package com.doumee.lib_coremodel.base.livedata;
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import androidx.annotation.MainThread;
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import androidx.annotation.Nullable;
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import androidx.lifecycle.LifecycleOwner;
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import androidx.lifecycle.MutableLiveData;
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import androidx.lifecycle.Observer;
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import java.util.concurrent.atomic.AtomicBoolean;
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import timber.log.Timber;
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/**
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* 提供观察单个对象{@link T}事件
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* @see <a href="https://github.com/googlesamples/android-architecture/blob/6419d4c523b67d020120fc400ed5a7372e5615f2/todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/SingleLiveEvent.java">google sample</a>
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* @author <a href="mailto:jenly1314@gmail.com">Jenly</a>
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*/
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public class SingleLiveEvent<T> extends MutableLiveData<T> {
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private final AtomicBoolean mPending = new AtomicBoolean(false);
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@MainThread
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public void observe(LifecycleOwner owner, final Observer<? super T> observer) {
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if (hasActiveObservers()) {
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Timber.w("Multiple observers registered but only one will be notified of changes.");
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}
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// Observe the internal MutableLiveData
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super.observe(owner, new Observer<T>() {
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@Override
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public void onChanged(@Nullable T t) {
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if (mPending.compareAndSet(true, false)) {
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observer.onChanged(t);
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}
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}
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});
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}
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@MainThread
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public void setValue(@Nullable T t) {
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mPending.set(true);
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super.setValue(t);
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}
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/**
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* Used for cases where T is Void, to make calls cleaner.
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*/
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@MainThread
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public void call() {
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setValue(null);
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}
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}
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