net.markenwerk.commons.datastructures

Class Optional<Payload>

java.lang.Object

net.markenwerk.commons.datastructures.Optional<Payload>

Type Parameters:

Payload - The payload type.

public final class Optional<Payload>
extends Object

An Optional is a simple immutable container class that may holds a single value.

Since:

1.0.0

Author:

Torsten Krause (tk at markenwerk dot net)

Constructor Summary

Constructors

Constructor and Description
Optional() Creates a new Optional without a value.
Optional(Payload value) Creates a new Optional.
Optional(Payload value, boolean ignoreNull) Creates a new Optional.

Method Summary

Modifier and Type	Method and Description
<Result> Optional<Result>	convert(Converter<? super Payload,? extends Result> converter) Converts the payload value of this Optional, if present, and returns another Optional.
boolean	equals(Object object)
Payload	getValue() Returns the value this Optional has been created with, if any.
Payload	getValue(Payload fallback) Returns the value this Optional has been created with, if any, or the given fallback payload value.
Payload	getValue(Provider<? extends Payload> provider) Returns the value this Optional has been created with, if any, or a payload value provided by the given Provider.
int	hashCode()
boolean	hasValue() Returns whether this Optional has a value.
<Result> Result	select(OptionalSelection<? super Payload,? extends Result> selection) Calls the appropriate method on the given OptionalSelection.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Optional

public Optional()

Creates a new Optional without a value.

Optional

public Optional(Payload value)

Creates a new Optional.

Parameters:

value - The value to be used.

Optional

public Optional(Payload value,
                boolean ignoreNull)

Creates a new Optional.

Parameters:

value - The value to be used.

ignoreNull - Whether to ignore null-values.

Method Detail

hasValue

public boolean hasValue()

Returns whether this Optional has a value.

Returns:

Whether this Optional has a value.

getValue

public Payload getValue()
                 throws NoSuchElementException

Returns the value this Optional has been created with, if any.

Returns:

The value.

Throws:

NoSuchElementException - If this Optional has no value.

getValue

public Payload getValue(Payload fallback)

Returns the value this Optional has been created with, if any, or the given fallback payload value.

Parameters:

fallback - The fallback payload value to be used.

Returns:

The value.

getValue

public Payload getValue(Provider<? extends Payload> provider)
                 throws IllegalArgumentException,
                        ProvisioningException

Returns the value this Optional has been created with, if any, or a payload value provided by the given Provider.

Parameters:

provider - The Provider to be used.

Returns:

The value.

Throws:

IllegalArgumentException - If the given Provider is null.

ProvisioningException - If the given Provider failed to provide a fallback payload value.

convert

public <Result> Optional<Result> convert(Converter<? super Payload,? extends Result> converter)
                                  throws IllegalArgumentException

Converts the payload value of this Optional, if present, and returns another Optional.

Type Parameters:

Result - The result type.

Parameters:

converter - The Converter to be used.

Returns:

The result value returned by the given OptionalSelection.

Throws:

IllegalArgumentException - If the given Converter is null.

select

public <Result> Result select(OptionalSelection<? super Payload,? extends Result> selection)
                       throws IllegalArgumentException

Calls the appropriate method on the given OptionalSelection.

Type Parameters:

Result - The result type.

Parameters:

selection - The OptionalSelection to be used.

Returns:

The result value returned by the given OptionalSelection.

Throws:

IllegalArgumentException - If the given OptionalSelection is null.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object object)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object