org.perro.functions.stream

Class StreamUtils

java.lang.Object

org.perro.functions.stream.StreamUtils

public final class StreamUtils
extends java.lang.Object

Methods that are shortcuts to creating streams, specifically methods involving object instances.

Method Summary

Modifier and Type	Method and Description
static <T> boolean	allMatch(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Given a Collection of objects of type <T> and a Predicate, returns a boolean value indicating whether all of the values in the collection match the predicate.
static <T> boolean	anyMatch(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Given a Collection of objects of type <T> and a Predicate, returns a boolean value indicating whether any of the values in the collection match the predicate.
static <T> long	count(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Given a Collection of objects of type <T>, and a Predicate, returns a long value indicating the number of elements in the collection that match the predicate.
static <T> java.util.stream.Stream<T>	defaultStream(java.util.Collection<T> objects) Given a Collection of elements of type <T>, returns a Stream of those elements.
static <T> java.util.stream.Stream<T>	defaultStream(java.util.stream.Stream<T> stream) Given a Stream of elements of type <T>, returns that stream if it is not null, otherwise returns an empty Stream.
static <T> java.util.stream.Stream<T>	defaultStream(T target) Given a single element of type <T>, returns a Stream containing only that element.
static <T> java.util.stream.Stream<T>	defaultStream(T[] array) Given an array of elements of type <T>, returns a Stream of them.
static <T> T	findAnyDefaultNull(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Attempt to find any matching element in a Collection of elements of type <T> using a predicate, returning null if one is not found.
static <T> T	findAnyWithDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefault<T> findWithDefault) Attempt to find any matching element in a Collection of elements of type <T> using a predicate, returning a default element if one is not found.
static <T> T	findAnyWithDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier) Attempt to find any matching element in a Collection of elements of type <T> using a predicate, returning a default value retrieved using a Supplier if one is not found.
static <T> T	findFirstDefaultNull(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Attempt to find the first matching element in a Collection of elements of type <T> using a predicate, returning null if one is not found.
static <T> T	findFirstWithDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefault<T> findWithDefault) Attempt to find the first matching element in a Collection of elements of type <T> using a predicate, returning a default element if one is not found.
static <T> T	findFirstWithDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier) Attempt to find the first matching element in a Collection of elements of type <T> using a predicate, returning a default value retrieved using a Supplier if one is not found.
static <T> org.perro.functions.stream.FindWithDefaultSupplier<T>	findWithDefault(java.util.function.Predicate<T> predicate, java.util.function.Supplier<T> defaultSupplier) Retrieves an object representing a predicate for finding a value, and a default Supplier if one is not found.
static <T> org.perro.functions.stream.FindWithDefault<T>	findWithDefault(java.util.function.Predicate<T> predicate, T defaultValue) Retrieves an object representing a predicate for finding a value, and a default element of type <T> if one is not found.
static <T> java.util.stream.Stream<T>	fromIterator(java.util.Iterator<T> iterator) Given an Iterator of elements of type <T>, returns a Stream of those elements.
static <T> int	indexOfFirst(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Finds the index of the first element in a Collection of type <T>, that matches a Predicate.
static <T> java.lang.String	join(java.util.Collection<T> objects, org.perro.functions.stream.CharSequenceMapperWithCollector<T> mapperWithCollector) Given a Collection of elements of type <T>, and an object representing a Function that takes an element of type <T> and returns a CharSequence, and a joining Collector, this method builds a String of those char sequences joined together using the collector.
