override fun onCreate()

in build-android/app/src/main/java/com/google/firebase/codelab/friendlychat/MainActivity.kt [55:124]
44 lines of code
3 McCabe index (conditional complexity)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // This codelab uses View Binding
        // See: https://developer.android.com/topic/libraries/view-binding
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // When running in debug mode, connect to the Firebase Emulator Suite
        // "10.0.2.2" is a special value which allows the Android emulator to
        // connect to "localhost" on the host computer. The port values are
        // defined in the firebase.json file.
        if (BuildConfig.DEBUG) {
            Firebase.database.useEmulator("10.0.2.2", 9000)
            Firebase.auth.useEmulator("10.0.2.2", 9099)
            Firebase.storage.useEmulator("10.0.2.2", 9199)
        }

        // Initialize Firebase Auth and check if the user is signed in
        auth = Firebase.auth
        if (auth.currentUser == null) {
            // Not signed in, launch the Sign In activity
            startActivity(Intent(this, SignInActivity::class.java))
            finish()
            return
        }

        // Initialize Realtime Database
        db = Firebase.database
        val messagesRef = db.reference.child(MESSAGES_CHILD)

        // The FirebaseRecyclerAdapter class and options come from the FirebaseUI library
        // See: https://github.com/firebase/FirebaseUI-Android
        val options = FirebaseRecyclerOptions.Builder<FriendlyMessage>()
            .setQuery(messagesRef, FriendlyMessage::class.java)
            .build()
        adapter = FriendlyMessageAdapter(options, getUserName())
        binding.progressBar.visibility = ProgressBar.INVISIBLE
        manager = LinearLayoutManager(this)
        manager.stackFromEnd = true
        binding.messageRecyclerView.layoutManager = manager
        binding.messageRecyclerView.adapter = adapter

        // Scroll down when a new message arrives
        // See MyScrollToBottomObserver for details
        adapter.registerAdapterDataObserver(
            MyScrollToBottomObserver(binding.messageRecyclerView, adapter, manager)
        )

        // Disable the send button when there's no text in the input field
        // See MyButtonObserver for details
        binding.messageEditText.addTextChangedListener(MyButtonObserver(binding.sendButton))

        // When the send button is clicked, send a text message
        binding.sendButton.setOnClickListener {
            val friendlyMessage = FriendlyMessage(
                binding.messageEditText.text.toString(),
                getUserName(),
                getPhotoUrl(),
                null
            )
            db.reference.child(MESSAGES_CHILD).push().setValue(friendlyMessage)
            binding.messageEditText.setText("")
        }

        // When the image button is clicked, launch the image picker
        binding.addMessageImageView.setOnClickListener {
            openDocument.launch(arrayOf("image/*"))
        }
    }