Package it.unive.lisa.util.collections

Class CollectionUtilities

java.lang.Object

it.unive.lisa.util.collections.CollectionUtilities

public final class CollectionUtilities
extends java.lang.Object

Utility methods for operations on Collections.

Method Summary

Modifier and Type	Method	Description
static <T> java.util.Collection<T>	collect(T... objs)	Stores the given objects into a collection and returns it.
static <T,C extends java.util.Collection<T>> boolean	equals(C first, C second, java.util.function.BiPredicate<T,T> equalityTest)	Tests if two collections contain the same elements, using a custom equality test to determine if two elements are to be considered equals.
static <T,C extends java.util.Collection<T>> void	join(C first, C second, C result, java.util.function.BiPredicate<T,T> equalityTest, java.util.function.BinaryOperator<T> joiner)	Joins (union) two collections, using a custom equality test to determine if two elements are to be considered equals and thus joined together through the given joiner.
static <T> int	nullSafeCompare(boolean nullFirst, T left, T right, java.util.Comparator<T> comparator)	A null-safe comparison callback that invokes the given comparator only if the given objects are both non-null.

Methods inherited from class java.lang.Object

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

Method Detail

nullSafeCompare

public static <T> int nullSafeCompare(boolean nullFirst,
                                      T left,
                                      T right,
                                      java.util.Comparator<T> comparator)

A null-safe comparison callback that invokes the given comparator only if the given objects are both non-null.

Type Parameters:

T - the type of compared objects

Parameters:

nullFirst - if true, null values will be treated as objects that appear before all non-null objects. This means that nullSafeCompare(true, null, obj, ...) returns -1. If false, the same invocation returns 1.

left - the first element to compare

right - the second element to compare

comparator - the comparator to use if both objects are non-null

Returns:

an integer value determined by the ordering relation between objects, as in Comparator.compare(Object, Object)

equals

public static <T,C extends java.util.Collection<T>> boolean equals(C first,
                                                                         C second,
                                                                         java.util.function.BiPredicate<T,T> equalityTest)

Tests if two collections contain the same elements, using a custom equality test to determine if two elements are to be considered equals. The two input collections are compared in an order-insensitive fashion.

Type Parameters:

T - the type of elements in the collections

C - the type of the collections to test

Parameters:

first - the first collection

second - the second collection

equalityTest - the tester for equality of the objects within the collections

Returns:

true only if the collections contain exactly the same set of elements (order-insensitive)

join

public static <T,C extends java.util.Collection<T>> void join(C first,
                                                                    C second,
                                                                    C result,
                                                                    java.util.function.BiPredicate<T,T> equalityTest,
                                                                    java.util.function.BinaryOperator<T> joiner)

Joins (union) two collections, using a custom equality test to determine if two elements are to be considered equals and thus joined together through the given joiner. All elements that, according to the given equalityTest are contained only in one of the input collections, will be added to the result as-is.

Type Parameters:

T - the type of elements in the collections

C - the type of the collections to join

Parameters:

first - the first collection

second - the second collection

result - the collection to be used as result, where joined elements will be added

equalityTest - the tester for equality of the objects within the collections

joiner - the function that computes the join of two equal elements

collect

@SafeVarargs
public static <T> java.util.Collection<T> collect(T... objs)

Stores the given objects into a collection and returns it.

Type Parameters:

T - the type of objects

Parameters:

objs - the objects to store

Returns:

a (modifiable) collection containing the given objects