static <T> java.lang.String	join(java.util.Collection<T> objects, org.perro.functions.stream.CharSequenceMapperWithDelimiter<T> mapperWithDelimiter) Given a Collection of elements of type <T>, and an object representing a Function that takes an element of type <T> and returns a CharSequence, and a delimiter, this method builds a String of those char sequences joined together using the delimiter.
static <T> java.lang.String	join(java.util.Collection<T> objects, java.util.function.Function<T,java.lang.CharSequence> mapper) Given a Collection of elements of type <T>, and a Function that takes an element of type <T> and returns a CharSequence, this method builds a String of those char sequences joined together using "," as a delimiter.
static <T> org.perro.functions.stream.CharSequenceMapperWithCollector<T>	mapperWithCollector(java.util.function.Function<T,java.lang.CharSequence> charSequenceMapper, java.util.stream.Collector<java.lang.CharSequence,?,java.lang.String> joiner) Builds an object representing a Function that takes an element of type <T> and returns a CharSequence, and a joining Collector.
static <T> org.perro.functions.stream.CharSequenceMapperWithDelimiter<T>	mapperWithDelimiter(java.util.function.Function<T,java.lang.CharSequence> charSequenceMapper, java.lang.CharSequence delimiter) Builds an object representing a Function that takes an element of type <T> and returns a CharSequence, and a delimiter.
static <T extends java.lang.Comparable<T>> T	maxDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefault<T> findWithDefault) Given a Collection of elements of type <T>, and an object representing a Predicate along with a default value of type <T>, this method returns the maximum element in the Collection that matches the predicate, or the default value if no matching element is found.
static <T extends java.lang.Comparable<T>> T	maxDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier) Given a Collection of elements of type <T>, and an object representing a Predicate along with a Supplier for a default value, this method returns the maximum element in the Collection that matches the predicate, or a default value from the supplier if no matching element is found.
static <T extends java.lang.Comparable<T>> T	maxDefaultNull(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Given a Collection of elements of type <T> and a Predicate, this method returns the maximum element in the collection that matches the predicate, returning null if none are found.
static <T extends java.lang.Comparable<T>> T	minDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefault<T> findWithDefault) Given a Collection of elements of type <T>, and an object representing a Predicate along with a default value of type <T>, this method returns the minimum element in the Collection that matches the predicate, or the default value if no matching element is found.
static <T extends java.lang.Comparable<T>> T	minDefault(java.util.Collection<T> objects, org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier) Given a Collection of elements of type <T>, and an object representing a Predicate along with a Supplier for a default value, this method returns the minimum element in the Collection that matches the predicate, or a default value from the supplier if no matching element is found.
static <T extends java.lang.Comparable<T>> T	minDefaultNull(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Given a Collection of elements of type <T> and a Predicate, this method returns the minimum element in the collection that matches the predicate, returning null if none are found.
static <T> boolean	noneMatch(java.util.Collection<T> objects, java.util.function.Predicate<T> predicate) Given a Collection of objects of type <T> and a Predicate, returns a boolean value indicating whether none of the values in the collection match the predicate.
static <T> java.util.Set<T>	subtract(java.util.Set<T> from, java.util.Set<T> toSubtract) Given a Set from which to subtract the elements of another one, returns a Set of the remaining elements.
static <T> java.util.List<java.util.List<T>>	toPartitionedList(java.util.Collection<T> objects, int partitionSize) Given a Collection of elements of type <T>, and a partition size, this method divides the collection into a List of lists, each of whose length is at most partitionSize.
static <T> java.util.stream.Stream<java.util.List<T>>	toPartitionedStream(java.util.Collection<T> objects, int partitionSize) Given a Collection of elements of type <T>, and a partition size, this method divides the collection into a Stream of lists, each of whose length is at most partitionSize.

