)
//(add, 11)
//(subtract, 1)

Wearable RecyclerView

Ochornma Promise — Thu, 16 Jul 2020 06:21:06 +0000

The Wearable UI Library includes the WearableRecyclerView class, which is a RecyclerView implementation for creating lists optimized for wearable devices. You can use this interface in your wearable app by creating a new WearableRecyclerView container.

Wearable recyclerview is used to create a circular layout and is an alternative to Boxlayout on Circular WearOS.
The most used public methods of this view are:

setCircularScrollingGestureEnabled(boolean): For enabling/disabling circular touch scrolling for this view.
setEdgeItemsCenteringEnabled(boolean): This method is used to indicate if the view should always align the first and last items with the vertical center of the screen. Below I will give an example with the Home screen of DCLM Watch

First the layout file and then the list item, the Adapter and the Activity

<?xml version="1.0" encoding="utf-8"?>
<layout 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">
    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.wear.widget.WearableRecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="#000"
            android:scrollbars="vertical"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <ImageView
            android:id="@+id/background"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:alpha="0.10"
            android:scaleType="fitXY"
            android:src="@drawable/nlogo"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.0"
            tools:ignore="ContentDescription" />



    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

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

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/menu_container"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <import type="androidx.core.content.ContextCompat"/>
        <variable
            name="data"
            type="org.dclm.live.watch.MainScreen" />
    </data>
    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:color/transparent">
        <!--   -->
        <!-- -->

        <ImageView
            android:id="@+id/menu_icon"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:background="@android:color/transparent"
            android:src="@{ContextCompat.getDrawable(context, data.drawable)}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:ignore="HardcodedText" />

        <TextView
            android:id="@+id/menu_item"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="5dp"
            android:text="@={data.heading}"
            android:textColor="#fff"
            android:textSize="13sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/menu_icon"
            app:layout_constraintTop_toTopOf="@+id/menu_icon"
            tools:text="swsssswxwx masxsag sxsxbvx" />

        <TextView
            android:id="@+id/menu_sub"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="5dp"
            android:text="@={data.category}"
            android:textColor="#fff"
            android:textSize="12sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/menu_icon"
            app:layout_constraintTop_toBottomOf="@+id/menu_item"
            tools:text="swsssswxwx " />



    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

class MainActivity : WearableActivity() {
    private lateinit var binding: ActivityMainBinding
    private lateinit var adapter:MainAdapter
    private lateinit var mainScreen: MutableList<MainScreen>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
        mainScreen = ArrayList<MainScreen>()
        mainScreen.add(MainScreen(1, R.drawable.nlogo2, getString(R.string.app_radio)))
        mainScreen.add(MainScreen(2, R.drawable.baba, getString(R.string.recent_sermons)))
        adapter = MainAdapter(mainScreen, this)
        binding.recyclerView.isEdgeItemsCenteringEnabled = true
        binding.recyclerView.layoutManager = WearableLinearLayoutManager(this)
        binding.recyclerView.isCircularScrollingGestureEnabled = true;
        binding.recyclerView.isEdgeItemsCenteringEnabled = true
        binding.recyclerView.adapter = adapter

        setAmbientEnabled()
    }

    override fun onExitAmbient() {
        super.onExitAmbient()


    }

    override fun onEnterAmbient(ambientDetails: Bundle?) {
        super.onEnterAmbient(ambientDetails)


    }
}

data class MainScreen(var id: Int, var image: Int, var name: String)

class MainAdapter(val main: MutableList<MainScreen>, val context: Context): RecyclerView.Adapter<MainAdapter.Holder>() {


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
        val binding = DataBindingUtil.inflate<ListItemBinding>(LayoutInflater.from(context), R.layout.list_item, parent, false)
        return Holder(binding)
    }

      override fun getItemCount() = main.size

    override fun onBindViewHolder(holder: Holder, position: Int) {
        val main1 = main[position]
        holder.binding.data = main1
        holder.binding.root.setOnClickListener {
            context.apply {
                if (main1.id == 1){
                    startActivity(Intent())
                } else{
                    startActivity(Intent())
                }
            }

