Prerequisite Create a UI for Sending Messages Apply View Binding Manage Chat-Message Requests Final Steps

IVS Chat Client Messaging SDK: Kotlin Coroutines Tutorial Part 2: Messages and Events

This second (and last) part of the tutorial is broken up into several sections:

Create a UI for Sending Messages
Apply View Binding
Manage Chat-Message Requests
Final Steps

For full SDK documentation, start with Amazon IVS Chat Client Messaging SDK (here in the Amazon IVS Chat User Guide) and the Chat Client Messaging: SDK for Android Reference (on GitHub).

Prerequisite

Be sure you have completed Part 1 of this tutorial, Chat Rooms.

Create a UI for Sending Messages

Now that we successfully initialized the chat room connection, it’s time to send our first message. For this feature, a UI is needed. We will add:

connect/disconnect button
Message input with send button
Dynamic messages list. To build this, we use Android Jetpack RecyclerView.

UI Main Layout

See Android Jetpack Layouts in the Android developer documentation.

XML:


// ./app/src/main/res/layout/activity_main.xml


<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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">

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
                  xmlns:app="http://schemas.android.com/apk/res-auto"
                  android:id="@+id/connect_view"
                  android:layout_width="match_parent"
                  android:layout_height="match_parent"
                  android:gravity="center"
                  android:orientation="vertical">

        <androidx.cardview.widget.CardView
                android:id="@+id/connect_button"
                android:layout_width="match_parent"
                android:layout_height="48dp"
                android:layout_gravity=""
                android:layout_marginStart="16dp"
                android:layout_marginTop="4dp"
                android:layout_marginEnd="16dp"
                android:clickable="true"
                android:elevation="16dp"
                android:focusable="true"
                android:foreground="?android:attr/selectableItemBackground"
                app:cardBackgroundColor="@color/purple_500"
                app:cardCornerRadius="10dp">

            <TextView
                    android:id="@+id/connect_text"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentEnd="true"
                    android:layout_gravity="center"
                    android:layout_weight="1"
                    android:paddingHorizontal="12dp"
                    android:text="Connect"
                    android:textColor="@color/white"
                    android:textSize="16sp"/>

            <ProgressBar
                    android:id="@+id/activity_indicator"
                    android:layout_width="20dp"
                    android:layout_height="20dp"
                    android:layout_gravity="center"
                    android:layout_marginHorizontal="20dp"
                    android:indeterminateOnly="true"
                    android:indeterminateTint="@color/white"
                    android:indeterminateTintMode="src_atop"
                    android:keepScreenOn="true"
                    android:visibility="gone"/>
        </androidx.cardview.widget.CardView>

    </LinearLayout>

    <androidx.constraintlayout.widget.ConstraintLayout
            android:id="@+id/chat_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:clipToPadding="false"
            android:visibility="visible"
            tools:context=".MainActivity">

        <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical"
                app:layout_constraintBottom_toTopOf="@+id/layout_message_input"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent">

            <androidx.recyclerview.widget.RecyclerView
                    android:id="@+id/recycler_view"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:clipToPadding="false"
                    android:paddingTop="70dp"
                    android:paddingBottom="20dp"/>
        </RelativeLayout>

        <RelativeLayout
                android:id="@+id/layout_message_input"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@android:color/white"
                android:clipToPadding="false"
                android:drawableTop="@android:color/black"
                android:elevation="18dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintStart_toStartOf="parent">

            <EditText
                    android:id="@+id/message_edit_text"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_centerVertical="true"
                    android:layout_marginStart="16dp"
                    android:layout_toStartOf="@+id/send_button"
                    android:background="@android:color/transparent"
                    android:hint="Enter Message"
                    android:inputType="text"
                    android:maxLines="6"
                    tools:ignore="Autofill"/>

            <Button
                    android:id="@+id/send_button"
                    android:layout_width="84dp"
                    android:layout_height="48dp"
                    android:layout_alignParentEnd="true"
                    android:background="@color/black"
                    android:foreground="?android:attr/selectableItemBackground"
                    android:text="Send"
                    android:textColor="@color/white"
                    android:textSize="12dp"/>
        </RelativeLayout>
    </androidx.constraintlayout.widget.ConstraintLayout>


</androidx.coordinatorlayout.widget.CoordinatorLayout>

UI Abstracted Text Cell to Display Text Consistently

XML:


