org.apache.storm.daemon.utils

Class ListFunctionalSupport

java.lang.Object

org.apache.storm.daemon.utils.ListFunctionalSupport

public class ListFunctionalSupport
extends Object

Implements missing sequence functions in Java compared to Clojure. To make thing simpler, it only supports List type.

Constructor Summary

Constructors

Constructor and Description
ListFunctionalSupport()

Method Summary

Modifier and Type	Method and Description
static <T> List<T>	drop(List<T> list, int count) Drop the first N elements and create a new list.
static <T> T	first(List<T> list) Get the first element in list.
static <T> T	last(List<T> list) get the last element in list.
static <T> List<T>	rest(List<T> list) Drop the only first element and create a new list.
static <T> List<T>	takeLast(List<T> list, int count) Get the last N elements as a new list.

Methods inherited from class java.lang.Object

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

Constructor Detail

ListFunctionalSupport

public ListFunctionalSupport()

Method Detail

first

public static <T> T first(List<T> list)

Get the first element in list.

Parameters:

list - list to get

Returns:

the first element. null if list is null or empty.

last

public static <T> T last(List<T> list)

get the last element in list.

Parameters:

list - list to get

Returns:

the last element. null if list is null or empty.

takeLast

public static <T> List<T> takeLast(List<T> list,
                                   int count)

Get the last N elements as a new list.

Parameters:

list - list to get

count - element count to get

Returns:

the first element. null if list is null. elements in a new list may be less than count if there're not enough elements in the list.

drop

public static <T> List<T> drop(List<T> list,
                               int count)

Drop the first N elements and create a new list.

Parameters:

list - the list

count - element count to drop

Returns:

newly created sublist that drops the first N elements from origin list. null if list is null.

rest

public static <T> List<T> rest(List<T> list)

Drop the only first element and create a new list. equivalent to drop(list, 1).

Parameters:

list - the list

Returns:

newly created sublist that drops the first element from origin list. null if list is null.

See Also:

ListFunctionalSupport#drop(List, int)}