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/**
* Copyright 2013 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package rx;
import static org.junit.Assert.*;
import static org.mockito.Matchers.*;
import static org.mockito.Mockito.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import org.junit.Before;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import rx.observables.BlockingObservable;
import rx.observables.ConnectableObservable;
import rx.observables.GroupedObservable;
import rx.operators.AtomicObservableSubscription;
import rx.operators.AtomicObserver;
import rx.operators.OperationAll;
import rx.operators.OperationCache;
import rx.operators.OperationConcat;
import rx.operators.OperationDefer;
import rx.operators.OperationDematerialize;
import rx.operators.OperationFilter;
import rx.operators.OperationFinally;
import rx.operators.OperationGroupBy;
import rx.operators.OperationMap;
import rx.operators.OperationMaterialize;
import rx.operators.OperationMerge;
import rx.operators.OperationMergeDelayError;
import rx.operators.OperationMulticast;
import rx.operators.OperationObserveOn;
import rx.operators.OperationOnErrorResumeNextViaFunction;
import rx.operators.OperationOnErrorResumeNextViaObservable;
import rx.operators.OperationOnErrorReturn;
import rx.operators.OperationSample;
import rx.operators.OperationScan;
import rx.operators.OperationSkip;
import rx.operators.OperationSubscribeOn;
import rx.operators.OperationSwitch;
import rx.operators.OperationSynchronize;
import rx.operators.OperationTake;
import rx.operators.OperationTakeLast;
import rx.operators.OperationTakeUntil;
import rx.operators.OperationTakeWhile;
import rx.operators.OperationTimestamp;
import rx.operators.OperationToObservableFuture;
import rx.operators.OperationToObservableIterable;
import rx.operators.OperationToObservableList;
import rx.operators.OperationToObservableSortedList;
import rx.operators.OperationWhere;
import rx.operators.OperationZip;
import rx.plugins.RxJavaErrorHandler;
import rx.plugins.RxJavaObservableExecutionHook;
import rx.plugins.RxJavaPlugins;
import rx.subjects.PublishSubject;
import rx.subjects.ReplaySubject;
import rx.subjects.Subject;
import rx.subscriptions.BooleanSubscription;
import rx.subscriptions.Subscriptions;
import rx.util.OnErrorNotImplementedException;
import rx.util.Range;
import rx.util.Timestamped;
import rx.util.functions.Action0;
import rx.util.functions.Action1;
import rx.util.functions.Func0;
import rx.util.functions.Func1;
import rx.util.functions.Func2;
import rx.util.functions.Func3;
import rx.util.functions.Func4;
import rx.util.functions.FuncN;
import rx.util.functions.Function;
import rx.util.functions.FunctionLanguageAdaptor;
import rx.util.functions.Functions;
/**
* The Observable interface that implements the Reactive Pattern.
* <p>
* This interface provides overloaded methods for subscribing as well as delegate methods to the
* various operators.
* <p>
* The documentation for this interface makes use of marble diagrams. The following legend explains
* these diagrams:
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/legend.png">
* <p>
* For more information see the <a href="https://github.com/Netflix/RxJava/wiki/Observable">RxJava
* Wiki</a>
*
* @param <T>
*/
public class Observable<T> {
//TODO use a consistent parameter naming scheme (for example: for all operators that modify a source Observable, the parameter representing that source Observable should have the same name, e.g. "source" -- currently such parameters are named any of "sequence", "that", "source", "items", or "observable")
private final static RxJavaObservableExecutionHook hook = RxJavaPlugins.getInstance().getObservableExecutionHook();
private final Func1<Observer<T>, Subscription> onSubscribe;
/**
* Observable with Function to execute when subscribed to.
* <p>
* NOTE: Use {@link #create(Func1)} to create an Observable instead of this method unless you
* specifically have a need for inheritance.
*
* @param onSubscribe
* {@link Func1} to be executed when {@link #subscribe(Observer)} is called.