        }
    }

    class Holder(val binding: ActivityMainListBinding) : RecyclerView.ViewHolder(binding.root) {

    }
}

If you need to implement custom child layout behavior on scroll, then you can use then you use this constructor WearableLinearLayoutManager(Context context, LayoutCallback layoutCallback)and then set your custom Layout Callback as the parameter for the layoutCallback. You can trust Android Magic by coping theirs as your custom LayoutCallback

/** How much should we scale the icon at most.  */
private const val MAX_ICON_PROGRESS = 0.65f

class CustomScrollingLayoutCallback : WearableLinearLayoutManager.LayoutCallback() {

    private var progressToCenter: Float = 0f

    override fun onLayoutFinished(child: View, parent: RecyclerView) {
        child.apply {
            // Figure out % progress from top to bottom
            val centerOffset = height.toFloat() / 2.0f / parent.height.toFloat()
            val yRelativeToCenterOffset = y / parent.height + centerOffset

            // Normalize for center
            progressToCenter = Math.abs(0.5f - yRelativeToCenterOffset)
            // Adjust to the maximum scale
            progressToCenter = Math.min(progressToCenter, MAX_ICON_PROGRESS)

            scaleX = 1 - progressToCenter
            scaleY = 1 - progressToCenter
        }
    }
}

Developing android radio app

Ochornma Promise — Thu, 26 Dec 2019 18:32:16 +0000

I, decided to pen down my thoughts and experience from developing the DCLM Radio app.

To develop a radio app, it is important to seek permission for foreground service, wake lock and internet.

<uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/nlogo"
        android:label="@string/app_name"
        android:networkSecurityConfig="@xml/network_security_config"
        android:supportsRtl="true"
        android:usesCleartextTraffic="true"
        tools:targetApi="m">
        <uses-library
            android:name="org.apache.http.legacy"
            android:required="false" />

From android documentation, the android:networkSecurityConfig

“lets apps customize their network security settings in a safe, declarative configuration file without modifying app code. These settings can be configured for specific domains and for a specific app.”
From the documentation, the followings are the key capabilities of this feature
Custom trust anchors:
Customize which Certificate Authorities (CA) are trusted for an app’s secure connections. For example, trusting particular self-signed certificates or restricting the set of public CAs that the app trusts.
Debug-only overrides: Safely debug secure connections in an app without added risk to the installed base.
Cleartext traffic opt-out: Protect apps from accidental usage of cleartext traffic.
Certificate pinning: Restrict an app’s secure connection to particular certificates.

From my experience, this is necessary if the domain throws http and you need your app to function on Android 8 and above. Below is a format for the network configuration xml file.

<network-security-config>
    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">domain name without https://</domain>
    </domain-config>
</network-security-config>

I optimized the app to function on standalone Wear OS. To do this, I added a new module from the file menu > New > New Module and then selected the WearOS Module. then updated the build.gradle of the wear mode with the following

implementation 'androidx.wear:wear:1.0.0'
implementation 'com.google.android.support:wearable:2.5.0'
compileOnly 'com.google.android.wearable:wearable:2.5.0'

Then the WearOS manifest file updated to allow the app run WearOS

<uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-feature android:name="android.hardware.type.watch" />

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

    <application
        android:allowBackup="true"
        android:networkSecurityConfig="@xml/network_security_config"
        android:supportsRtl="true"
        android:usesCleartextTraffic="true"
        tools:targetApi="m">
        <uses-library
            android:name="com.google.android.wearable"
            android:required="false" />

        <uses-library
            android:name="org.apache.http.legacy"
            android:required="false" />

        <!--
               Set to true if your app is Standalone, that is, it does not require the handheld
               app to run.
        -->
        <meta-data
            android:name="com.google.android.wearable.standalone"
            android:value="true" />