Methods inherited from class java.lang.Object

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

Method Detail

allMatch

public static <T> boolean allMatch(java.util.Collection<T> objects,
                                   java.util.function.Predicate<T> predicate)

Given a Collection of objects of type <T> and a Predicate, returns a boolean value indicating whether all of the values in the collection match the predicate.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of objects of type <T>, to be checked whether the given Predicate matches all of its elements.

predicate - A Predicate to match against the elements in the input Collection.

Returns:

A boolean indication of whether all of the elements in a given Collection match a given predicate.

anyMatch

public static <T> boolean anyMatch(java.util.Collection<T> objects,
                                   java.util.function.Predicate<T> predicate)

Given a Collection of objects of type <T> and a Predicate, returns a boolean value indicating whether any of the values in the collection match the predicate.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of objects of type <T>, to be checked whether the given Predicate matches any of its elements.

predicate - A Predicate to match against the elements in the input Collection.

Returns:

A boolean indication of whether any of the elements in a given Collection match a given predicate.

noneMatch

public static <T> boolean noneMatch(java.util.Collection<T> objects,
                                    java.util.function.Predicate<T> predicate)

Given a Collection of objects of type <T> and a Predicate, returns a boolean value indicating whether none of the values in the collection match the predicate.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of objects of type <T>, to be checked whether the given Predicate matches none of its elements.

predicate - A Predicate to match against the elements in the input Collection.

Returns:

A boolean indication of whether none of the elements in a given Collection match a given predicate.

count

public static <T> long count(java.util.Collection<T> objects,
                             java.util.function.Predicate<T> predicate)

Given a Collection of objects of type <T>, and a Predicate, returns a long value indicating the number of elements in the collection that match the predicate.

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of objects of type <T>, to be counted for the number of them that match the given Predicate.

predicate - A Predicate to match against the values in the input array.

Returns:

A long value indicating the number of elements in a given Collection that match a given predicate.

maxDefaultNull

public static <T extends java.lang.Comparable<T>> T maxDefaultNull(java.util.Collection<T> objects,
                                                                   java.util.function.Predicate<T> predicate)

Given a Collection of elements of type <T> and a Predicate, this method returns the maximum element in the collection that matches the predicate, returning null if none are found. Note that <T> must extend Comparable.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of elements of type <T> from which to get the maximum element.

predicate - A Predicate to match against the elements in the input Collection.

Returns:

The maximum element of type <T> in the input Collection that matches the given predicate, or null if the Collection is null or empty, or if no elements in it match the predicate.

maxDefault

public static <T extends java.lang.Comparable<T>> T maxDefault(java.util.Collection<T> objects,
                                                               org.perro.functions.stream.FindWithDefault<T> findWithDefault)

Given a Collection of elements of type <T>, and an object representing a Predicate along with a default value of type <T>, this method returns the maximum element in the Collection that matches the predicate, or the default value if no matching element is found. Note that <T> must extend Comparable.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of elements of type <T> from which to get the maximum element or the default value in the given findWithDefault object.

findWithDefault - An object representing a Predicate along with a default value of type <T>.

Returns:

The maximum element of type <T> in the input Collection that matches the given predicate, or the default value if the Collection is null or empty, or if no values in it match the predicate.

maxDefault

public static <T extends java.lang.Comparable<T>> T maxDefault(java.util.Collection<T> objects,
                                                               org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier)

Given a Collection of elements of type <T>, and an object representing a Predicate along with a Supplier for a default value, this method returns the maximum element in the Collection that matches the predicate, or a default value from the supplier if no matching element is found.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of elements of type <T> from which to get the maximum element or the default value from the supplier in the given findWithDefaultSupplier object.

findWithDefaultSupplier - An object representing a Predicate along with a Supplier of a default value.

Returns:

The maximum element of type <T> in the input Collection that matches the predicate, or the default value from the supplier if the Collection is null or empty, or if no values in it match the predicate.

minDefaultNull

public static <T extends java.lang.Comparable<T>> T minDefaultNull(java.util.Collection<T> objects,
                                                                   java.util.function.Predicate<T> predicate)

Given a Collection of elements of type <T> and a Predicate, this method returns the minimum element in the collection that matches the predicate, returning null if none are found. Note that <T> must extend Comparable.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of elements of type <T> from which to get the minimum element.

predicate - A Predicate to match against the elements in the input Collection.

Returns:

The minimum element of type <T> in the input Collection that matches the given predicate, or null if the Collection is null or empty, or if no elements in it match the predicate.

minDefault

public static <T extends java.lang.Comparable<T>> T minDefault(java.util.Collection<T> objects,
                                                               org.perro.functions.stream.FindWithDefault<T> findWithDefault)

Given a Collection of elements of type <T>, and an object representing a Predicate along with a default value of type <T>, this method returns the minimum element in the Collection that matches the predicate, or the default value if no matching element is found. Note that <T> must extend Comparable.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of elements of type <T> from which to get the minimum element or the default value in the given findWithDefault object.

findWithDefault - An object representing a Predicate along with a default value of type <T>.

Returns:

The minimum element of type <T> in the input Collection that matches the given predicate, or the default value if the Collection is null or empty, or if no values in it match the predicate.

minDefault

public static <T extends java.lang.Comparable<T>> T minDefault(java.util.Collection<T> objects,
                                                               org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier)

Given a Collection of elements of type <T>, and an object representing a Predicate along with a Supplier for a default value, this method returns the minimum element in the Collection that matches the predicate, or a default value from the supplier if no matching element is found.