*/
protected Observable(Func1<Observer<T>, Subscription> onSubscribe) {
this.onSubscribe = onSubscribe;
}
protected Observable() {
this(null);
//TODO should this be made private to prevent it? It really serves no good purpose and only confuses things. Unit tests are incorrectly using it today
}
/**
* An {@link Observer} must call an Observable's <code>subscribe</code> method in order to
* receive items and notifications from the Observable. A typical implementation of
* <code>subscribe</code> does the following:
* <p>
* It stores a reference to the Observer in a collection object, such as a
* <code>List<T></code> object.
* <p>
* It returns a reference to the {@link Subscription} interface. This enables Observers to
* unsubscribe, that is, to stop receiving items and notifications before the Observable stops
* sending them, which also invokes the Observer's {@link Observer#onCompleted onCompleted}
* method.
* <p>
* An <code>Observable<T></code> instance is responsible for accepting all subscriptions
* and notifying all Observers. Unless the documentation for a particular
* <code>Observable<T></code> implementation indicates otherwise, Observers should make no
* assumptions about the order in which multiple Observers will receive their notifications.
* <p>
* For more information see the
* <a href="https://github.com/Netflix/RxJava/wiki/Observable">RxJava Wiki</a>
*
* @param observer
* @return a {@link Subscription} reference with which the Observer can stop receiving items
* before the Observable has finished sending them
* @throws IllegalArgumentException
* if the {@link Observer} provided as the argument to <code>subscribe()</code> is
* <code>null</code>
*/
public Subscription subscribe(Observer<T> observer) {
// allow the hook to intercept and/or decorate
Func1<Observer<T>, Subscription> onSubscribeFunction = hook.onSubscribeStart(this, onSubscribe);
// validate and proceed
if (observer == null) {
throw new IllegalArgumentException("observer can not be null");
}
if (onSubscribeFunction == null) {
throw new IllegalStateException("onSubscribe function can not be null.");
// the subscribe function can also be overridden but generally that's not the appropriate approach so I won't mention that in the exception
}
try {
/**
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
if (isInternalImplementation(observer)) {
Subscription s = onSubscribeFunction.call(observer);
if (s == null) {
// this generally shouldn't be the case on a 'trusted' onSubscribe but in case it happens
// we want to gracefully handle it the same as AtomicObservableSubscription does
return hook.onSubscribeReturn(this, Subscriptions.empty());
} else {
return hook.onSubscribeReturn(this, s);
}
} else {
AtomicObservableSubscription subscription = new AtomicObservableSubscription();
subscription.wrap(onSubscribeFunction.call(new AtomicObserver<T>(subscription, observer)));
return hook.onSubscribeReturn(this, subscription);
}
} catch (OnErrorNotImplementedException e) {
// special handling when onError is not implemented ... we just rethrow
throw e;
} catch (Exception e) {
// if an unhandled error occurs executing the onSubscribe we will propagate it
try {
observer.onError(hook.onSubscribeError(this, e));
} catch (OnErrorNotImplementedException e2) {
// special handling when onError is not implemented ... we just rethrow
throw e2;
} catch (Exception e2) {
// if this happens it means the onError itself failed (perhaps an invalid function implementation)
// so we are unable to propagate the error correctly and will just throw
RuntimeException r = new RuntimeException("Error occurred attempting to subscribe [" + e.getMessage() + "] and then again while trying to pass to onError.", e2);
hook.onSubscribeError(this, r);
throw r;
}
return Subscriptions.empty();
}
}
/**
* An {@link Observer} must call an Observable's <code>subscribe</code> method in order to
* receive items and notifications from the Observable. A typical implementation of
* <code>subscribe</code> method does the following:
* <p>
* It stores a reference to the Observer in a collection object, such as a
* <code>List<T></code> object.