For the app to work both on square and round wearOS, you need this attribute boxedEdges on the wearOS layout file.


app:boxedEdges="all"

I used the Exoplayer library as against the Android multimedia framework (MediaPlayer).
The Exoplayer supports DASH Streaming, HLS which are not supported by MediaPlayer.
Below is the layout for the app

<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:background="@drawable/uiradio"
    android:orientation="vertical">
    <com.google.android.material.appbar.AppBarLayout
        android:elevation="0dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        tools:targetApi="lollipop">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/app_bar"
            style="@style/Widget.DCLM.Toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:navigationIcon="@drawable/nlogo11"
            app:title="@string/app_name" />
    </com.google.android.material.appbar.AppBarLayout>

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:elevation="8dp"
        tools:targetApi="lollipop">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="120dp"
            android:layout_height="120dp"
            android:layout_marginStart="8dp"
            android:layout_marginTop="30dp"
            android:layout_marginEnd="8dp"
            android:src="@drawable/nlogo"
            android:contentDescription="@string/image_view_dclm_logo"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />


        <ImageButton
            android:id="@+id/play"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@android:color/transparent"
            android:contentDescription="@string/play_button"
            android:src="@drawable/ic_play"
            app:layout_constraintBottom_toTopOf="@+id/up_next"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/preacher" />


        <Button
            android:id="@+id/live"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="4dp"
            android:background="@android:color/transparent"
            android:contentDescription="@string/stop_button"
            android:text="@string/live"
            android:textAllCaps="true"
            android:textAppearance="?attr/textAppearanceBody1"
            android:textColor="@color/colorAccent"
            android:textSize="20sp"
            android:textStyle="bold"
            android:visibility="invisible"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/stop" />

        <ImageButton
            android:id="@+id/stop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@android:color/transparent"
            android:contentDescription="@string/stop_button"
            android:src="@drawable/ic_pause"
            android:visibility="invisible"
            app:layout_constraintBottom_toTopOf="@+id/up_next"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/preacher" />


        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="12dp"
            android:fontFamily="sans-serif-condensed-medium"
            android:paddingLeft="8dp"
            android:paddingRight="8dp"
            android:textAlignment="center"
            android:textColor="#fff"
            android:textAppearance="@style/TextAppearance.DCLM.Title"
            android:textSize="15sp"
            android:textStyle="normal|bold"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/imageView" />


        <TextView
            android:id="@+id/preacher"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="4dp"
            android:fontFamily="sans-serif-condensed-medium"
            android:textSize="20sp"
            android:textColor="#fff"
            android:paddingLeft="8dp"
            android:paddingRight="8dp"
            android:textStyle="normal"
            android:textAppearance="?attr/textAppearanceBody2"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/title" />

        <TextView
            android:id="@+id/up_next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="4dp"
            android:textColor="#fff"
            android:textSize="15sp"
            android:textAppearance="?attr/textAppearanceSubtitle1"
            app:layout_constraintBottom_toTopOf="@+id/tittle_next"
            app:layout_constraintTop_toBottomOf="@+id/live"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />

        <TextView
            android:id="@+id/tittle_next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="16dp"
            android:textAlignment="center"
            android:textColor="#fff"
            android:textSize="15sp"
            android:textAppearance="?attr/textAppearanceSubtitle2"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />




    </androidx.constraintlayout.widget.ConstraintLayout>

    </ScrollView>

</LinearLayout>

Since the app will be playing on background even when the activity lifecycle is in onStop state we will need the Android service.
We will be using the Foreground service and will be bounding it to the MainActivity.

public class RadioService extends Service {

    private final IBinder binder2 = new RadioLocalBinder();

    public SimpleExoPlayer player;
    private PlayerNotificationManager playerNotificationManager;
    private MediaSessionCompat mediaSession;
    private MediaSessionConnector mediaSessionConnector;
    private Context context;
    private boolean check;
    private  MediaSource mediaSource;


