Optional (Apache Wayang (incubating) 0.7.1 API)

java.lang.Object
- org.apache.wayang.core.util.Optional<T>

```
public abstract class Optional<T>
extends java.lang.Object
```
Utility similar to Optional. However, it supports null as a valid value.

Constructor Summary

Constructors
Constructor Description

Optional()

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract T`	`getValue()`
`abstract boolean`	`isAvailable()`
`static <T> Optional<T>`	`na()`	Create a n/a instance.
`static <T> Optional<T>`	`of(T value)`	Create a new instance with the given `value`.
`abstract java.util.stream.Stream<T>`	`stream()`

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

- Constructor Detail
  - Optional
```
public Optional()
```
- Method Detail
  - isAvailable
```
public abstract boolean isAvailable()
```
    Returns:
    
    whether this instance contains a value.
  - getValue
```
public abstract T getValue()
```
    Returns:
    
    the value contained by this instance
    
    Throws:
    
    java.lang.IllegalStateException - if isAvailable() is false
  - stream
```
public abstract java.util.stream.Stream<T> stream()
```
    Returns:
    
    a Stream containing the optional value
  - na
```
public static <T> Optional<T> na()
```
    Create a n/a instance.
    
    Returns:
    
    an Optional without a value
  - of
```
public static <T> Optional<T> of(T value)
```
    Create a new instance with the given value.
    
    Parameters:
    
    value - the value of the new Optional
    
    Returns:
    
    the new instance