org.gonn.gava

Class Box<T>

java.lang.Object

org.gonn.gava.Box<T>

Type Parameters:

T - Type of the content to be boxed

public class Box<T>
extends Object

Box an object just like the java.util.Optional

Version:

0.0.2

Author:

Gon Yi

Constructor Summary

Constructors

Constructor and Description
Box(T t) Box object with T in it.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
T	get() Get the box content.
T	get(T fallback) Get the box content.
int	hashCode()
boolean	isEmpty() Check if the box content is NULL.
boolean	isFull() Check if the box content is NOT NULL.
<R> Box<R>	map(FnTR<T,R> mapFn) Converts box content to a new content in a box.
<R> Box<R>	map(FnTR<T,R> mapFn, R fallback) Converts box content to a new content in a box.
static <T> Box<T>	of(T obj) Static constructor:
Box<T>	or(T fallback) If the box is empty, returns the box with the fallback value
Box<T>	orElse(FnR<T> fallbackFn) If the box is empty, returns the box with the fallback value
<E extends Throwable> Box<T>	orThrow(E exception) If the box is empty (content is null), throw an exception.
Box<T>	then(FnT<T> modFn) View or modifying the box content.
Box<T>	thenSet(FnTR<T,T> modFn) Replace the box content.

Methods inherited from class java.lang.Object

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

Constructor Detail

Box

public Box(T t)

Box object with T in it.

Parameters:

t - Boxed T.

Method Detail

of

public static <T> Box<T> of(T obj)

Static constructor:

Type Parameters:

T - Type of the target object.

Parameters:

obj - A target object to be boxed.

Returns:

Boxed target object.

isEmpty

public boolean isEmpty()

Check if the box content is NULL.

Returns:

true if the content is NULL.

isFull

public boolean isFull()

Check if the box content is NOT NULL.

Returns:

true if the content is full.

get

public T get()

Get the box content. When the box is empty, this will return null.

Returns:

Content of the box.

get

public T get(T fallback)

Get the box content. If it is null, return the fallback instead.

Parameters:

fallback - A value to be returned when the box is empty.

Returns:

Content of the box.

then

public Box<T> then(FnT<T> modFn)

View or modifying the box content. This is for a mutable content. Use thenSet() for immutable content.

Parameters:

modFn - A function that can view or modify the content.

Returns:

self

thenSet

public Box<T> thenSet(FnTR<T,T> modFn)

Replace the box content. This is to replace the immutable content in a box. Content of the box will be replaced with the output of modFn. NOTE: This is between same content type. Use "map" method in order to change to a different type.

Parameters:

modFn - A function that takes and returns type T data.

Returns:

self

or

public Box<T> or(T fallback)

If the box is empty, returns the box with the fallback value

Parameters:

fallback - A fallback T when the box is empty.

Returns:

Self

orElse

public Box<T> orElse(FnR<T> fallbackFn)

If the box is empty, returns the box with the fallback value

Parameters:

fallbackFn - A function that returns fallback value T.

Returns:

Self

orThrow

public <E extends Throwable> Box<T> orThrow(E exception)
                                     throws E extends Throwable

If the box is empty (content is null), throw an exception.

Type Parameters:

E - Any throwable object.

Parameters:

exception - Exception to be thrown when the box is empty.

Returns:

Self

Throws:

E - Any Throwable exception

E extends Throwable

map

public <R> Box<R> map(FnTR<T,R> mapFn)

Converts box content to a new content in a box.

Type Parameters:

R - New return type

Parameters:

mapFn - Lambda function which takes current content, and returns a Box with new type of content.

Returns:

new boxed R.

map

public <R> Box<R> map(FnTR<T,R> mapFn,
                      R fallback)

Converts box content to a new content in a box. If the mapFn fails, this will return a box with the fallback value.

Type Parameters:

R - New return type

Parameters:

mapFn - Lambda function which takes current content, and returns a Box with new type of content.

fallback - Fallback value that will be boxed when mapFn throws an exception. Note that if mapFn returns null, this fallback won't be called.

Returns:

new boxed R

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object