* <p>
* It returns a reference to the {@link Subscription} interface. This enables Observers to
* unsubscribe, that is, to stop receiving items and notifications before the Observable stops
* sending them, which also invokes the Observer's {@link Observer#onCompleted onCompleted}
* method.
* <p>
* An <code>Observable<T></code> instance is responsible for accepting all subscriptions
* and notifying all Observers. Unless the documentation for a particular
* <code>Observable<T></code> implementation indicates otherwise, Observers should make no
* assumptions about the order in which multiple Observers will receive their notifications.
* <p>
* For more information see the
* <a href="https://github.com/Netflix/RxJava/wiki/Observable">RxJava Wiki</a>
*
* @param observer
* @param scheduler
* the {@link Scheduler} on which Observers subscribe to the Observable
* @return a {@link Subscription} reference with which Observers can stop receiving items and
* notifications before the Observable has finished sending them
* @throws IllegalArgumentException
* if an argument to <code>subscribe()</code> is <code>null</code>
*/
public Subscription subscribe(Observer<T> observer, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(observer);
}
/**
* Used for protecting against errors being thrown from Observer implementations and ensuring onNext/onError/onCompleted contract compliance.
* <p>
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
private Subscription protectivelyWrapAndSubscribe(Observer<T> o) {
AtomicObservableSubscription subscription = new AtomicObservableSubscription();
return subscription.wrap(subscribe(new AtomicObserver<T>(subscription, o)));
}
@SuppressWarnings({ "rawtypes", "unchecked" })
public Subscription subscribe(final Map<String, Object> callbacks) {
if (callbacks == null) {
throw new RuntimeException("callbacks map can not be null");
}
Object _onNext = callbacks.get("onNext");
if (_onNext == null) {
throw new RuntimeException("'onNext' key must contain an implementation");
}
// lookup and memoize onNext
final FuncN onNext = Functions.from(_onNext);
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer() {
@Override
public void onCompleted() {
Object onComplete = callbacks.get("onCompleted");
if (onComplete != null) {
Functions.from(onComplete).call();
}
}
@Override
public void onError(Exception e) {
handleError(e);
Object onError = callbacks.get("onError");
if (onError != null) {
Functions.from(onError).call(e);
} else {
throw new OnErrorNotImplementedException(e);
}
}
@Override
public void onNext(Object args) {
onNext.call(args);
}
});
}
public Subscription subscribe(final Map<String, Object> callbacks, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(callbacks);
}
@SuppressWarnings({ "rawtypes", "unchecked" })
public Subscription subscribe(final Object o) {
if (o instanceof Observer) {
// in case a dynamic language is not correctly handling the overloaded methods and we receive an Observer just forward to the correct method.
return subscribe((Observer) o);
}
if (o == null) {
throw new IllegalArgumentException("onNext can not be null");
}
// lookup and memoize onNext
final FuncN onNext = Functions.from(o);
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer() {
@Override
public void onCompleted() {
// do nothing
}
@Override
public void onError(Exception e) {
handleError(e);
throw new OnErrorNotImplementedException(e);
}
@Override
public void onNext(Object args) {
onNext.call(args);
}
});
}
public Subscription subscribe(final Object o, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(o);
}
public Subscription subscribe(final Action1<T> onNext) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer<T>() {
@Override
public void onCompleted() {
// do nothing
}
@Override
public void onError(Exception e) {
handleError(e);
throw new OnErrorNotImplementedException(e);
}
@Override
public void onNext(T args) {
onNext.call(args);
}
});
}
public Subscription subscribe(final Action1<T> onNext, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(onNext);
}
@SuppressWarnings({ "rawtypes", "unchecked" })
public Subscription subscribe(final Object onNext, final Object onError) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
if (onError == null) {
throw new IllegalArgumentException("onError can not be null");
}
// lookup and memoize onNext
final FuncN onNextFunction = Functions.from(onNext);