    @Override
    public void onCreate() {
        super.onCreate();
        context = this;

        AudioAttributes audioAttributes = new AudioAttributes.Builder()
                .setUsage(com.google.android.exoplayer2.C.USAGE_MEDIA)
                .setContentType(com.google.android.exoplayer2.C.CONTENT_TYPE_SPEECH)
                .build();

        player = ExoPlayerFactory.newSimpleInstance(this);
        player.setAudioAttributes(audioAttributes,true);

    }

    public void prepare(){
        String userAgent = Util.getUserAgent(context, "DCLM Radio");

        DefaultHttpDataSourceFactory httpDataSourceFactory = new DefaultHttpDataSourceFactory(
                userAgent,
                null /* listener */,
                30 * 1000,
                30*1000,
                true  //allowCrossProtocolRedirects
        );

        mediaSource = new ProgressiveMediaSource.Factory(httpDataSourceFactory)
                .createMediaSource(Uri.parse(getString(R.string.radio_link)));
        player.prepare(mediaSource);
        player.setPlayWhenReady(true);

    }


    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return binder2;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
         check = true;
            String userAgent = Util.getUserAgent(context, getString(R.string.app_name));

// Default parameters, except allowCrossProtocolRedirects is true

            DefaultHttpDataSourceFactory httpDataSourceFactory = new DefaultHttpDataSourceFactory(
                    userAgent,
                    null /* listener */,
                    30 * 1000, 
                    30*1000,
                    true  //allowCrossProtocolRedirects
            );


            mediaSource = new ProgressiveMediaSource.Factory(httpDataSourceFactory)
                    .createMediaSource(Uri.parse(getString(R.string.radio_link)));
            player.prepare(mediaSource);

            playerNotificationManager = PlayerNotificationManager.createWithNotificationChannel(context, "playback_channel",
                    R.string.app_name, R.string.app_describe, 1, new PlayerNotificationManager.MediaDescriptionAdapter() {
                        @Override
                        public String getCurrentContentTitle(Player player) {
                            return getString(R.string.app_name);
                        }

                        @Nullable
                        @Override
                        public PendingIntent createCurrentContentIntent(Player player) {
                            Intent intent = new Intent(context, MainActivity.class);
                          intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK)
                            return PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
                        }

                        @Nullable
                        @Override
                        public String getCurrentContentText(Player player) {
                            return getString(R.string.app_describe);
                        }

                        @Nullable
                        @Override
                        public Bitmap getCurrentLargeIcon(Player player, PlayerNotificationManager.BitmapCallback callback) {
                            return getBitmap(context, R.drawable.nlogo);
                        }
                    }, new PlayerNotificationManager.NotificationListener() {
                        @Override
                        public void onNotificationCancelled(int notificationId, boolean dismissedByUser) {
                          stopForeground(true);
                        }

                        @Override
                        public void onNotificationPosted(int notificationId, Notification notification, boolean ongoing) {
                            startForeground(notificationId, notification);
                        }
                    });


            playerNotificationManager.setSmallIcon(R.drawable.nlogo);
            playerNotificationManager.setUseStopAction(true);
            playerNotificationManager.setUseNavigationActions(false);
            playerNotificationManager.setUseStopAction(false);
            playerNotificationManager.setPlayer(player);
            mediaSession = new MediaSessionCompat(context, "dclm_radio");
            mediaSession.setActive(true);
            playerNotificationManager.setMediaSessionToken(mediaSession.getSessionToken());
            mediaSessionConnector = new MediaSessionConnector(mediaSession);
            mediaSessionConnector.setPlayer(player);
        MediaButtonReceiver.handleIntent(mediaSession, intent);
        return START_STICKY;
    }

    public static Bitmap getBitmap(Context context, @DrawableRes int bitmapResource) {
        return ((BitmapDrawable) context.getResources().getDrawable(bitmapResource)).getBitmap();
    }

    public class RadioLocalBinder extends Binder {
        DCLMRadioService getService2(){
            // Return this instance of LocalService so clients can call public methods
            return DCLMRadioService.this;
        }
    }

    public void pausePlayer(){
        if(player.isPlaying()) {
            player.setPlayWhenReady(false);
            player.getPlaybackState();
        }
    }
    public void startPlayer(){
        if(!player.isPlaying()) {
            player.setPlayWhenReady(true);
            player.getPlaybackState();
        }
    }

