OrElse

java.lang.Object
- akka.stream.stage.GraphStageWithMaterializedValue<S,NotUsed>
- - akka.stream.stage.GraphStage<UniformFanInShape<T,T>>
  - - akka.stream.scaladsl.OrElse<T>

All Implemented Interfaces:

Graph<UniformFanInShape<T,T>,NotUsed>
```
public final class OrElse<T>
extends GraphStage<UniformFanInShape<T,T>>
```
Takes two streams and passes the first through, the secondary stream is only passed through if the primary stream completes without passing any elements through. When the first element is passed through from the primary the secondary is cancelled. Both incoming streams are materialized when the operator is materialized.
On errors the operator is failed regardless of source of the error.
'''Emits when''' element is available from primary stream or the primary stream closed without emitting any elements and an element is available from the secondary stream
'''Backpressures when''' downstream backpressures
'''Completes when''' the primary stream completes after emitting at least one element, when the primary stream completes without emitting and the secondary stream already has completed or when the secondary stream completes
'''Cancels when''' downstream cancels

Constructor Summary

Constructors
Constructor Description

OrElse()

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static <T> OrElse<T>`	`apply()`
`GraphStageLogic`	`createLogic(Attributes inheritedAttributes)`
`protected Attributes`	`initialAttributes()`
`Outlet<T>`	`out()`
`Inlet<T>`	`primary()`
`Inlet<T>`	`secondary()`
`UniformFanInShape<T,T>`	`shape()`	The shape of a graph is all that is externally visible: its inlets and outlets.
`java.lang.String`	`toString()`

Methods inherited from class akka.stream.stage.GraphStage
createLogicAndMaterializedValue

Methods inherited from class akka.stream.stage.GraphStageWithMaterializedValue
createLogicAndMaterializedValue, traversalBuilder, withAttributes

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface akka.stream.Graph
addAttributes, async, async, async, named

- Constructor Detail
  - OrElse
```
public OrElse()
```
- Method Detail
  - apply
```
public static <T> OrElse<T> apply()
```
    Returns:
    
    (undocumented)
    
    See Also:
    
    OrElse
  - primary
```
public Inlet<T> primary()
```
  - secondary
```
public Inlet<T> secondary()
```
  - out
```
public Outlet<T> out()
```
  - shape
```
public UniformFanInShape<T,T> shape()
```
    Description copied from interface: Graph
    
    The shape of a graph is all that is externally visible: its inlets and outlets.
    
    Returns:
    
    (undocumented)
  - initialAttributes
```
protected Attributes initialAttributes()
```
    Overrides:
    
    initialAttributes in class GraphStageWithMaterializedValue<UniformFanInShape<T,T>,NotUsed>
  - createLogic
```
public GraphStageLogic createLogic(Attributes inheritedAttributes)
```
    Specified by:
    
    createLogic in class GraphStage<UniformFanInShape<T,T>>
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object