Type Parameters:

T - The type of elements in the objects Collection. Extends Comparable.

Parameters:

objects - A Collection of elements of type <T> from which to get the minimum element or the default value from the supplier in the given findWithDefaultSupplier object.

findWithDefaultSupplier - An object representing a Predicate along with a Supplier of a default value.

Returns:

The minimum element of type <T> in the input Collection that matches the predicate, or the default value from the supplier if the Collection is null or empty, or if no values in it match the predicate.

findAnyDefaultNull

public static <T> T findAnyDefaultNull(java.util.Collection<T> objects,
                                       java.util.function.Predicate<T> predicate)

Attempt to find any matching element in a Collection of elements of type <T> using a predicate, returning null if one is not found. Here is a contrived example of how this method would be called - assume WidgetType is an enum representing the type of Widget:

     {
         Collection<Widget> widgets = ...
         return StreamUtils.findAnyDefaultNull(widgets, PredicateUtils.isEqual(WidgetType.PREMIUM, Widget::getType));
     }
 

Or, with static imports:

     {
         Collection<Widget> widgets = ...
         return findAnyDefaultNull(widgets, isEqual(WidgetType.PREMIUM, Widget::getType));
     }
 

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

predicate - A predicate for finding an element of type <T>.

Returns:

An element of type <T> if one is found, otherwise null if the Collection is null or empty, or if no values in it match the predicate.

findAnyWithDefault

public static <T> T findAnyWithDefault(java.util.Collection<T> objects,
                                       org.perro.functions.stream.FindWithDefault<T> findWithDefault)

Attempt to find any matching element in a Collection of elements of type <T> using a predicate, returning a default element if one is not found. Here is a contrived example of how this method would be called:

     {
         Collection<Widget> widgets = ...
         Widget defaultWidget = ...
         return StreamUtils.findAnyWithDefault(widgets, StreamUtils.findWithDefault(PredicateUtils.isEqual(WidgetType.PREMIUM, Widget::getType), defaultWidget));
     }
 

Or, with static imports:

     {
         Collection<Widget> widgets = ...
         Widget defaultWidget = ...
         return findAnyWithDefault(widgets, findWithDefault(isEqual(WidgetType.PREMIUM, Widget::getType), defaultWidget));
     }
 

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

findWithDefault - An object representing a predicate for finding a value, and a default element one is not found. Use the findWithDefault(Predicate, Supplier) to provide this parameter.

Returns:

An element of type <T> if one is found, otherwise the default from findWithDefault if the Collection is null or empty, or if no values in it match the predicate.

findAnyWithDefault

public static <T> T findAnyWithDefault(java.util.Collection<T> objects,
                                       org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier)

Attempt to find any matching element in a Collection of elements of type <T> using a predicate, returning a default value retrieved using a Supplier if one is not found. Here is a contrived example of how this method would be called:

     {
         Collection<Widget> widgets = ...
         return StreamUtils.findAnyWithDefault(widgets, StreamUtils.findWithDefault(PredicateUtils.isEqual(WidgetType.PREMIUM, Widget::getType), Widget::createDefault));
     }
 

Or, with static imports:

     {
         Collection<Widget> widgets = ...
         return findAnyWithDefault(widgets, findWithDefault(isEqual(WidgetType.PREMIUM, Widget::getType), Widget::createDefault));
     }
 

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

findWithDefaultSupplier - An object representing a predicate for finding a value, and a default Supplier if one is not found. Use the findWithDefault(Predicate, Supplier) method to provide this parameter.

Returns:

An element of type <T> if one is found, otherwise a default from the Supplier in findWithDefaultSupplier if the Collection is null or empty, or if no values in it match the predicate.

findFirstDefaultNull

public static <T> T findFirstDefaultNull(java.util.Collection<T> objects,
                                         java.util.function.Predicate<T> predicate)

Attempt to find the first matching element in a Collection of elements of type <T> using a predicate, returning null if one is not found. Here is a contrived example of how this method would be called - assume WidgetType is an enum representing the type of Widget:

     {
         Collection<Widget> widgets = ...
         return StreamUtils.findFirstDefaultNull(widgets, PredicateUtils.isEqual(WidgetType.PREMIUM, Widget::getType));
     }
 

Or, with static imports:

     {
         Collection<Widget> widgets = ...
         return findFirstDefaultNull(widgets, isEqual(WidgetType.PREMIUM, Widget::getType));
     }
 

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

predicate - A predicate for finding an element of type <T>.

