SingleLiveData Sample #Kotlin #sample #LiveData

SingleLiveData.kt

public class SingleLiveData<T> : MutableLiveData<T> {

    private val pending = AtomicBoolean(false)

    @MainThread
    override fun observe(owner: LifecycleOwner, observer: Observer<T>) {
        super.observe(owner, object : Observer<T>() {
            override fun onChanged(t: T?) {
                // compareAndSet(expect, update)
                //  here if `true` then set to false
                if (pending.compareAndSet(true, false)) {
                    observe.onChanged(t)
                }
            }
        })
    }

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