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Kaushik Gopal
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refactor: use Subject for searching demo
1 parent 87c4492 commit 7e66871

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+221
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6 files changed

+221
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‎app/src/main/java/com/morihacky/android/rxjava/BehaviorSubjectSearchEmitterFragment.java‎

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package com.morihacky.android.rxjava;
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import android.content.Context;
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import android.os.Bundle;
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import android.os.Handler;
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import android.os.Looper;
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import android.support.annotation.Nullable;
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import android.support.v4.app.Fragment;
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import android.view.LayoutInflater;
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import android.view.View;
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import android.view.ViewGroup;
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import android.widget.ArrayAdapter;
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import android.widget.ListView;
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import com.morihacky.android.rxjava.app.R;
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import java.util.ArrayList;
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import java.util.List;
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import butterknife.ButterKnife;
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import butterknife.InjectView;
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import butterknife.OnTextChanged;
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import rx.Observable;
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import rx.Observer;
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import rx.Subscriber;
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import rx.Subscription;
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import rx.android.observables.AndroidObservable;
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import rx.android.schedulers.AndroidSchedulers;
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import rx.schedulers.Schedulers;
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import rx.subjects.BehaviorSubject;
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import timber.log.Timber;
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/**
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* The reason we use a Subject for tracking the search query is because it emits observables.
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* Because a Subject subscribes to an Observable, it will trigger that Observable to begin emitting items
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* (if that Observable is "cold" — that is, if it waits for a subscription before it begins to emit items).
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* This can have the effect of making the resulting Subject a "hot" Observable variant of the original "cold" Observable.
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*
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* This allows us to create the subject and subscription one time onActivity creation. Subsequently
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* we send in Observables to the Subject's subscriber onTextChanged
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*
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* Otherwise we would have to create the subscription onTextChanged every single time, which is
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* wasteful (not really since we anyway unsubscribe at the end).
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* less-elegant (as a concept for sure, but not for simplicity vs. the 3 step basic subscription creation)
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* doesn't allow us to debounce/throttle/sample ?
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*
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*/
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public class BehaviorSubjectSearchEmitterFragment
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extends Fragment {
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@InjectView(R.id.list_threading_log) ListView _logsList;
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private LogAdapter _adapter;
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private List<String> _logs;
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private Subscription _subscription;
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private BehaviorSubject<Observable<String>> _searchTextEmitterSubject;
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@Override
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public void onActivityCreated(@Nullable Bundle savedInstanceState) {
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super.onActivityCreated(savedInstanceState);
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_setupLogger();
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_searchTextEmitterSubject = BehaviorSubject.create(Observable.<String>empty());
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_subscription = AndroidObservable.bindFragment(BehaviorSubjectSearchEmitterFragment.this,
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Observable.switchOnNext(_searchTextEmitterSubject))
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.subscribeOn(Schedulers.io())
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.observeOn(AndroidSchedulers.mainThread())
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.subscribe(_getSearchObserver());
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// .debounce(400, TimeUnit.MILLISECONDS, Schedulers.io())
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}
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@OnTextChanged(R.id.input_txt_subject)
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public void onTextEntered(CharSequence charsEntered) {
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Timber.d("---------- text entered %s", charsEntered);
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_searchTextEmitterSubject.onNext(_getASearchObservableFor(charsEntered.toString()));
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}
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// -----------------------------------------------------------------------------------
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// Main Rx entities
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private Observable<String> _getASearchObservableFor(final String searchText) {
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return Observable.create(new Observable.OnSubscribe<String>() {
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@Override
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public void call(Subscriber<? super String> subscriber) {
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subscriber.onNext(searchText);
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subscriber.onCompleted();
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}
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});
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}
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private Observer<String> _getSearchObserver() {
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return new Observer<String>() {
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@Override
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public void onCompleted() {
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Timber.d("--------- onComplete");
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}
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@Override
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public void onError(Throwable e) {
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Timber.e(e, "--------- Woops on error!");
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_log(String.format("Dang error. check your logs"));
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}
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@Override
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public void onNext(String searchText) {
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Timber.d("--------- onNext");
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_log(String.format("You searched for %s", searchText));
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}
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};
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}
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@Override
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public void onDestroy() {
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super.onDestroy();
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_subscription.unsubscribe();
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}
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// -----------------------------------------------------------------------------------
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// Method that help wiring up the example (irrelevant to RxJava)
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@Override
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public View onCreateView(LayoutInflater inflater,
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@Nullable ViewGroup container,
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@Nullable Bundle savedInstanceState) {
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View layout = inflater.inflate(R.layout.fragment_subject, container, false);
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ButterKnife.inject(this, layout);
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return layout;
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}
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private void _setupLogger() {
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_logs = new ArrayList<String>();
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_adapter = new LogAdapter(getActivity(), new ArrayList<String>());
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_logsList.setAdapter(_adapter);
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}
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private void _log(String logMsg) {
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if (_isCurrentlyOnMainThread()) {
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_logs.add(0, logMsg + " (main thread) ");
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_adapter.clear();
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_adapter.addAll(_logs);
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} else {
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_logs.add(0, logMsg + " (NOT main thread) ");
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// You can only do below stuff on main thread.
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new Handler(Looper.getMainLooper()).post(new Runnable() {
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@Override
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public void run() {
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_adapter.clear();
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_adapter.addAll(_logs);
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}
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});
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}
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}
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private boolean _isCurrentlyOnMainThread() {
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return Looper.myLooper() == Looper.getMainLooper();
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}
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private class LogAdapter
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extends ArrayAdapter<String> {
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public LogAdapter(Context context, List<String> logs) {
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super(context, R.layout.item_log, R.id.item_log, logs);
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}
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}
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}

