javascalautils

Class OptionCompanion

java.lang.Object

javascalautils.OptionCompanion

public final class OptionCompanion
extends Object

Acts as a Scala type companion object for Option/Some/None.
The primary purpose is to get the Scala feel of instantiating classes.
In Scala you can define a companion object for a class, acting as a static reference/singleton for that class allowing you do define factory methods.
One use case is to define methods with the same name as the class and let these methods invoke the constructor thus creating a nice way to create instances without using the word "new".
This can be achieved in java by statically importing a method and then using it.
The limitation is that classes may not have method with the same name as the class itself hence new companion classes have to be created.
To be able to use it in a neat concise way one needs to statically import the method.

 import static javascalautils.OptionCompanion.Option;
 import static javascalautils.OptionCompanion.Some;
 import static javascalautils.OptionCompanion.None;
 
 Option<String> option = Option("Life is full of options");
 Option<String> some = Some("Some is never None");
 Option<String> none = None();
 

Since:

1.3

Author:

Peter Nerg

Method Summary

Modifier and Type	Method and Description
static <T> None<T>	None() Returns an instance of None.
static <T> Option<T>	Option(T value) Creates an instance of Option.
static <T> Some<T>	Some(T value) Creates an instance of Some.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

Option

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

Creates an instance of Option.
If a null value is provided then None is returned, else Some containing the provided value.
Best used in conjunction with statically importing this method.

 import static javascalautils.OptionCompanion.Option;
 
 Option<String> option = Option("Life is full of options");
 

Type Parameters:

T - The type for the value this Option represents

Parameters:

value - The value this Option shall represent

Returns:

The Option representing the provided value

See Also:

Option.apply(Object)

Some

public static <T> Some<T> Some(T value)

Creates an instance of Some.
Best used in conjunction with statically importing this method.

 import static javascalautils.OptionCompanion.Some;
 
 Option<String> some = Some("Some is never None");
 

Type Parameters:

T - The type for the value this Some represents

Parameters:

value - The value represented by this Some

Returns:

The Some representing the value

See Also:

Some.Some(Object)

None

public static <T> None<T> None()

Returns an instance of None.
In practice returns the singleton instance for None, never creates new instances.
Best used in conjunction with statically importing this method.

 import static javascalautils.OptionCompanion.None;
 
 Option<String> none = None();
 

Type Parameters:

T - The type for the value this None represents

Returns:

The singleton instance for None

See Also:

Option.None(), Option.empty(), Option.DEFAULT_NONE