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer() {
@Override
public void onCompleted() {
// do nothing
}
@Override
public void onError(Exception e) {
handleError(e);
Functions.from(onError).call(e);
}
@Override
public void onNext(Object args) {
onNextFunction.call(args);
}
});
}
public Subscription subscribe(final Object onNext, final Object onError, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(onNext, onError);
}
public Subscription subscribe(final Action1<T> onNext, final Action1<Exception> onError) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
if (onError == null) {
throw new IllegalArgumentException("onError can not be null");
}
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer<T>() {
@Override
public void onCompleted() {
// do nothing
}
@Override
public void onError(Exception e) {
handleError(e);
onError.call(e);
}
@Override
public void onNext(T args) {
onNext.call(args);
}
});
}
public Subscription subscribe(final Action1<T> onNext, final Action1<Exception> onError, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(onNext, onError);
}
@SuppressWarnings({ "rawtypes", "unchecked" })
public Subscription subscribe(final Object onNext, final Object onError, final Object onComplete) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
if (onError == null) {
throw new IllegalArgumentException("onError can not be null");
}
if (onComplete == null) {
throw new IllegalArgumentException("onComplete can not be null");
}
// lookup and memoize onNext
final FuncN onNextFunction = Functions.from(onNext);
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer() {
@Override
public void onCompleted() {
Functions.from(onComplete).call();
}
@Override
public void onError(Exception e) {
handleError(e);
Functions.from(onError).call(e);
}
@Override
public void onNext(Object args) {
onNextFunction.call(args);
}
});
}
public Subscription subscribe(final Object onNext, final Object onError, final Object onComplete, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(onNext, onError, onComplete);
}
public Subscription subscribe(final Action1<T> onNext, final Action1<Exception> onError, final Action0 onComplete) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
if (onError == null) {
throw new IllegalArgumentException("onError can not be null");
}
if (onComplete == null) {
throw new IllegalArgumentException("onComplete can not be null");
}
/**
* Wrapping since raw functions provided by the user are being invoked.
*
* See https://github.com/Netflix/RxJava/issues/216 for discussion on "Guideline 6.4: Protect calls to user code from within an operator"
*/
return protectivelyWrapAndSubscribe(new Observer<T>() {
@Override
public void onCompleted() {
onComplete.call();
}
@Override
public void onError(Exception e) {
handleError(e);
onError.call(e);
}
@Override
public void onNext(T args) {
onNext.call(args);
}
});
}
public Subscription subscribe(final Action1<T> onNext, final Action1<Exception> onError, final Action0 onComplete, Scheduler scheduler) {
return subscribeOn(scheduler).subscribe(onNext, onError, onComplete);
}
/**
* Returns a {@link ConnectableObservable} that upon connection causes the source Observable to
* push results into the specified subject.
*
* @param subject
* the {@link Subject} for the {@link ConnectableObservable} to push source items
* into
* @param <R>
* result type
* @return a {@link ConnectableObservable} that upon connection causes the source Observable to
* push results into the specified {@link Subject}
*/
public <R> ConnectableObservable<R> multicast(Subject<T, R> subject) {
return multicast(this, subject);
}
/**
* Allow the {@link RxJavaErrorHandler} to receive the exception from onError.
*
* @param e
*/
private void handleError(Exception e) {
// onError should be rare so we'll only fetch when needed
RxJavaPlugins.getInstance().getErrorHandler().handleError(e);
}
/**
* An Observable that never sends any information to an {@link Observer}.
*
* This Observable is useful primarily for testing purposes.
*
* @param <T>
* the type of item emitted by the Observable
*/
private static class NeverObservable<T> extends Observable<T> {
public NeverObservable() {
super(new Func1<Observer<T>, Subscription>() {
@Override
public Subscription call(Observer<T> t1) {
return Subscriptions.empty();
}
});
}
}
/**
* an Observable that invokes {@link Observer#onError onError} when the {@link Observer}
* subscribes to it.