// ./app/src/main/res/layout/common_cell.xml
   
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:id="@+id/layout_container"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:background="@color/light_gray"
              android:minWidth="100dp"
              android:orientation="vertical">

    <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="horizontal">

        <TextView
                android:id="@+id/card_message_me_text_view"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_marginBottom="8dp"
                android:maxWidth="260dp"
                android:paddingLeft="12dp"
                android:paddingTop="8dp"
                android:paddingRight="12dp"
                android:text="This is a Message"
                android:textColor="#ffffff"
                android:textSize="16sp"/>

        <TextView
                android:id="@+id/failed_mark"
                android:layout_width="40dp"
                android:layout_height="match_parent"
                android:paddingRight="5dp"
                android:src="@drawable/ic_launcher_background"
                android:text="!"
                android:textAlignment="viewEnd"
                android:textColor="@color/white"
                android:textSize="25dp"
                android:visibility="gone"/>
    </LinearLayout>

</LinearLayout>

UI Left Chat Message

XML:


// ./app/src/main/res/layout/card_view_left.xml
 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:app="http://schemas.android.com/apk/res-auto"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginStart="8dp"
              android:layout_marginBottom="12dp"
              android:orientation="vertical">

    <TextView
            android:id="@+id/username_edit_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="UserName"/>

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

        <androidx.cardview.widget.CardView
                android:id="@+id/card_message_other"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="left"
                android:layout_marginBottom="4dp"
                android:foreground="?android:attr/selectableItemBackground"
                app:cardBackgroundColor="@color/light_gray_2"
                app:cardCornerRadius="10dp"
                app:cardElevation="0dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintStart_toStartOf="parent">

            <include layout="@layout/common_cell"/>
        </androidx.cardview.widget.CardView>

        <TextView
                android:id="@+id/dateText"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="4dp"
                android:layout_marginBottom="4dp"
                android:text="10:00"
                app:layout_constraintBottom_toBottomOf="@+id/card_message_other"
                app:layout_constraintLeft_toRightOf="@+id/card_message_other"/>
    </androidx.constraintlayout.widget.ConstraintLayout>


</LinearLayout>

UI Right Message

XML:


// ./app/src/main/res/layout/card_view_right.xml
 
<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"                                                   xmlns:app="http://schemas.android.com/apk/res-auto"                                                   android:layout_width="match_parent"                                                   android:layout_height="wrap_content" 
android:layout_marginEnd="8dp">

    <androidx.cardview.widget.CardView
            android:id="@+id/card_message_me"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="right"
            android:layout_marginBottom="10dp"
            android:foreground="?android:attr/selectableItemBackground"
            app:cardBackgroundColor="@color/purple_500"
            app:cardCornerRadius="10dp"
            app:cardElevation="0dp"
            app:cardPreventCornerOverlap="false"
            app:cardUseCompatPadding="true"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent">

        <include layout="@layout/common_cell"/>

    </androidx.cardview.widget.CardView>

    <TextView
            android:id="@+id/dateText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="12dp"
            android:layout_marginBottom="4dp"
            android:text="10:00"
            app:layout_constraintBottom_toBottomOf="@+id/card_message_me"
            app:layout_constraintRight_toLeftOf="@+id/card_message_me"/>

</androidx.constraintlayout.widget.ConstraintLayout>

UI Additional Color Values

XML:


// ./app/src/main/res/values/colors.xml
 
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!--    ...-->
    <color name="dark_gray">#4F4F4F</color>
    <color name="blue">#186ED3</color>
    <color name="dark_red">#b30000</color>
    <color name="light_gray">#B7B7B7</color>
    <color name="light_gray_2">#eef1f6</color>
</resources>

Apply View Binding

We leverage the Android View Binding feature to be able to reference binding classes for our XML layout. To enable the feature, set the viewBinding build option to true in ./app/build.gradle:

Kotlin Script:


 // ./app/build.gradle

android {
//    ...

    buildFeatures {
        viewBinding = true
    }
//    ...
}

Now it's time to connect the UI with our Kotlin code:

Kotlin:


// ./app/src/main/java/com/chatterbox/myapp/MainActivity.kt

package com.chatterbox.myapp
// ...