Returns:

The first matching element of type <T> if one is found, otherwise null if the Collection is null or empty, or if no values in it match the predicate.

findFirstWithDefault

public static <T> T findFirstWithDefault(java.util.Collection<T> objects,
                                         org.perro.functions.stream.FindWithDefault<T> findWithDefault)

Attempt to find the first matching element in a Collection of elements of type <T> using a predicate, returning a default element if one is not found. Here is a contrived example of how this method would be called:

     {
         Collection<Widget> widgets = ...
         Widget defaultWidget = ...
         return StreamUtils.findFirstWithDefault(widgets, StreamUtils.findWithDefault(PredicateUtils.isEqual(WidgetType.PREMIUM, Widget::getType), defaultWidget));
     }
 

Or, with static imports:

     {
         Collection<Widget> widgets = ...
         Widget defaultWidget = ...
         return findFirstWithDefault(widgets, findWithDefault(isEqual(WidgetType.PREMIUM, Widget::getType), defaultWidget));
     }
 

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

findWithDefault - An object representing a predicate for finding a value, and a default element one is not found. Use the findWithDefault(Predicate, Supplier) to provide this parameter.

Returns:

The first matching element of type <T> if one is found, otherwise the default from findWithDefault if the Collection is null or empty, or if no values in it match the predicate.

findFirstWithDefault

public static <T> T findFirstWithDefault(java.util.Collection<T> objects,
                                         org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefaultSupplier)

Attempt to find the first matching element in a Collection of elements of type <T> using a predicate, returning a default value retrieved using a Supplier if one is not found. Here is a contrived example of how this method would be called:

     {
         Collection<Widget> widgets = ...
         return StreamUtils.findFirstWithDefault(widgets, StreamUtils.findWithDefault(PredicateUtils.isEqual(WidgetType.PREMIUM, Widget::getType), Widget::createDefault));
     }
 

Or, with static imports:

     {
         Collection<Widget> widgets = ...
         return findFirstWithDefault(widgets, findWithDefault(isEqual(WidgetType.PREMIUM, Widget::getType), Widget::createDefault));
     }
 

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

findWithDefaultSupplier - An object representing a predicate for finding a value, and a default Supplier if one is not found. Use the findWithDefault(Predicate, Supplier) method to provide this parameter.

Returns:

The first matching element of type <T> if one is found, otherwise a default from the Supplier in findWithDefaultSupplier if the Collection is null or empty, or if no values in it match the predicate.

findWithDefault

public static <T> org.perro.functions.stream.FindWithDefault<T> findWithDefault(java.util.function.Predicate<T> predicate,
                                                                                T defaultValue)

Retrieves an object representing a predicate for finding a value, and a default element of type <T> if one is not found. See findAnyWithDefault(Collection, FindWithDefault) or findFirstWithDefault(Collection, FindWithDefault) for usage examples.

Type Parameters:

T - The type of elements taken by the given Predicate. Also, the type of the defaultValue.

Parameters:

predicate - A predicate used in finding a particular element of type <T>.

defaultValue - A default element of type <T> to return if one could not be found using the above predicate.

Returns:

An object containing a predicate and default element of type <T>.

findWithDefault

public static <T> org.perro.functions.stream.FindWithDefaultSupplier<T> findWithDefault(java.util.function.Predicate<T> predicate,
                                                                                        java.util.function.Supplier<T> defaultSupplier)

Retrieves an object representing a predicate for finding a value, and a default Supplier if one is not found. See findAnyWithDefault(Collection, FindWithDefaultSupplier) or findFirstWithDefault(Collection, FindWithDefaultSupplier) for usage examples.

Type Parameters:

T - The type of elements taken by the given Predicate. Also, the return type of the defaultSupplier.