*
* @param <T>
* the type of item emitted by the Observable
*/
private static class ThrowObservable<T> extends Observable<T> {
public ThrowObservable(final Exception exception) {
super(new Func1<Observer<T>, Subscription>() {
/**
* Accepts an {@link Observer} and calls its {@link Observer#onError onError} method.
*
* @param observer
* an {@link Observer} of this Observable
* @return a reference to the subscription
*/
@Override
public Subscription call(Observer<T> observer) {
observer.onError(exception);
return Subscriptions.empty();
}
});
}
}
/**
* Creates an Observable that will execute the given function when an {@link Observer}
* subscribes to it.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/create.png">
* <p>
* Write the function you pass to <code>create</code> so that it behaves as an Observable: It
* should invoke the Observer's {@link Observer#onNext onNext},
* {@link Observer#onError onError}, and {@link Observer#onCompleted onCompleted} methods
* appropriately.
* <p>
* A well-formed Observable must invoke either the Observer's <code>onCompleted</code> method
* exactly once or its <code>onError</code> method exactly once.
* <p>
* See <a href="http://go.microsoft.com/fwlink/?LinkID=205219">Rx Design Guidelines (PDF)</a>
* for detailed information.
*
* @param <T>
* the type of the items that this Observable emits
* @param func
* a function that accepts an <code>Observer<T></code>, invokes its
* <code>onNext</code>, <code>onError</code>, and <code>onCompleted</code> methods
* as appropriate, and returns a {@link Subscription} to allow the Observer to
* canceling the subscription
* @return an Observable that, when an {@link Observer} subscribes to it, will execute the given
* function
*/
public static <T> Observable<T> create(Func1<Observer<T>, Subscription> func) {
return new Observable<T>(func);
}
/**
* Creates an Observable that will execute the given function when an {@link Observer}
* subscribes to it.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/create.png">
* <p>
* This method accepts {@link Object} to allow different languages to pass in methods using
* {@link FunctionLanguageAdaptor}.
* <p>
* Write the function you pass to <code>create</code> so that it behaves as an Observable: It
* should invoke the Observer's {@link Observer#onNext onNext},
* {@link Observer#onError onError}, and {@link Observer#onCompleted onCompleted} methods
* appropriately.
* <p>
* A well-formed Observable must invoke either the Observer's <code>onCompleted</code> method
* exactly once or its <code>onError</code> method exactly once.
* <p>
* See <a href="http://go.microsoft.com/fwlink/?LinkID=205219">Rx Design Guidelines (PDF)</a>
* for detailed information.
*
* @param <T>
* the type of the items that this Observable emits
* @param func
* a function that accepts an <code>Observer<T></code>, invokes its
* <code>onNext</code>, <code>onError</code>, and <code>onCompleted</code> methods
* as appropriate, and returns a {@link Subscription} that allows the Observer to
* cancel the subscription
* @return an Observable that, when an {@link Observer} subscribes to it, will execute the given
* function
*/
public static <T> Observable<T> create(final Object func) {
@SuppressWarnings("rawtypes")
final FuncN _f = Functions.from(func);
return create(new Func1<Observer<T>, Subscription>() {
@Override
public Subscription call(Observer<T> t1) {
return (Subscription) _f.call(t1);
}
});
}
/**
* Returns an Observable that emits no data to the {@link Observer} and immediately invokes
* its {@link Observer#onCompleted onCompleted} method.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/empty.png">
*
* @param <T>
* the type of the items (ostensibly) emitted by the Observable
* @return an Observable that returns no data to the {@link Observer} and immediately invokes
* the {@link Observer}'s {@link Observer#onCompleted() onCompleted} method
*/
public static <T> Observable<T> empty() {
return toObservable(new ArrayList<T>());
}
/**
* Returns an Observable that invokes an {@link Observer}'s {@link Observer#onError onError}
* method when the Observer subscribes to it
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/error.png">
*
* @param exception
* the particular error to report
* @param <T>
* the type of the items (ostensibly) emitted by the Observable
* @return an Observable that invokes the {@link Observer}'s
* {@link Observer#onError onError} method when the Observer subscribes to it
*/
public static <T> Observable<T> error(Exception exception) {
return new ThrowObservable<T>(exception);
}
/**
* Filters an Observable by discarding any items it emits that do not meet some test.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/filter.png">
*
* @param that
* the Observable to filter
* @param predicate
* a function that evaluates the items emitted by the source Observable, returning
* <code>true</code> if they pass the filter
