org.apache.giraph.utils

Class CollectionUtils

java.lang.Object

org.apache.giraph.utils.CollectionUtils

public class CollectionUtils
extends Object

Helper methods for Collections

Method Summary

Modifier and Type	Method and Description
static <K,V,C extends Collection<V>> C	addConcurrent(K key, C values, ConcurrentMap<K,C> map) If map already has a value associated with the key it adds values to that value, otherwise it will put values to the map.
static <T> boolean	isEqual(Iterable<T> first, Iterable<T> second) Helper method to check if iterables are equal.

Methods inherited from class java.lang.Object

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

Method Detail

addConcurrent

public static <K,V,C extends Collection<V>> C addConcurrent(K key,
                                                            C values,
                                                            ConcurrentMap<K,C> map)

If map already has a value associated with the key it adds values to that value, otherwise it will put values to the map. Do not reuse values.

Type Parameters:

K - Key

V - Value

C - Collection

Parameters:

key - Key under which we are adding values

values - Values we want to add

map - Map which we are adding values to

Returns:

New value associated with the key

isEqual

public static <T> boolean isEqual(Iterable<T> first,
                                  Iterable<T> second)

Helper method to check if iterables are equal. Supports the case where the iterable next() returns a reused object. We do assume that iterator() produces the objects in the same order across repeated calls, if the object doesn't change. This is very expensive (n^2) and should be used for testing only.

Type Parameters:

T - Type to compare

Parameters:

first - First iterable

second - Second iterable

Returns:

True if equal, false otherwise