net.ninjacat.smooth.utils

Class Option<T>

java.lang.Object

net.ninjacat.smooth.utils.Option<T>

Type Parameters:

T - - type of wrapped value

public class Option<T>
extends Object

An immutable object that contains either a non-null reference to another object or contains nothing, i.e. absent. It is never null.

Method Summary

Modifier and Type	Method and Description
static <T> Option<T>	absent() Creates a new option that does not hold any value.
boolean	equals(Object o)
T	get() Retrieves wrapped value.
int	hashCode()
void	ifPresent(Procedure<T> proc) Executes Procedure if this option has value.
boolean	isPresent()
<K> Option<K>	map(Func<K,T> transform) If this option is not empty, its value is transformed with the given Function; otherwise, absent() is returned.
static <T> Option<T>	of(T value) Creates a new option from supplied value.
T	or(T alternative) Returns wrapped value, if this Option is not absent or supplied alternative otherwise.
T	orGet(Provider<T> provider) Returns wrapped value if this Option is not absent, otherwise calls supplied Provider to calculate a new value.
T	orNull()
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

absent

public static <T> Option<T> absent()

Creates a new option that does not hold any value.

Type Parameters:

T - Type of optional value.

Returns:

A new empty optional value.

of

public static <T> Option<T> of(T value)

Creates a new option from supplied value. Value can be null.

Type Parameters:

T - Type of optional value.

Parameters:

value - Value to wrap into Option

Returns:

A new optional value.

isPresent

public boolean isPresent()

Returns:

true if this Option is not absent, or false otherwise.

ifPresent

public void ifPresent(Procedure<T> proc)

Executes Procedure if this option has value.

Parameters:

proc - Procedure that accepts parameter of the type of the Option

or

public T or(T alternative)

Returns wrapped value, if this Option is not absent or supplied alternative otherwise.

Parameters:

alternative - Alternative value to return if this Option is absent.

Returns:

Wrapped value.

orGet

public T orGet(Provider<T> provider)

Returns wrapped value if this Option is not absent, otherwise calls supplied Provider to calculate a new value.

Parameters:

provider - Provider to create an alternative value/

Returns:

Wrapped or generated value.

orNull

public T orNull()

Returns:

Wrapped value or null if this Option is absent.

get

public T get()

Retrieves wrapped value. If this Option is empty, then NullPointerException will be thrown.

Returns:

Wrapped value.

Throws:

NullPointerException - if Option is empty.

map

public <K> Option<K> map(Func<K,T> transform)

If this option is not empty, its value is transformed with the given Function; otherwise, absent() is returned. Function is permitted to return null, in this case absent() will be returned.

If function throws exception, absent() will be returned.

Type Parameters:

K - Type of the new value

Parameters:

transform - Function Func to transform value from one type to another.

Returns:

Optional value (or absent Option).

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object