class MainActivity : AppCompatActivity() {
    // ...
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // Create room instance
        room = ChatRoom(REGION, ::fetchChatToken).apply {
            // ...
        }

        binding.sendButton.setOnClickListener(::sendButtonClick)
        binding.connectButton.setOnClickListener {connect()}

        setUpChatView()

        updateConnectionState(ChatRoom.State.DISCONNECTED)
    }

    private fun sendMessage(request: SendMessageRequest) {
        lifecycleScope.launch {
           try {
               binding.messageEditText.text.clear()
               room?.awaitSendMessage(request)
           } catch (exception: ChatException) {
               Log.e(TAG, "Message rejected: ${exception.message}")
           } catch (exception: Exception) {
               Log.e(TAG, exception.message ?: "Unknown error occurred")
           }
        }
    }

    private fun sendButtonClick(view: View) {
        val content = binding.messageEditText.text.toString()
        if (content.trim().isEmpty()) {
            return
        }

        val request = SendMessageRequest(content)
        sendMessage(request)
    }
// ...

}

We also add methods to delete messages and disconnect users from the chat, which can be invoked using the chat-message context menu:

Kotlin:


// ./app/src/main/java/com/chatterbox/myapp/MainActivity.kt

package com.chatterbox.myapp
//    ...

class MainActivity : AppCompatActivity() {
//    ...

    private fun deleteMessage(request: DeleteMessageRequest) {
        lifecycleScope.launch {
           try {
               room?.awaitDeleteMessage(request)
           } catch (exception: ChatException) {
               Log.e(TAG, "Delete message rejected: ${exception.message}")
           } catch (exception: Exception) {
               Log.e(TAG, exception.message ?: "Unknown error occurred")
           }
        }
    }

    private fun disconnectUser(request: DisconnectUserRequest) {
        lifecycleScope.launch {
           try {
               room?.awaitDisconnectUser(request)
           } catch (exception: ChatException) {
               Log.e(TAG, "Disconnect user rejected: ${exception.message}")
           } catch (exception: Exception) {
               Log.e(TAG, exception.message ?: "Unknown error occurred")
           }
        }
    }
}

Manage Chat-Message Requests

We need a way to manage our chat-message requests through all their possible states:

Pending — A message was sent to a chat room but is not yet confirmed or rejected.
Confirmed — A message was sent by the chat room to all users (including us).
Rejected — A message was rejected by the chat room with an error object.

We will keep unresolved chat requests and chat messages in a list. The list merits a separate class, which we call ChatEntries.kt:

Kotlin:


// ./app/src/main/java/com/chatterbox/myapp/ChatEntries.kt

package com.chatterbox.myapp

import com.amazonaws.ivs.chat.messaging.entities.ChatMessage
import com.amazonaws.ivs.chat.messaging.requests.SendMessageRequest

sealed class ChatEntry() {
    class Message(val message: ChatMessage) : ChatEntry()
    class PendingRequest(val request: SendMessageRequest) : ChatEntry()
    class FailedRequest(val request: SendMessageRequest) : ChatEntry()
}

class ChatEntries {
    /* This list is kept in sorted order. ChatMessages are sorted by date, while pending and failed requests are kept in their original insertion point. */
    val entries = mutableListOf<ChatEntry>()
    var adapter: ChatListAdapter? = null

    val size get() = entries.size

    /**
     * Insert pending request at the end.
     */
    fun addPendingRequest(request: SendMessageRequest) {
        val insertIndex = entries.size
        entries.add(insertIndex, ChatEntry.PendingRequest(request))
        adapter?.notifyItemInserted(insertIndex)
    }

    /**
     * Insert received message at proper place based on sendTime. This can cause removal of pending requests.
     */
    fun addReceivedMessage(message: ChatMessage) {
        /* Skip if we have already handled that message. */
        val existingIndex = entries.indexOfLast { it is ChatEntry.Message && it.message.id == message.id }
        if (existingIndex != -1) {
            return
        }

        val removeIndex = entries.indexOfLast {
            it is ChatEntry.PendingRequest && it.request.requestId == message.requestId
        }
        if (removeIndex != -1) {
            entries.removeAt(removeIndex)
        }

        val insertIndexRaw = entries.indexOfFirst { it is ChatEntry.Message && it.message.sendTime > message.sendTime }
        val insertIndex = if (insertIndexRaw == -1) entries.size else insertIndexRaw
        entries.add(insertIndex, ChatEntry.Message(message))

