Pair (Apache Commons Lang 3.4 API)

java.lang.Object
- org.apache.commons.lang3.tuple.Pair<L,R>

Type Parameters:
L - the left element type
R - the right element type

All Implemented Interfaces:

Serializable, Comparable<Pair<L,R>>, Map.Entry<L,R>

Direct Known Subclasses:

Diff, ImmutablePair, MutablePair
```
public abstract class Pair<L,R>
extends Object
implements Map.Entry<L,R>, Comparable<Pair<L,R>>, Serializable
```
A pair consisting of two elements.

This class is an abstract implementation defining the basic API. It refers to the elements as 'left' and 'right'. It also implements the Map.Entry interface where the key is 'left' and the value is 'right'.

Subclass implementations may be mutable or immutable. However, there is no restriction on the type of the stored objects that may be stored. If mutable objects are stored in the pair, then the pair itself effectively becomes mutable.

Since:

Lang 3.0

Version:

$Id: Pair.java 1557584 2014-01-12 18:26:49Z britter $

See Also:
Serialized Form

Constructor Summary

Constructors
Constructor and Description

Pair()

Constructors
Constructor and Description
`Pair()`

Method Summary

Methods
Modifier and Type	Method and Description
`int`	`compareTo(Pair<L,R> other)` Compares the pair based on the left element followed by the right element.
`boolean`	`equals(Object obj)` Compares this pair to another based on the two elements.
`L`	`getKey()` Gets the key from this pair.
`abstract L`	`getLeft()` Gets the left element from this pair.
`abstract R`	`getRight()` Gets the right element from this pair.
`R`	`getValue()` Gets the value from this pair.
`int`	`hashCode()` Returns a suitable hash code.
`static <L,R> Pair<L,R>`	`of(L left, R right)` Obtains an immutable pair of from two objects inferring the generic types.
`String`	`toString()` Returns a String representation of this pair using the format `($left,$right)`.
`String`	`toString(String format)` Formats the receiver using the given format.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map.Entry
setValue

- Constructor Detail
  - Pair
```
public Pair()
```
- Method Detail
  - of
```
public static <L,R> Pair<L,R> of(L left,
                 R right)
```
    Obtains an immutable pair of from two objects inferring the generic types.
    
    This factory allows the pair to be created using inference to obtain the generic types.
    
    Type Parameters:
    L - the left element type
    R - the right element type
    Parameters:
    left - the left element, may be null
    right - the right element, may be null
    
    Returns:
    a pair formed from the two parameters, not null
  - getLeft
```
public abstract L getLeft()
```
    Gets the left element from this pair.
    
    When treated as a key-value pair, this is the key.
    
    Returns:
    the left element, may be null
  - getRight
```
public abstract R getRight()
```
    Gets the right element from this pair.
    
    When treated as a key-value pair, this is the value.
    
    Returns:
    the right element, may be null
  - getKey
```
public final L getKey()
```
    Gets the key from this pair.
    
    This method implements the Map.Entry interface returning the left element as the key.
    
    Specified by:
    
    getKey in interface Map.Entry<L,R>
    
    Returns:
    the left element as the key, may be null
  - getValue
```
public R getValue()
```
    Gets the value from this pair.
    
    This method implements the Map.Entry interface returning the right element as the value.
    
    Specified by:
    
    getValue in interface Map.Entry<L,R>
    
    Returns:
    the right element as the value, may be null
  - compareTo
```
public int compareTo(Pair<L,R> other)
```
    Compares the pair based on the left element followed by the right element. The types must be Comparable.
    
    Specified by:
    
    compareTo in interface Comparable<Pair<L,R>>
    
    Parameters:
    other - the other pair, not null
    
    Returns:
    negative if this is less, zero if equal, positive if greater
  - equals
```
public boolean equals(Object obj)
```
    Compares this pair to another based on the two elements.
    
    Specified by:
    
    equals in interface Map.Entry<L,R>
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    obj - the object to compare to, null returns false
    
    Returns:
    true if the elements of the pair are equal
  - hashCode
```
public int hashCode()
```
    Returns a suitable hash code. The hash code follows the definition in Map.Entry.
    
    Specified by:
    
    hashCode in interface Map.Entry<L,R>
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    the hash code
  - toString
```
public String toString()
```
    Returns a String representation of this pair using the format ($left,$right).
    
    Overrides:
    
    toString in class Object
    
    Returns:
    a string describing this object, not null
  - toString
```
public String toString(String format)
```
    Formats the receiver using the given format.
    
    This uses Formattable to perform the formatting. Two variables may be used to embed the left and right elements. Use %1$s for the left element (key) and %2$s for the right element (value). The default format used by toString() is (%1$s,%2$s).
    
    Parameters:
    format - the format string, optionally containing %1$s and %2$s, not null
    
    Returns:
    the formatted string, not null

Class Pair<L,R>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map.Entry

Constructor Detail

Pair

Method Detail

of

getLeft

getRight

getKey

getValue

compareTo

equals

hashCode

toString

toString