Parameters:

predicate - A predicate used in finding a particular double value.

defaultSupplier - A default DoubleSupplier used to return if one could not be found using the above predicate.

Returns:

An object containing a predicate and default Supplier returning an object of type <T>.

indexOfFirst

public static <T> int indexOfFirst(java.util.Collection<T> objects,
                                   java.util.function.Predicate<T> predicate)

Finds the index of the first element in a Collection of type <T>, that matches a Predicate.

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>.

predicate - A Predicate used to find a matching value.

Returns:

An index of the first value in the given objects Collection matching the predicate. Returns -1 if no matches are found.

join

public static <T> java.lang.String join(java.util.Collection<T> objects,
                                        java.util.function.Function<T,java.lang.CharSequence> mapper)

Given a Collection of elements of type <T>, and a Function that takes an element of type <T> and returns a CharSequence, this method builds a String of those char sequences joined together using "," as a delimiter.

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>, each of which is to be mapped to a CharSequence. A String will be built using each individual CharSequence, delimited by ",".

mapper - A Function to map each element of type <T> to a CharSequence.

Returns:

A String built by mapping each element of type <T> to a CharSequence, and joining them together using "," as a delimiter.

join

public static <T> java.lang.String join(java.util.Collection<T> objects,
                                        org.perro.functions.stream.CharSequenceMapperWithDelimiter<T> mapperWithDelimiter)

Given a Collection of elements of type <T>, and an object representing a Function that takes an element of type <T> and returns a CharSequence, and a delimiter, this method builds a String of those char sequences joined together using the delimiter.

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>, each of which is to be mapped to a CharSequence. A String will be built using each individual CharSequence.

mapperWithDelimiter - An object representing a Function that takes an element of type <T> and returns a CharSequence, and a delimiter.

Returns:

A String built by mapping each element of type <T> to a CharSequence, and joining them together using the delimiter from mapperWithDelimiter.

join

public static <T> java.lang.String join(java.util.Collection<T> objects,
                                        org.perro.functions.stream.CharSequenceMapperWithCollector<T> mapperWithCollector)

Given a Collection of elements of type <T>, and an object representing a Function that takes an element of type <T> and returns a CharSequence, and a joining Collector, this method builds a String of those char sequences joined together using the collector. The mapperWithCollector(Function, Collector) should be used to build the second parameter to this method. Because that method takes a Collector<CharSequence, ?, String>, the overloads of the Java Collector.joining(...) method may be used, including the one that takes a delimiter, prefix and suffix.

Type Parameters:

T - The type of elements in the objects Collection.

Parameters:

objects - A Collection of elements of type <T>, each of which is to be mapped to a CharSequence. A String will be built using each individual CharSequence.

mapperWithCollector - An object representing a Function that takes an element of type <T> and returns a CharSequence, and a Collector used to join the individual char sequences together.

Returns:

A String built by mapping each element of type <T> to a CharSequence, and joining them together using the Collector from mapperWithCollector.

mapperWithDelimiter

public static <T> org.perro.functions.stream.CharSequenceMapperWithDelimiter<T> mapperWithDelimiter(java.util.function.Function<T,java.lang.CharSequence> charSequenceMapper,
                                                                                                    java.lang.CharSequence delimiter)

Builds an object representing a Function that takes an element of type <T> and returns a CharSequence, and a delimiter. Used to build the second parameter to the join(Collection, CharSequenceMapperWithDelimiter) method.

Type Parameters:

T - The type of elements taken by the given Function.

Parameters:

charSequenceMapper - A Function that takes an element of type <T> and returns a CharSequence.

delimiter - A delimiter used to join individual char sequences together.

Returns:

An object representing a Function that takes an element of type <T> and returns a CharSequence, along with a delimiter for joining the char sequences together.

mapperWithCollector

public static <T> org.perro.functions.stream.CharSequenceMapperWithCollector<T> mapperWithCollector(java.util.function.Function<T,java.lang.CharSequence> charSequenceMapper,
                                                                                                    java.util.stream.Collector<java.lang.CharSequence,?,java.lang.String> joiner)

Builds an object representing a Function that takes an element of type <T> and returns a CharSequence, and a joining Collector. Used to build the second parameter to the join(Collection, CharSequenceMapperWithCollector) method.

