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SingleLiveEvent.kt
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SingleLiveEvent.kt
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package com.applogist.helpers
import android.util.Log
import androidx.annotation.MainThread
import androidx.annotation.Nullable
import androidx.lifecycle.LifecycleOwner
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.Observer
import java.util.concurrent.atomic.AtomicBoolean
/**
* Single Live Event class
*/
class SingleLiveEvent<T> : MutableLiveData<T>() {
private val mPending = AtomicBoolean(false)
@MainThread
override fun observe(owner: LifecycleOwner, observer: Observer<in T>) {
if (hasActiveObservers()) {
Log.w("SingleLiveEvent", "Multiple observers registered but only one will be notified of changes.")
}
// Observe the internal MutableLiveData
super.observe(owner, Observer<T> { t ->
if (mPending.compareAndSet(true, false)) {
observer.onChanged(t)
}
})
}
@MainThread
override fun setValue(@Nullable t: T?) {
mPending.set(true)
super.setValue(t)
}
/**
* Used for cases where T is Void, to make calls cleaner.
*/
@MainThread
fun call() {
value = null
}
}