Class BehaviorSubject<T>

Represents a value that changes over time. Observers can subscribe to the subject to receive the last (or initial) value and all subsequent notifications.

Inheritance
Object
BehaviorSubject<T>
Implements
ISubject<T, T>
Inherited Members
Namespace: System.Reactive.Subjects
Assembly: System.Reactive.Linq.dll
Syntax
public sealed class BehaviorSubject<T> : ISubject<T>, ISubject<T, T>, IObserver<T>, IObservable<T>, IDisposable
Type Parameters
Name Description
T

The type of the elements processed by the subject.

Constructors

| Improve this Doc View Source

BehaviorSubject(T)

Initializes a new instance of the BehaviorSubject<T> class which creates a subject that caches its last value and starts with the specified value.

Declaration
public BehaviorSubject(T value)
Parameters
Type Name Description
T value

Initial value sent to observers when no other value has been received by the subject yet.

Properties

| Improve this Doc View Source

HasObservers

Indicates whether the subject has observers subscribed to it.

Declaration
public bool HasObservers { get; }
Property Value
Type Description
Boolean
| Improve this Doc View Source

Value

Gets the current value or throws an exception.

Declaration
public T Value { get; }
Property Value
Type Description
T

The initial value passed to the constructor until OnNext(T) is called; after which, the last value passed to OnNext(T).
Remarks

Value is frozen after OnCompleted() is called.

After OnError(Exception) is called, Value always throws the specified exception.

An exception is always thrown after Dispose() is called.

Reading Value is a thread-safe operation, though there's a potential race condition when OnNext(T) or OnError(Exception) are being invoked concurrently. In some cases, it may be necessary for a caller to use external synchronization to avoid race conditions.
Exceptions
Type Condition
ObjectDisposedException

Dispose was called.

Methods

| Improve this Doc View Source

Dispose()

Unsubscribe all observers and release resources.

Declaration
public void Dispose()
| Improve this Doc View Source

OnCompleted()

Notifies all subscribed observers about the end of the sequence.

Declaration
public void OnCompleted()
| Improve this Doc View Source

OnError(Exception)

Notifies all subscribed observers about the exception.

Declaration
public void OnError(Exception error)
Parameters
Type Name Description
Exception error

The exception to send to all observers.
Exceptions
Type Condition
ArgumentNullException

error is null.
| Improve this Doc View Source

OnNext(T)

Notifies all subscribed observers about the arrival of the specified element in the sequence.

Declaration
public void OnNext(T value)
Parameters
Type Name Description
T value

The value to send to all observers.
| Improve this Doc View Source

Subscribe(IObserver<T>)

Subscribes an observer to the subject.

Declaration
public IDisposable Subscribe(IObserver<T> observer)
Parameters
Type Name Description
IObserver<T> observer

Observer to subscribe to the subject.
Returns
Type Description
IDisposable

Disposable object that can be used to unsubscribe the observer from the subject.
Exceptions
Type Condition
ArgumentNullException

observer is null.

Implements

Extension Methods