* @return an Observable that emits only those items emitted by the source Observable that the
* filter evaluates as <code>true</code>
*/
public static <T> Observable<T> filter(Observable<T> that, Func1<T, Boolean> predicate) {
return create(OperationFilter.filter(that, predicate));
}
/**
* Filters an Observable by discarding any items it emits that do not meet some test.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/filter.png">
*
* @param that
* the Observable to filter
* @param function
* a function that evaluates an item emitted by the source Observable, and
* returns <code>true</code> if it passes the filter
* @return an Observable that emits only those items emitted by the source Observable that the
* filter evaluates as <code>true</code>
*/
public static <T> Observable<T> filter(Observable<T> that, final Object function) {
@SuppressWarnings("rawtypes")
final FuncN _f = Functions.from(function);
return filter(that, new Func1<T, Boolean>() {
@Override
public Boolean call(T t1) {
return (Boolean) _f.call(t1);
}
});
}
/**
* Filters an Observable by discarding any items it emits that do not meet some test.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/where.png">
*
* @param that
* the Observable to filter
* @param predicate
* a function that evaluates an item emitted by the source Observable, and
* returns <code>true</code> if it passes the filter
* @return an Observable that emits only those items emitted by the source Observable that the
* filter evaluates as <code>true</code>
*/
public static <T> Observable<T> where(Observable<T> that, Func1<T, Boolean> predicate) {
return create(OperationWhere.where(that, predicate));
}
/**
* Converts an {@link Iterable} sequence into an Observable.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/from.png">
*
* @param iterable
* the source {@link Iterable} sequence
* @param <T>
* the type of items in the {@link Iterable} sequence and the type of items to be
* emitted by the resulting Observable
* @return an Observable that emits each item in the source {@link Iterable} sequence
* @see #toObservable(Iterable)
*/
public static <T> Observable<T> from(Iterable<T> iterable) {
return toObservable(iterable);
}
/**
* Converts an Array into an Observable.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/from.png">
*
* @param items
* the source Array
* @param <T>
* the type of items in the Array, and the type of items to be emitted by the
* resulting Observable
* @return an Observable that emits each item in the source Array
* @see #toObservable(Object...)
*/
public static <T> Observable<T> from(T... items) {
return toObservable(items);
}
/**
* Generates an Observable that emits a sequence of integers within a specified range.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/range.png">
*
* @param start
* the value of the first integer in the sequence
* @param count
* the number of sequential integers to generate
*
* @return an Observable that emits a range of sequential integers
*
* @see <a href="http://msdn.microsoft.com/en-us/library/hh229460(v=vs.103).aspx">Observable.Range Method (Int32, Int32)</a>
*/
public static Observable<Integer> range(int start, int count) {
return from(Range.createWithCount(start, count));
}
/**
* Asynchronously subscribes and unsubscribes Observers on the specified {@link Scheduler}.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/subscribeOn.png">
*
* @param source
* the source Observable
* @param scheduler
* the {@link Scheduler} to perform subscription and unsubscription actions on
* @param <T>
* the type of the items emitted by the Observable
* @return the source Observable modified so that its subscriptions and unsubscriptions happen
* on the specified {@link Scheduler}
*/
public static <T> Observable<T> subscribeOn(Observable<T> source, Scheduler scheduler) {
return create(OperationSubscribeOn.subscribeOn(source, scheduler));
}
/**
* Asynchronously notify Observers on the specified {@link Scheduler}.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/observeOn.png">
*
* @param source
* the source Observable
* @param scheduler
* the {@link Scheduler} to notify Observers on
* @param <T>
* the type of the items emitted by the Observable
* @return the source Observable modified so that its Observers are notified on the specified
* {@link Scheduler}
*/
public static <T> Observable<T> observeOn(Observable<T> source, Scheduler scheduler) {
return create(OperationObserveOn.observeOn(source, scheduler));
}
/**
* Returns an Observable that calls an Observable factory to create its Observable for each
* new Observer that subscribes.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/defer.png">
* <p>
* The defer operator allows you to defer or delay emitting items from an Observable until such
* time as an Observer subscribes to the Observable. This allows an {@link Observer} to easily
* obtain updates or a refreshed version of the sequence.
