com.github.bicoco.collections

Class ListHelper<T>

java.lang.Object

com.github.bicoco.collections.ListHelper<T>

public class ListHelper<T>
extends Object

Helper methods to List Java Interface

Since:

1.0

Constructor Summary

Constructors

Constructor and Description
ListHelper(List<T> list) Default constructor.

Method Summary

Modifier and Type	Method and Description
boolean	all(ConditionFunction<T> function) Returns true if all of the values in the list pass the predicate truth test
boolean	any(ConditionFunction<T> function) Returns true if any of the values in the list pass the predicate truth test
T	at(int index) Return the element at index.
void	compact$() Remove null values of list.
int	count() Return size of list or 0 to empty list.
int	count(ConditionFunction<T> function) Return size of list where function returns true, or 0 to empty list.
List<T>	drop(int n) Get the elements of list excluding the first n elements.
void	each(EachFunction<T> function) Execute a custom action for each element of list.
T	fetch(int index) Identical to List.get(int).
T	fetch(int index, T def) Null-safe, defining the default value.
T	first() Get the first element of list.
boolean	isEmpty() Check if list is empty
boolean	isNotEmpty() Check if list is not empty
T	last() Get the last element of list.
List<T>	map(MapFunction<T> function) Return a new list of same type element, applying new value for each element.
void	map$(MapFunction<T> function) Modifing list applying new value for each element.
void	push(T... ts) Adding multiple elements to the end of list.
ListHelper<T>	push(T t) Adding element to the end of list.
<R> R	reduce(R initialValue, ReduceFunction<T,R> function) Transform a list on a single value
List<T>	reject(ConditionFunction<T> function) Select all elements that condition returns false.
void	reject$(ConditionFunction<T> function) Select all elements that condition returns false.
List<T>	select(ConditionFunction<T> function) Select all elements that condition returns true.
void	select$(ConditionFunction<T> function) Select all elements that condition returns true.
int	size() Identical to List#size()
List<T>	take(int n) Get the first n elements of list.
<R> List<R>	transform(TransformFunction<T,R> function) Return a new list of another type element, applying a function for each element.

Methods inherited from class java.lang.Object

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

Constructor Detail

ListHelper

public ListHelper(List<T> list)

Default constructor.

Parameters:

list - the list to execute operations

Method Detail

each

public void each(EachFunction<T> function)

Execute a custom action for each element of list.

Parameters:

function - function to execute in each element

map

public List<T> map(MapFunction<T> function)

Return a new list of same type element, applying new value for each element.

Parameters:

function - function to apply in each value that returns the new value

Returns:

changed list of same type element

transform

public <R> List<R> transform(TransformFunction<T,R> function)

Return a new list of another type element, applying a function for each element.

Parameters:

function - function to apply in each element of list

Returns:

list of elements transformed

select

public List<T> select(ConditionFunction<T> function)

Select all elements that condition returns true.

Parameters:

function - Apply in each element and select if returns true.

Returns:

list of elements that the condition is true.

reject

public List<T> reject(ConditionFunction<T> function)

Select all elements that condition returns false.

Parameters:

function - Apply in each element and select if returns true.

Returns:

list of elements that the condition is false.

map$

public void map$(MapFunction<T> function)

Modifing list applying new value for each element.

Parameters:

function - function to apply in each value that returns the new value

select$

public void select$(ConditionFunction<T> function)

Select all elements that condition returns true.

Parameters:

function - Apply in each element and select if returns true.

reject$

public void reject$(ConditionFunction<T> function)

Select all elements that condition returns false.

Parameters:

function - Apply in each element and select if returns false.

compact$

public void compact$()

Remove null values of list.

push

public void push(T... ts)

Adding multiple elements to the end of list.

Parameters:

ts - elements to push

push

public ListHelper<T> push(T t)

Adding element to the end of list.

Parameters:

t - element to push

Returns:

ListHelper to chaining methods

at

public T at(int index)

Return the element at index. Returns null if index is out of range. Negative index counts from the end of list.

Parameters:

index - index of element

Returns:

Element at the index

fetch

public T fetch(int index)

Identical to List.get(int).

Parameters:

index - index of element

Returns:

Object T at param index

Throws:

IndexOutOfBoundsException - if the index is out of range

fetch

public T fetch(int index,
               T def)

Null-safe, defining the default value.

Parameters:

index - index of element

def - Default value

Returns:

element of list or default value

first

public T first()

Get the first element of list.

Returns:

the first element

last

public T last()

Get the last element of list.

Returns:

the last element

take

public List<T> take(int n)

Get the first n elements of list.

Parameters:

n - number of elements

Returns:

List of the first n elements

drop

public List<T> drop(int n)

Get the elements of list excluding the first n elements.

Parameters:

n - number of elements to exclude

Returns:

list of the elements

isEmpty

public boolean isEmpty()

Check if list is empty

Returns:

true if list is null or size is 0.

isNotEmpty

public boolean isNotEmpty()

Check if list is not empty

Returns:

true if list is not null and size is greater than 0.

size

public int size()

Identical to List#size()

Returns:

the size of list

count

public int count()

Return size of list or 0 to empty list.

Returns:

the size of list

count

public int count(ConditionFunction<T> function)

Return size of list where function returns true, or 0 to empty list.

Parameters:

function - the condition to consider element in count

Returns:

the size of list

all

public boolean all(ConditionFunction<T> function)

Returns true if all of the values in the list pass the predicate truth test

Parameters:

function - apply in each element and return false if one of them fail

Returns:

true if all elements pass on test

any

public boolean any(ConditionFunction<T> function)

Returns true if any of the values in the list pass the predicate truth test

Parameters:

function - apply in each element and return true if one of them pass

Returns:

true if any elements pass on test

reduce

public <R> R reduce(R initialValue,
                    ReduceFunction<T,R> function)

Transform a list on a single value

Parameters:

initialValue - initial value of the to be returned

function - the reduce function

Returns:

the value

Since:

1.2