        if (removeIndex == -1) {
            adapter?.notifyItemInserted(insertIndex)
        } else if (removeIndex == insertIndex) {
            adapter?.notifyItemChanged(insertIndex)
        } else {
            adapter?.notifyItemRemoved(removeIndex)
            adapter?.notifyItemInserted(insertIndex)
        }
    }

    fun addFailedRequest(request: SendMessageRequest) {
        val removeIndex = entries.indexOfLast {
            it is ChatEntry.PendingRequest && it.request.requestId == request.requestId
        }
        if (removeIndex != -1) {
            entries.removeAt(removeIndex)
            entries.add(removeIndex, ChatEntry.FailedRequest(request))
            adapter?.notifyItemChanged(removeIndex)
        } else {
            val insertIndex = entries.size
            entries.add(insertIndex, ChatEntry.FailedRequest(request))
            adapter?.notifyItemInserted(insertIndex)
        }
    }

    fun removeMessage(messageId: String) {
        val removeIndex = entries.indexOfFirst { it is ChatEntry.Message && it.message.id == messageId }
        entries.removeAt(removeIndex)
        adapter?.notifyItemRemoved(removeIndex)
    }

    fun removeFailedRequest(requestId: String) {
        val removeIndex = entries.indexOfFirst { it is ChatEntry.FailedRequest && it.request.requestId == requestId }
        entries.removeAt(removeIndex)
        adapter?.notifyItemRemoved(removeIndex)
    }

    fun removeAll() {
        entries.clear()
    }
}

To connect our list with the UI, we use an Adapter. For more information, see Binding to Data with AdapterView and Generated binding classes.

Kotlin:


// ./app/src/main/java/com/chatterbox/myapp/ChatListAdapter.kt

package com.chatterbox.myapp

import android.content.Context
import android.graphics.Color
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.LinearLayout
import android.widget.TextView
import androidx.core.content.ContextCompat
import androidx.core.view.isGone
import androidx.recyclerview.widget.RecyclerView
import com.amazonaws.ivs.chat.messaging.requests.DisconnectUserRequest
import java.text.DateFormat


class ChatListAdapter(
    private val entries: ChatEntries,
    private val onDisconnectUser: (request: DisconnectUserRequest) -> Unit,
) :
    RecyclerView.Adapter<ChatListAdapter.ViewHolder>() {
    var context: Context? = null
    var userId: String? = null

    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        val container: LinearLayout = view.findViewById(R.id.layout_container)
        val textView: TextView = view.findViewById(R.id.card_message_me_text_view)
        val failedMark: TextView = view.findViewById(R.id.failed_mark)
        val userNameText: TextView? = view.findViewById(R.id.username_edit_text)
        val dateText: TextView? = view.findViewById(R.id.dateText)
    }

    override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
        if (viewType == 0) {
            val rightView = LayoutInflater.from(viewGroup.context).inflate(R.layout.card_view_right, viewGroup, false)
            return ViewHolder(rightView)
        }
        val leftView = LayoutInflater.from(viewGroup.context).inflate(R.layout.card_view_left, viewGroup, false)
        return ViewHolder(leftView)
    }

    override fun getItemViewType(position: Int): Int {
        // Int 0 indicates to my message while Int 1 to other message
        val chatMessage = entries.entries[position]
        return if (chatMessage is ChatEntry.Message && chatMessage.message.sender.userId != userId) 1 else 0
    }

    override fun onBindViewHolder(viewHolder: ViewHolder, position: Int) {
        return when (val entry = entries.entries[position]) {
            is ChatEntry.Message -> {
                viewHolder.textView.text = entry.message.content

                val bgColor = if (entry.message.sender.userId == userId) {
                    R.color.purple_500
                } else {
                    R.color.light_gray_2
                }
                viewHolder.container.setBackgroundColor(ContextCompat.getColor(context!!, bgColor))

                if (entry.message.sender.userId != userId) {
                    viewHolder.textView.setTextColor(Color.parseColor("#000000"))
                }

                viewHolder.failedMark.isGone = true

                viewHolder.itemView.setOnCreateContextMenuListener { menu, _, _ ->
                    menu.add("Kick out").setOnMenuItemClickListener {
                        val request = DisconnectUserRequest(entry.message.sender.userId, "Some reason")
                        onDisconnectUser(request)
                        true
                    }
                }

                viewHolder.userNameText?.text = entry.message.sender.userId
                viewHolder.dateText?.text =
                    DateFormat.getTimeInstance(DateFormat.SHORT).format(entry.message.sendTime)
            }