*
* @param observableFactory
* the Observable factory function to invoke for each {@link Observer} that
* subscribes to the resulting Observable
* @param <T>
* the type of the items emitted by the Observable
* @return an Observable whose {@link Observer}s trigger an invocation of the given Observable
* factory function
*/
public static <T> Observable<T> defer(Func0<Observable<T>> observableFactory) {
return create(OperationDefer.defer(observableFactory));
}
/**
* Returns an Observable that calls an Observable factory to create its Observable for each
* new Observer that subscribes.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/defer.png">
* <p>
* The defer operator allows you to defer or delay emitting items from an Observable
* until such time as an {@link Observer} subscribes to the Observable. This allows an Observer
* to easily obtain an updates or refreshed version of the sequence.
*
* @param observableFactory
* the Observable factory function to invoke for each {@link Observer} that
* subscribes to the resulting Observable
* @param <T>
* the type of the items emitted by the Observable
* @return an Observable whose {@link Observer}s trigger an invocation of the given Observable
* factory function
*/
public static <T> Observable<T> defer(Object observableFactory) {
@SuppressWarnings("rawtypes")
final FuncN _f = Functions.from(observableFactory);
return create(OperationDefer.defer(new Func0<Observable<T>>() {
@Override
@SuppressWarnings("unchecked")
public Observable<T> call() {
return (Observable<T>) _f.call();
}
}));
}
/**
* Returns an Observable that emits a single item and then completes.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/just.png">
* <p>
* To convert any object into an Observable that emits that object, pass that object into the
* <code>just</code> method.
* <p>
* This is similar to the {@link #from(java.lang.Object[])} method, except that
* <code>from()</code> will convert an {@link Iterable} object into an Observable that emits
* each of the items in the Iterable, one at a time, while the <code>just()</code> method
* converts an Iterable into an Observable that emits the entire Iterable as a single item.
*
* @param value
* the item to pass to the {@link Observer}'s {@link Observer#onNext onNext} method
* @param <T>
* the type of that item
* @return an Observable that emits a single item and then completes
*/
public static <T> Observable<T> just(T value) {
List<T> list = new ArrayList<T>();
list.add(value);
return toObservable(list);
}
/**
* Applies a function of your choosing to every item emitted by an Observable, and emits the
* results of these transformations as its own Observable items.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/map.png">
*
* @param sequence
* the source Observable
* @param func
* a function to apply to each item emitted by the source Observable
* @param <T>
* the type of items emitted by the the source Observable
* @param <R>
* the type of items to be emitted by the resulting Observable
* @return an Observable that emits the items from the source Observable as transformed by the
* given function
*/
public static <T, R> Observable<R> map(Observable<T> sequence, Func1<T, R> func) {
return create(OperationMap.map(sequence, func));
}
/**
* Applies a function of your choosing to every item emitted by an Observable, and emits the
* results of these transformations as its own Observable items.
* <p>
* <img width="640" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/map.png">
*
* @param sequence
* the source Observable
* @param func