/**
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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 io.reactivex;
import io.reactivex.annotations.*;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.util.NotificationLite;
/**
* Represents the reactive signal types: onNext, onError and onComplete and
* holds their parameter values (a value, a Throwable, nothing).
* @param <T> the value type
*/
public final class Notification<T> {
final Object value;
/** Not meant to be implemented externally. */
private Notification(Object value) {
this.value = value;
}
/**
* Returns true if this notification is an onComplete signal.
* @return true if this notification is an onComplete signal
*/
public boolean isOnComplete() {
return value == null;
}
/**
* Returns true if this notification is an onError signal and
* {@link #getError()} returns the contained Throwable.
* @return true if this notification is an onError signal
* @see #getError()
*/
public boolean isOnError() {
return NotificationLite.isError(value);
}
/**
* Returns true if this notification is an onNext signal and
* {@link #getValue()} returns the contained value.
* @return true if this notification is an onNext signal
* @see #getValue()
*/
public boolean isOnNext() {
Object o = value;
return o != null && !NotificationLite.isError(o);
}
/**
* Returns the contained value if this notification is an onNext
* signal, null otherwise.
* @return the value contained or null
* @see #isOnNext()
*/
@SuppressWarnings("unchecked")
@Nullable
public T getValue() {
Object o = value;
if (o != null && !NotificationLite.isError(o)) {
return (T)value;
}
return null;
}
/**
* Returns the container Throwable error if this notification is an onError
* signal, null otherwise.
* @return the Throwable error contained or null
* @see #isOnError()
*/
@Nullable
public Throwable getError() {
Object o = value;
if (NotificationLite.isError(o)) {
return NotificationLite.getError(o);
}
return null;
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Notification) {
Notification<?> n = (Notification<?>) obj;
return ObjectHelper.equals(value, n.value);
}
return false;
}
@Override
public int hashCode() {
Object o = value;
return o != null ? o.hashCode() : 0;
}
@Override
public String toString() {
Object o = value;
if (o == null) {
return "OnCompleteNotification";
}
if (NotificationLite.isError(o)) {
return "OnErrorNotification[" + NotificationLite.getError(o) + "]";
}
return "OnNextNotification[" + value + "]";
}
/**
* Constructs an onNext notification containing the given value.
* @param <T> the value type
* @param value the value to carry around in the notification, not null
* @return the new Notification instance
* @throws NullPointerException if value is null
*/
@NonNull
public static <T> Notification<T> createOnNext(@NonNull T value) {
ObjectHelper.requireNonNull(value, "value is null");
return new Notification<T>(value);
}
/**
* Constructs an onError notification containing the error.
* @param <T> the value type
* @param error the error Throwable to carry around in the notification, not null
* @return the new Notification instance
* @throws NullPointerException if error is null
*/
@NonNull
public static <T> Notification<T> createOnError(@NonNull Throwable error) {
ObjectHelper.requireNonNull(error, "error is null");
return new Notification<T>(NotificationLite.error(error));
}
/**
* Returns the empty and stateless shared instance of a notification representing
* an onComplete signal.
* @param <T> the target value type
* @return the shared Notification instance representing an onComplete signal
*/
@SuppressWarnings("unchecked")
@NonNull
public static <T> Notification<T> createOnComplete() {
return (Notification<T>)COMPLETE;
}
/** The singleton instance for createOnComplete. */
static final Notification<Object> COMPLETE = new Notification<Object>(null);
}