            is ChatEntry.PendingRequest -> {
                viewHolder.container.setBackgroundColor(ContextCompat.getColor(context!!, R.color.light_gray))
                viewHolder.textView.text = entry.request.content
                viewHolder.failedMark.isGone = true
                viewHolder.itemView.setOnCreateContextMenuListener(null)
                viewHolder.dateText?.text = "Sending"
            }

            is ChatEntry.FailedRequest -> {
                viewHolder.textView.text = entry.request.content
                viewHolder.container.setBackgroundColor(ContextCompat.getColor(context!!, R.color.dark_red))
                viewHolder.failedMark.isGone = false
                viewHolder.dateText?.text = "Failed"
            }
        }
    }

    override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
        super.onAttachedToRecyclerView(recyclerView)
        context = recyclerView.context
    }

    override fun getItemCount() = entries.entries.size
}

Final Steps

It is time to hook up our new adapter, binding ChatEntries class to MainActivity:

Kotlin:


// ./app/src/main/java/com/chatterbox/myapp/MainActivity.kt

package com.chatterbox.myapp
// ...

import com.chatterbox.myapp.databinding.ActivityMainBinding
import com.chatterbox.myapp.ChatListAdapter
import com.chatterbox.myapp.ChatEntries

class MainActivity : AppCompatActivity() {
    // ...
    private var entries = ChatEntries()
    private lateinit var adapter: ChatListAdapter

    // ...

    private fun setUpChatView() {
        adapter = ChatListAdapter(entries, ::disconnectUser)
        entries.adapter = adapter

        val recyclerViewLayoutManager = LinearLayoutManager(this@MainActivity, LinearLayoutManager.VERTICAL, false)
        binding.recyclerView.layoutManager = recyclerViewLayoutManager
        binding.recyclerView.adapter = adapter

        binding.sendButton.setOnClickListener(::sendButtonClick)
        binding.messageEditText.setOnEditorActionListener { _, _, event ->
            val isEnterDown = (event.action == KeyEvent.ACTION_DOWN) && (event.keyCode == KeyEvent.KEYCODE_ENTER)
            if (!isEnterDown) {
                return@setOnEditorActionListener false
            }

            sendButtonClick(binding.sendButton)
            return@setOnEditorActionListener true
        }
    }
}

As we already have a class responsible for keeping track of our chat requests (ChatEntries), we are ready to implement code for manipulating entries in roomListener. We will update entries and connectionState accordingly to the event we are responding to:

Kotlin:


// ./app/src/main/java/com/chatterbox/myapp/MainActivity.kt

package com.chatterbox.myapp
// ...

class MainActivity : AppCompatActivity() {
// ...


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // Create room instance
        room = ChatRoom(REGION, ::fetchChatToken).apply {
            lifecycleScope.launch {
                stateChanges().collect { state ->
                    Log.d(TAG, "state change to $state")
                    updateConnectionState(state)
                    if (state == ChatRoom.State.DISCONNECTED) {
                       entries.removeAll()
                    }
                }
            }

            lifecycleScope.launch {
                receivedMessages().collect { message ->
                    Log.d(TAG, "messageReceived $message")
                    entries.addReceivedMessage(message)
                }
            }

            lifecycleScope.launch {
                receivedEvents().collect { event ->
                    Log.d(TAG, "eventReceived $event")
                }
            }

            lifecycleScope.launch {
                deletedMessages().collect { event ->
                    Log.d(TAG, "messageDeleted $event")
                    entries.removeMessage(event.messageId)
                }
            }

            lifecycleScope.launch {
                disconnectedUsers().collect { event ->
                    Log.d(TAG, "userDisconnected $event")
                }
            }
        }

        binding.sendButton.setOnClickListener(::sendButtonClick)
        binding.connectButton.setOnClickListener {connect()}

        setUpChatView()

        updateConnectionState(ChatRoom.State.DISCONNECTED)
    }

// ...

}

Now you should be able to run your application! (See Build and run your app.) Remember to have your backend server running when using the app. You can spin it up from the terminal at the root of our project with this command: ./gradlew :auth-server:run or by executing the auth-server:run Gradle task directly from Android Studio.

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Document Conventions

Kotlin Coroutines Tutorial Part 1: Chat Rooms

iOS Guide