org.apache.reef.util

Class CollectionUtils

java.lang.Object

org.apache.reef.util.CollectionUtils

public final class CollectionUtils
extends Object

Utility functions for arrays and collection classes.

Method Summary

Methods

Modifier and Type	Method and Description
static <T> boolean	isEmpty(Collection<T> parameter) Checks if the collection is null or empty.
static <T> boolean	isNotEmpty(Collection<T> parameter) Checks if the collection is not null and not empty.
static <T> T[]	nullToEmpty(T[] array) Return an empty array if input is null; works as identity function otherwise.

Methods inherited from class java.lang.Object

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

Method Detail

isEmpty

public static <T> boolean isEmpty(Collection<T> parameter)

Checks if the collection is null or empty.

Type Parameters:

T - a type of element of collection

Parameters:

parameter - the collection

Returns:

true if the collection is null or empty

isNotEmpty

public static <T> boolean isNotEmpty(Collection<T> parameter)

Checks if the collection is not null and not empty.

Type Parameters:

T - a type of element of collection

Parameters:

parameter - the collection

Returns:

true if the collection is not null nor empty

nullToEmpty

public static <T> T[] nullToEmpty(T[] array)

Return an empty array if input is null; works as identity function otherwise. This function is useful in `for` statements if the iterable can be null.

Type Parameters:

T - Type of the elements of the array.

Parameters:

array - Input array. Can be null.

Returns:

A reference to the input array if it is not null, an empty array otherwise.