        @Override
    public void onDestroy() {
        if(check){
            mediaSession.release();
            mediaSessionConnector.setPlayer(null);
            playerNotificationManager.setPlayer(null);
            player.release();
        }
        player = null;
        super.onDestroy();
    }
}

For the audio focus I choose C.CONTENT_TYPE_SPEECH since I want the radio to pause, when another audio is played since it is a podcast. There are other types you can choose such as C.CONTENT_TYPE_MOVIE, C.CONTENT_TYPE_MUSIC, C.CONTENT_TYPE_SONIFICATIONor C.CONTENT_TYPE_UNKNOWN.
I also increased the DefaultHttpDataSourceFactory connection and read timeout to 30 Seconds because the default time was giving socket timeout exception (Caused by: java.net.SocketTimeoutException: connect timed out)
For the onDestroy, I used the boolean check to detect if the mediaSession, mediaSessionConnector, playerNotificationManager and the player is not null.
If they are null, trying to release those resources will throw a nullpointer exception

public class MainActivity extends AppCompatActivity {

    public static final String PREFRENCES = "com.dclm.radio";

    public Boolean isOnline;
    private Intent intent;
    RadioService radioService;
    boolean mBound = false;
    private ImageButton buttonPlay, buttonPause;
    private Button buttonLive
    private SharedPreferences sharedPreferences;
    // Record whether audio is playing or not.
    private int audioIsPlaying;

    private ServiceConnection connection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName className,
                                       IBinder service2) {
            // We've bound to LocalService, cast the IBinder and get LocalService instance
            RadioService.RadioLocalBinder binder2 = (RadioService.RadioLocalBinder) service2;
            radioService = binder2.getService2();
            mBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName arg0) {
            mBound = false;
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //registerUpdateOnNetwork();

        //stopping();
        audioIsPlaying = 0;
        sharedPreferences = getSharedPreferences(PREFRENCES, Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putInt("audioIsPlaying", audioIsPlaying);
        editor.apply();

// find the views of the listed i.e initialize the views
        buttonPlay = findViewById(R.id.play);
        buttonPause = findViewById(R.id.stop);
        buttonlive = findViewById(R.id.live);
        buttonPause.setVisibility(View.INVISIBLE);
        buttonlive.setVisibility(View.INVISIBLE);

        // seek the onclick listener for the button

        buttonPlay.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SharedPreferences prefs = getSharedPreferences(PREFRENCES, MODE_PRIVATE);
                int resume = prefs.getInt("audioIsPlaying", 0); //0 is the default value.
                if(resume != 10){
                    intent = new Intent(MainActivity.this, RadioService.class);
                    Util.startForegroundService(MainActivity.this, intent);
                }
                    int state = dclmRadioService.player.getPlaybackState()
                        buttonPlay.setVisibility(View.INVISIBLE);
                        buttonPause.setVisibility(View.VISIBLE);
                        buttonlive.setVisibility(View.VISIBLE);
                            if (state == Player.STATE_READY) {
                                radioService.startPlayer();
                                audioIsPlaying = 10;
                                SharedPreferences.Editor editor = sharedPreferences.edit();
                                editor.putInt("audioIsPlaying", audioIsPlaying);
                                editor.apply();
                            } else if (state == Player.STATE_IDLE) {
                                intent = new Intent(MainActivity.this, RadioService.class);
                                Util.startForegroundService(MainActivity.this, intent);
                                //dclmRadioService.prepare();
                                Handler mHandler = new Handler(getMainLooper());
                                mHandler.post(new Runnable() {
                                    @Override
                                    public void run() {
                                        dclmRadioService.startPlayer();
                                    }
                                });

