[안드로이드/Android] MVVM 이벤트 처리

class SingleLiveEvent<T> : MutableLiveData<T>() {
    private val pending = AtomicBoolean(false)

    @MainThread
    override fun observe(owner: LifecycleOwner, observer: Observer<in T>) {
        if (hasActiveObservers()) {
            Log.w(TAG, "Multiple observers registered but only one will be notified of changes.")
        }
        // Observe the internal MutableLiveData
        super.observe(owner, Observer { t ->
            if (pending.compareAndSet(true, false)) {
                observer.onChanged(t)
            }
        })
    }

    @MainThread
    override fun setValue(t: T?) {
        pending.set(true)
        super.setValue(t)
    }

    @MainThread
    fun call() {
        value = null
    }
    companion object {
        private val TAG = "SingleLiveEvent"
    }
}

ViewModel

class RegisterEventsViewModel : ViewModel() {
	val startHomeActivityClickEvent = SingleLiveEvent<Any>()

	fun onCancelClick() {
        startHomeActivityClickEvent.call()
    }
}

Activity

class RegisterEventsActivity: AppCompatActivity() {

	override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.register_events)
        registerModel = RegisterEventsViewModel()
        binding.registerViewModel = registerModel
        binding.lifecycleOwner = this

        setupButtons()
    }
private fun setupButtons() {
        registerModel.startHomeActivityClickEvent.observe(
            this, {
                val intent = Intent(this, MainActivity::class.java)
                startActivity(intent)
            }
        )
    }
}

register_events.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>
    <data>
        <variable
            name="registerViewModel"
            type="org.inu.events.viewmodel.RegisterEventsViewModel" />
    </data>

...

<androidx.appcompat.widget.AppCompatButton
       android:id="@+id/button_cancel"
       android:layout_width="0dp"
       android:layout_height="52dp"
       android:background="@drawable/drawable_btn_background"
       android:text="@string/text_cancel"
       android:textColor="@color/primary"
       android:textFontWeight="400"
       android:textSize="15sp"
       android:onClick="@{ () -> registerViewModel.onCancelClick()}"
       app:layout_constraintBottom_toBottomOf="parent"
       app:layout_constraintEnd_toStartOf="@+id/button_next"
       app:layout_constraintStart_toStartOf="parent" />

기록용으로 다음 코드는

https://algosketch.tistory.com/146

를 참조했습니다.