Absent

java.lang.Object
- com.google.common.base.Optional<T>
- - com.google.common.base.Absent<T>

All Implemented Interfaces:

java.io.Serializable
```
@GwtCompatible
final class Absent<T>
extends Optional<T>
```
Implementation of an Optional not containing a reference.

Field Summary

Fields
Modifier and Type Field and Description

(package private) static Absent<java.lang.Object> INSTANCE

private static long serialVersionUID

Fields
Modifier and Type	Field and Description
`(package private) static Absent<java.lang.Object>`	`INSTANCE`
`private static long`	`serialVersionUID`

Constructor Summary

Constructors
Modifier Constructor and Description

private Absent()

Constructors
Modifier	Constructor and Description
`private`	`Absent()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`java.util.Set<T>`	`asSet()` Returns an immutable singleton `Set` whose only element is the contained instance if it is present; an empty immutable `Set` otherwise.
`boolean`	`equals(java.lang.Object object)` Returns `true` if `object` is an `Optional` instance, and either the contained references are equal to each other or both are absent.
`T`	`get()` Returns the contained instance, which must be present.
`int`	`hashCode()` Returns a hash code for this instance.
`boolean`	`isPresent()` Returns `true` if this holder contains a (non-null) instance.
`Optional<T>`	`or(Optional<? extends T> secondChoice)` Returns this `Optional` if it has a value present; `secondChoice` otherwise.
`T`	`or(Supplier<? extends T> supplier)` Returns the contained instance if it is present; `supplier.get()` otherwise.
`T`	`or(T defaultValue)` Returns the contained instance if it is present; `defaultValue` otherwise.
`T`	`orNull()` Returns the contained instance if it is present; `null` otherwise.
`private java.lang.Object`	`readResolve()`
`java.lang.String`	`toString()` Returns a string representation for this instance.
`<V> Optional<V>`	`transform(Function<? super T,V> function)` If the instance is present, it is transformed with the given `Function`; otherwise, `Optional.absent()` is returned.
`(package private) static <T> Optional<T>`	`withType()`

Methods inherited from class com.google.common.base.Optional
absent, fromNullable, of, presentInstances

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

- Field Detail
  - INSTANCE
```
static final Absent<java.lang.Object> INSTANCE
```
  - serialVersionUID
```
private static final long serialVersionUID
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - Absent
```
private Absent()
```
- Method Detail
  - withType
```
static <T> Optional<T> withType()
```
  - isPresent
```
public boolean isPresent()
```
    Description copied from class: Optional
    
    Returns true if this holder contains a (non-null) instance.
    
    Specified by:
    
    isPresent in class Optional<T>
  - get
```
public T get()
```
    Description copied from class: Optional
    
    Returns the contained instance, which must be present. If the instance might be absent, use Optional.or(Object) or Optional.orNull() instead.
    
    Specified by:
    
    get in class Optional<T>
  - or
```
public T or(T defaultValue)
```
    Description copied from class: Optional
    Returns the contained instance if it is present; defaultValue otherwise. If no default value should be required because the instance is known to be present, use Optional.get() instead. For a default value of null, use Optional.orNull().
    Note about generics: The signature public T or(T defaultValue) is overly restrictive. However, the ideal signature, public <S super T> S or(S), is not legal Java. As a result, some sensible operations involving subtypes are compile errors:
```
   

   Optional<Integer> optionalInt = getSomeOptionalInt();
   Number value = optionalInt.or(0.5); // error

   FluentIterable<? extends Number> numbers = getSomeNumbers();
   Optional<? extends Number> first = numbers.first();
   Number value = first.or(0.5); // error
```
    As a workaround, it is always safe to cast an Optional<? extends T> to Optional<T>. Casting either of the above example Optional instances to Optional<Number> (where Number is the desired output type) solves the problem:
```
   

   Optional<Number> optionalInt = (Optional) getSomeOptionalInt();
   Number value = optionalInt.or(0.5); // fine

   FluentIterable<? extends Number> numbers = getSomeNumbers();
   Optional<Number> first = (Optional) numbers.first();
   Number value = first.or(0.5); // fine
```
    Specified by:
    
    or in class Optional<T>
  - or
```
public Optional<T> or(Optional<? extends T> secondChoice)
```
    Description copied from class: Optional
    
    Returns this Optional if it has a value present; secondChoice otherwise.
    
    Specified by:
    
    or in class Optional<T>
  - or
```
public T or(Supplier<? extends T> supplier)
```
    Description copied from class: Optional
    
    Returns the contained instance if it is present; supplier.get() otherwise. If the supplier returns null, a NullPointerException is thrown.
    
    Specified by:
    
    or in class Optional<T>
  - orNull
```
@Nullable
public T orNull()
```
    Description copied from class: Optional
    
    Returns the contained instance if it is present; null otherwise. If the instance is known to be present, use Optional.get() instead.
    
    Specified by:
    
    orNull in class Optional<T>
  - asSet
```
public java.util.Set<T> asSet()
```
    Description copied from class: Optional
    
    Returns an immutable singleton Set whose only element is the contained instance if it is present; an empty immutable Set otherwise.
    
    Specified by:
    
    asSet in class Optional<T>
  - transform
```
public <V> Optional<V> transform(Function<? super T,V> function)
```
    Description copied from class: Optional
    
    If the instance is present, it is transformed with the given Function; otherwise, Optional.absent() is returned. If the function returns null, a NullPointerException is thrown.
    
    Specified by:
    
    transform in class Optional<T>
  - equals
```
public boolean equals(@Nullable
                      java.lang.Object object)
```
    Description copied from class: Optional
    
    Returns true if object is an Optional instance, and either the contained references are equal to each other or both are absent. Note that Optional instances of differing parameterized types can be equal.
    
    Specified by:
    
    equals in class Optional<T>
  - hashCode
```
public int hashCode()
```
    Description copied from class: Optional
    
    Returns a hash code for this instance.
    
    Specified by:
    
    hashCode in class Optional<T>
  - toString
```
public java.lang.String toString()
```
    Description copied from class: Optional
    
    Returns a string representation for this instance. The form of this string representation is unspecified.
    
    Specified by:
    
    toString in class Optional<T>
  - readResolve
```
private java.lang.Object readResolve()
```

Class Absent<T>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.google.common.base.Optional

Methods inherited from class java.lang.Object

Field Detail

INSTANCE

serialVersionUID

Constructor Detail

Absent

Method Detail

withType

isPresent

get

or

or

or

orNull

asSet

transform

equals

hashCode

toString

readResolve