com.opengamma.strata.collect.tuple

Class Pair<A,B>

java.lang.Object

com.opengamma.strata.collect.tuple.Pair<A,B>

Type Parameters:

A - the first element type

B - the second element type

All Implemented Interfaces:

Tuple, Serializable, Comparable<Pair<A,B>>, org.joda.beans.Bean, org.joda.beans.ImmutableBean

public final class Pair<A,B>
extends Object
implements org.joda.beans.ImmutableBean, Tuple, Comparable<Pair<A,B>>, Serializable

An immutable pair consisting of two elements.

This implementation refers to the elements as 'first' and 'second'. The elements cannot be null.

Although the implementation is immutable, there is no restriction on the objects that may be stored. If mutable objects are stored in the pair, then the pair itself effectively becomes mutable.

Some primitive specializations of this class are provided, such as DoublesPair.

This class is immutable and thread-safe if the stored objects are immutable.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Pair.Meta<A,B> The meta-bean for Pair.

Method Summary

Modifier and Type	Method and Description
<C,D> Pair<A,B>	combinedWith(Pair<C,D> other, BiFunction<? super A,? super C,? extends A> combinerFirst, BiFunction<? super B,? super D,? extends B> combinerSecond) Combines this instance with another.
static <A,B> BinaryOperator<Pair<A,B>>	combining(BiFunction<? super A,? super A,? extends A> combinerFirst, BiFunction<? super B,? super B,? extends B> combinerSecond) Returns a combiner of pair instances.
int	compareTo(Pair<A,B> other) Compares the pair based on the first element followed by the second element.
ImmutableList<Object>	elements() Gets the elements from this pair as a list.
boolean	equals(Object obj)
A	getFirst() Gets the first element in this pair.
B	getSecond() Gets the second element in this pair.
int	hashCode()
static Pair.Meta	meta() The meta-bean for Pair.
Pair.Meta<A,B>	metaBean()
static <R,S> Pair.Meta<R,S>	metaPair(Class<R> cls1, Class<S> cls2) The meta-bean for Pair.
static <A,B> Pair<A,B>	of(A first, B second) Obtains a pair inferring the types.
int	size() Gets the number of elements held by this pair.
String	toString() Gets the pair using a standard string format.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.joda.beans.Bean

property, propertyNames

Method Detail

of

public static <A,B> Pair<A,B> of(A first,
                                 B second)

Obtains a pair inferring the types.

Type Parameters:

A - the first element type

B - the second element type

Parameters:

first - the first element

second - the second element

Returns:

a pair formed from the two parameters

combining

public static <A,B> BinaryOperator<Pair<A,B>> combining(BiFunction<? super A,? super A,? extends A> combinerFirst,
                                                        BiFunction<? super B,? super B,? extends B> combinerSecond)

Returns a combiner of pair instances.

This is useful if you have a stream of Pair<A, B> and would like to reduce.

e.g

 pairList.stream()
     .reduce(Pair.combining(A::combinedWith, B::combinedWith))
 

Type Parameters:

A - the type of the first values

B - the type of the second values

Parameters:

combinerFirst - the combiner of first values

combinerSecond - the combiner of second values

Returns:

the combiner of pair instance

combinedWith

public <C,D> Pair<A,B> combinedWith(Pair<C,D> other,
                                    BiFunction<? super A,? super C,? extends A> combinerFirst,
                                    BiFunction<? super B,? super D,? extends B> combinerSecond)

Combines this instance with another.

Type Parameters:

C - the type of the first value in the other instance

D - the type of the second value in the other instance

Parameters:

other - the other pair

combinerFirst - the combiner of first values

combinerSecond - the combiner of second values

Returns:

the combined pair instance

size

public int size()

Gets the number of elements held by this pair.

Specified by:

size in interface Tuple

Returns:

size 2

elements

public ImmutableList<Object> elements()

Gets the elements from this pair as a list.

The list returns each element in the pair in order.

Specified by:

elements in interface Tuple

Returns:

the elements as an immutable list

compareTo

public int compareTo(Pair<A,B> other)

Compares the pair based on the first element followed by the second element.

The element types must be Comparable.

Specified by:

compareTo in interface Comparable<Pair<A,B>>

Parameters:

other - the other pair

Returns:

negative if this is less, zero if equal, positive if greater

Throws:

ClassCastException - if either object is not comparable

toString

public String toString()

Gets the pair using a standard string format.

The standard format is '[$first, $second]'. Spaces around the values are trimmed.

Overrides:

toString in class Object

Returns:

the pair as a string

meta

public static Pair.Meta meta()

The meta-bean for Pair.

Returns:

the meta-bean, not null

metaPair

public static <R,S> Pair.Meta<R,S> metaPair(Class<R> cls1,
                                            Class<S> cls2)

The meta-bean for Pair.

Type Parameters:

R - the first generic type

S - the second generic type

Parameters:

cls1 - the first generic type

cls2 - the second generic type

Returns:

the meta-bean, not null

metaBean

public Pair.Meta<A,B> metaBean()

Specified by:

metaBean in interface org.joda.beans.Bean

getFirst

public A getFirst()

Gets the first element in this pair.

Returns:

the value of the property, not null

getSecond

public B getSecond()

Gets the second element in this pair.

Returns:

the value of the property, not null

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object