de.scravy.pair

Class Pairs

java.lang.Object

de.scravy.pair.Pairs

public class Pairs
extends Object

Static methods for dealing with all sorts of pairs.

Since:

1.0.0

Author:

Julian Fleischer

Constructor Summary

Constructors

Constructor and Description
Pairs()

Method Summary

Modifier and Type	Method and Description
static <First extends Comparable<? super First>,Second extends Comparable<? super Second>> int	compare(First firstOfLeft, Second secondOfLeft, First firstOfRight, Second secondOfRight) compare(a, b, c, d) lexicographically compares the pair (a, b) with the pair (c, d).
static <First extends Comparable<? super First>,Second extends Comparable<? super Second>> int	compare(Pair<First,Second> left, Pair<First,Second> right) compare(a, b) lexicographically compares the pair a with the pair b.
static <F,S> boolean	equals(Pair<F,S> left, Object right) Compares two pairs for equality.
static <First,Second> Pair<First,Second>	from(First first, Second second) Create a simple pair from it's first and second component.
static <First extends Comparable<? super First>,Second extends Comparable<? super Second>> ComparablePair<First,Second>	fromComparables(First first, Second second) Creates a pair from comparables which is itself Comparable.
static <First extends Serializable & Comparable<? super First>,Second extends Serializable & Comparable<? super Second>> ComparableSerializablePair<First,Second>	fromComparableSerializables(First first, Second second) Creates a pair from components which are comparable and serializable which is itself Comparable and Serializable.
static <First extends Serializable,Second extends Serializable> SerializablePair<First,Second>	fromSerializables(First first, Second second) Creates a pair from serializables which is itself Serializable.
static <F,S> int	hashCode(Pair<F,S> pair) Computes the hash code of a pair.
static <CommonSuperType,First extends CommonSuperType,Second extends CommonSuperType> CommonSuperType[]	toArray(Pair<First,Second> pair, Class<CommonSuperType> commonSuperType) Transform a pair into an array of the common super type of both components.
static <CommonSuperType,First extends CommonSuperType,Second extends CommonSuperType> CommonSuperType[]	toArray(Pair<First,Second> pair, CommonSuperType[] target, int offset) Write a pair into an array of the common super type of both components.
static <K,V,M extends Map<K,V>> M	toMap(Iterable<Pair<K,V>> pairs, Class<M> mapType) Creates a Map of the given mapType from an Iterable of pairs (k, v).
static <K,V,M extends Map<K,V>> M	toMap(Iterable<Pair<K,V>> pairs, M map) Adds the pairs from the Iterable of pairs (k, v) to the given map.

Methods inherited from class java.lang.Object

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

Constructor Detail

Pairs

public Pairs()

Method Detail

from

public static <First,Second> Pair<First,Second> from(First first,
                                                     Second second)

Create a simple pair from it's first and second component.

Parameters:

first - The first (left) component.

second - The second (right) component.

Returns:

A pair consisting of the two components.

Since:

1.0.0

fromComparables

public static <First extends Comparable<? super First>,Second extends Comparable<? super Second>> ComparablePair<First,Second> fromComparables(First first,
                                                                                                                                               Second second)

Creates a pair from comparables which is itself Comparable.

Parameters:

first - The first (left) component.

second - The second (right) component.

Returns:

A comparable pair consisting of the two components.

Since:

1.0.0

fromSerializables

public static <First extends Serializable,Second extends Serializable> SerializablePair<First,Second> fromSerializables(First first,
                                                                                                                        Second second)

Creates a pair from serializables which is itself Serializable.

Parameters:

first - The first (left) component.

second - The second (right) component.

Returns:

A serilizable pair consisting of the two components.

Since:

1.0.0

fromComparableSerializables

public static <First extends Serializable & Comparable<? super First>,Second extends Serializable & Comparable<? super Second>> ComparableSerializablePair<First,Second> fromComparableSerializables(First first,
                                                                                                                                                                                                     Second second)

Creates a pair from components which are comparable and serializable which is itself Comparable and Serializable.