‎app/src/main/java/com/morihacky/android/rxjava/MainActivity.java‎

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getSupportFragmentManager().beginTransaction()
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.addToBackStack(this.toString())
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// .replace(R.id.activity_main, new MainFragment(), this.toString())
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.replace(R.id.activity_main, new BufferDemoFragment(), this.toString())
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.replace(R.id.activity_main, new BehaviorSubjectSearchEmitterFragment(), this.toString())
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.commit();
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}
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}

‎app/src/main/java/com/morihacky/android/rxjava/MainFragment.java‎

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.commit();
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}
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@OnClick(R.id.btn_demo_buffer)
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public void demoBuffer() {
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getActivity().getSupportFragmentManager()
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.commit();
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}
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@OnClick(R.id.btn_demo_subject)
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public void demoThrottling() {
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getActivity().getSupportFragmentManager()
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.beginTransaction()
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.addToBackStack(this.toString())
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.replace(R.id.activity_main,
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new BehaviorSubjectSearchEmitterFragment(),
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this.toString())
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.commit();
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}
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}

‎app/src/main/res/layout/fragment_main.xml‎

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android:text="@string/btn_demo_buffer"/>
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<Button
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android:id="@+id/btn_demo_throttle"
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android:id="@+id/btn_demo_subject"
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android:layout_height="wrap_content"
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android:layout_width="wrap_content"
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android:text="@string/btn_demo_throttle"/>
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android:text="@string/btn_demo_subject"/>
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</LinearLayout>

‎app/src/main/res/layout/fragment_subject.xml‎

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<?xml version="1.0" encoding="utf-8"?>
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<LinearLayout
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android:orientation="vertical"
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android:layout_height="match_parent"
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android:layout_width="match_parent"
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xmlns:android="http://schemas.android.com/apk/res/android">
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<TextView
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android:layout_height="wrap_content"
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android:layout_width="match_parent"
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android:padding="10dp"
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android:gravity="center"
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android:text="@string/msg_demo_subject"/>
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<EditText
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android:id="@+id/input_txt_subject"
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android:layout_height="wrap_content"
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android:layout_width="match_parent"
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android:textSize="16sp"
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android:hint="Enter some search text"/>
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<ListView
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android:id="@+id/list_threading_log"
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android:layout_height="match_parent"
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android:layout_width="match_parent"/>
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</LinearLayout>

‎app/src/main/res/values/strings.xml‎

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<string name="msg_demo_buffer">This is a demo of how events can be accumulated using the "buffer" operation. Tap the button below repetitively and you will notice in the logs that button taps are collected over a span of 2s and printed below.</string>
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<string name="msg_demo_concurrency_schedulers">This is a demo of how long running operations can be offloaded to a background thread. After the operation is done, we resume back on the main thread. All using RxJava! \n\n To really see this shine. Hit the button multiple times and see how the button click which is a ui operation is never blocked because the long operation only runs in the background</string>
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<string name="msg_demo_subject">As you type in the input box, it will not shoot out log messages at every single input character change, but rather only pick the lastly emitted event (i.e. input) and log that. \n\nThis is the debounce/throttleWithTimeout method in RxJava.</string>
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<string name="btn_demo_schedulers">bg work (schedulers &amp; concurrency)</string>
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<string name="btn_demo_buffer">accumulate calls (buffer)</string>
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<string name="btn_demo_throttle">instant search (throttle)</string>
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<string name="btn_demo_subject">instant search (subject throttling?)</string>
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</resources>

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