                                audioIsPlaying = 10;
                                SharedPreferences.Editor editor = sharedPreferences.edit();
                                editor.putInt("audioIsPlaying", audioIsPlaying);
                                editor.apply();
                            } else if (state == Player.STATE_ENDED) {
                                intent = new Intent(MainActivity.this, RadioService.class);
                                Util.startForegroundService(MainActivity.this, intent);
                                radioService.startPlayer();
                            }
                }

        });


        buttonPause.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                buttonPause.setVisibility(View.INVISIBLE);
                buttonPlay.setVisibility(View.VISIBLE);
                Handler mHandler = new Handler(getMainLooper());
                mHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        dclmRadioService.pausePlayer();
                    }
                });
                int state2 = radioService.player.getPlaybackState();
            }
        });

        buttonlive.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dclmRadioService.prepare();
                buttonPlay.setVisibility(View.INVISIBLE);
                buttonPause.setVisibility(View.VISIBLE);
            }
        });

}

    @Override
    protected void onResume() {
        super.onResume();
        SharedPreferences prefs = getSharedPreferences(PREFRENCES, MODE_PRIVATE);
        int resume = prefs.getInt("audioIsPlaying", 0); //0 is the default value.
        if(resume == 10) {

            boolean remain = radioService.isPlaying();
           Log.i("Main", String.valueOf(remain));
           if (!remain){
                buttonPause.setVisibility(View.VISIBLE);
                buttonPlay.setVisibility(View.INVISIBLE);
            } else {
               buttonPause.setVisibility(View.INVISIBLE);
               buttonPlay.setVisibility(View.VISIBLE);
           }
        }
    }

    @Override
    protected void onStart() {
        super.onStart();
        // Bind to DCLMService
        Intent intent = new Intent(this, RadioService.class);
        bindService(intent, connection, BIND_AUTO_CREATE);
    }



    @Override
    protected void onStop() {
        super.onStop();
        if(audioIsPlaying != 5) {
            unbindService(connection);
            mBound = false;
        }
    }

    @Override
    public void onBackPressed() {
            Intent setIntent = new Intent(Intent.ACTION_MAIN);
            setIntent.addCategory(Intent.CATEGORY_HOME);
            setIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(setIntent);
    }

    @Override
    protected void onDestroy() {
        intent = new Intent(MainActivity.this, RadioService.class);
        stopService(intent);
        super.onDestroy();
    }
}

Above is the MainActivity of the app. It is bounded to the service at the onStart lifecycle of the app and unbounded in the onStop.

It is important to check if the WearOS has an inbuilt speaker device before starting the background service as this is one of the prerequisite for developing a media player for WearOS as stated on Android guide for WearOS

PackageManager packageManager = getPackageManager();
            // The results from AudioManager.getDevices can't be trusted unless the device
            // advertises FEATURE_AUDIO_OUTPUT.
            if (!packageManager.hasSystemFeature(PackageManager.FEATURE_AUDIO_OUTPUT)) {
                return false;
            }
            AudioManager audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
            AudioDeviceInfo[] devices = audioManager.getDevices(AudioManager.GET_DEVICES_OUTPUTS);
            for (AudioDeviceInfo device : devices) {
                if (device.getType() == AudioDeviceInfo.TYPE_BUILTIN_SPEAKER) {
                    return true;
                }
            }

Whenever the app is destroyed, the background service is stopped/destroyed (stopService()).

The exoplayer/service is started using the Util.startForegroundService(MainActivity.this, intent);

Note: if the service need to be stated before it can persist even when the app is in onStop state and that’s the reason the player is started in the onStartCommand of the RadioService even the Notification, media session and media session connector
The buttonLive is used to recreate the player, if the app has been paused for a long time. It is intended to imitate the YouTube live button.