Type Parameters:

T - The type of elements taken by the given Function.

Parameters:

charSequenceMapper - A Function that takes an element of type <T> and returns a CharSequence.

joiner - A joining Collector used to join individual char sequences together.

Returns:

An object representing a Function that takes an element of type <T> and returns a CharSequence, along with a joining Collector used to join individual char sequences together.

subtract

public static <T> java.util.Set<T> subtract(java.util.Set<T> from,
                                            java.util.Set<T> toSubtract)

Given a Set from which to subtract the elements of another one, returns a Set of the remaining elements. More formally, elements o in the toSubtract set are removed from the from set if (o==null ? e==null : o.equals(e)) where e is an element in from.

Type Parameters:

T - The type of elements in the from and toSubtract sets.

Parameters:

from - A source set from which to subtract elements.

toSubtract - A set of elements to be subtracted from a source set.

Returns:

A set of elements remaining, after subtracting the elements of toSubtract that are contained in from.

toPartitionedList

public static <T> java.util.List<java.util.List<T>> toPartitionedList(java.util.Collection<T> objects,
                                                                      int partitionSize)

Given a Collection of elements of type <T>, and a partition size, this method divides the collection into a List of lists, each of whose length is at most partitionSize.

Type Parameters:

T - The type of the elements in the objects parameter.

Parameters:

objects - A Collection of elements of type <T> to be partitioned up into a list of lists.

partitionSize - The maximum length of the individual lists in the returned list.

Returns:

A List of lists of elements of type <T>, each of whose length is at most partitionSize. The last list may have a length that is less than partitionSize.

toPartitionedStream

public static <T> java.util.stream.Stream<java.util.List<T>> toPartitionedStream(java.util.Collection<T> objects,
                                                                                 int partitionSize)

Given a Collection of elements of type <T>, and a partition size, this method divides the collection into a Stream of lists, each of whose length is at most partitionSize.

Type Parameters:

T - The type of the elements in the objects parameter.

Parameters:

objects - A Collection of elements of type <T> to be partitioned up into a stream of lists.

partitionSize - The maximum length of the individual lists in the returned stream.

Returns:

A stream of lists of elements of type <T>, each of whose length is at most partitionSize. The last list may have a length that is less than partitionSize.

fromIterator

public static <T> java.util.stream.Stream<T> fromIterator(java.util.Iterator<T> iterator)

Given an Iterator of elements of type <T>, returns a Stream of those elements.

Type Parameters:

T - The type of elements iterated by the above iterator.

Parameters:

iterator - An Iterator of elements of type <T>.

Returns:

A Stream of elements of type <T>.

defaultStream

public static <T> java.util.stream.Stream<T> defaultStream(java.util.Collection<T> objects)

Given a Collection of elements of type <T>, returns a Stream of those elements.

Type Parameters:

T - The type of the elements in the objects parameter. Also, the type of the elements in the returned Stream.

Parameters:

objects - A Collection of elements of type <T> from which to return a Stream.

Returns:

A Stream from the given Collection of elements of type <T>. Returns an empty Stream if it is null.

defaultStream

public static <T> java.util.stream.Stream<T> defaultStream(java.util.stream.Stream<T> stream)

Given a Stream of elements of type <T>, returns that stream if it is not null, otherwise returns an empty Stream.

Type Parameters:

T - The type of the elements in the objects parameter. Also, the type of the elements in the returned Stream.

Parameters:

stream - An input Stream.

Returns:

The given Stream if it is not null, otherwise an empty Stream.

defaultStream

public static <T> java.util.stream.Stream<T> defaultStream(T[] array)

Given an array of elements of type <T>, returns a Stream of them.

Type Parameters:

T - The type of the elements in the array parameter. Also, the type of the elements in the returned Stream.

Parameters:

array - An array of elements of type <T>.

Returns:

A Stream from the given array. Returns an empty Stream if it is null.

defaultStream

public static <T> java.util.stream.Stream<T> defaultStream(T target)

Given a single element of type <T>, returns a Stream containing only that element.

Type Parameters:

T - The type of the target element.

Parameters:

target - A single element of type <T>.

Returns:

A Stream containing the given target element. Returns an empty Stream if it is null.