Parameters:

first - The first (left) component.

second - The second (right) component.

Returns:

A serilizable pair consisting of the two components.

Since:

1.0.0

toArray

public static <CommonSuperType,First extends CommonSuperType,Second extends CommonSuperType> CommonSuperType[] toArray(Pair<First,Second> pair,
                                                                                                                       Class<CommonSuperType> commonSuperType)

Transform a pair into an array of the common super type of both components.

Parameters:

pair - The pair.

commonSuperType - A common super type that both First and Second inherit from.

Returns:

The array of the common super type with length 2.

toArray

public static <CommonSuperType,First extends CommonSuperType,Second extends CommonSuperType> CommonSuperType[] toArray(Pair<First,Second> pair,
                                                                                                                       CommonSuperType[] target,
                                                                                                                       int offset)

Write a pair into an array of the common super type of both components.

Parameters:

pair - The pair.

Returns:

The array of the common super type with length 2.

Since:

1.0.0

compare

public static <First extends Comparable<? super First>,Second extends Comparable<? super Second>> int compare(Pair<First,Second> left,
                                                                                                              Pair<First,Second> right)

compare(a, b) lexicographically compares the pair a with the pair b. If you create your pairs using fromComparables(Comparable, Comparable) you have it Comparable anyhow.

Parameters:

left - The left pair.

right - The right pair.

Returns:

0 if both pairs are the same, a value less then zero if the left pair is lexicographically lesser than the right one, or a value greater than zero.

Since:

1.0.0

compare

public static <First extends Comparable<? super First>,Second extends Comparable<? super Second>> int compare(First firstOfLeft,
                                                                                                              Second secondOfLeft,
                                                                                                              First firstOfRight,
                                                                                                              Second secondOfRight)

compare(a, b, c, d) lexicographically compares the pair (a, b) with the pair (c, d). If you create your pairs using fromComparables(Comparable, Comparable) you have it Comparable anyhow.

Parameters:

firstOfLeft - The first component of the left pair.

secondOfLeft - The second component of the left pair.

firstOfRight - The first component of the right pair.

secondOfRight - The second component of the right pair.

Returns:

0 if both pairs are the same, a value less then zero if the left pair is lexicographically lesser than the right one, or a value greater than zero.

Since:

1.0.0

toMap

public static <K,V,M extends Map<K,V>> M toMap(Iterable<Pair<K,V>> pairs,
                                               Class<M> mapType)

Creates a Map of the given mapType from an Iterable of pairs (k, v).

Parameters:

pairs - The pairs.

mapType - The map type (must have a public default constructor).

Returns:

The map populated with the values from pairs or null, if the Map could not be instantiated.

Since:

1.0.0

toMap

public static <K,V,M extends Map<K,V>> M toMap(Iterable<Pair<K,V>> pairs,
                                               M map)

Adds the pairs from the Iterable of pairs (k, v) to the given map.

Parameters:

pairs - The key/value pairs.

map - The map to add the key/value pairs to.

Returns:

The map.

Throws:

IllegalArgumentException - if the given Map is null.

Since:

1.0.0

equals

public static <F,S> boolean equals(Pair<F,S> left,
                                   Object right)

Compares two pairs for equality.

Type Parameters:

F - The type of the first component.

S - The type of the second component.

Parameters:

left - The left pair.

right - The right pair.

Returns:

Whether the first and the second components of the left and the right pair equal each other. This comparison is done using their native equals methods.

Since:

1.1.0

hashCode

public static <F,S> int hashCode(Pair<F,S> pair)

Computes the hash code of a pair.

Type Parameters:

F - The type of the first component.

S - The type of the second component.

Parameters:

pair - The pair.

Returns:

The hash code of that pair.

Since:

1.1.0