Class Pair<L,R>
- java.lang.Object
-
- org.apache.commons.lang3.tuple.Pair<L,R>
-
- Type Parameters:
L
- the left element typeR
- the right element type
- All Implemented Interfaces:
java.io.Serializable
,java.lang.Comparable<Pair<L,R>>
,java.util.Map.Entry<L,R>
- Direct Known Subclasses:
Diff
,ImmutablePair
,MutablePair
public abstract class Pair<L,R> extends java.lang.Object implements java.util.Map.Entry<L,R>, java.lang.Comparable<Pair<L,R>>, java.io.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:
- 3.0
- See Also:
- Serialized Form
-
-
Field Summary
Fields Modifier and Type Field Description static Pair<?,?>[]
EMPTY_ARRAY
An empty array.
-
Constructor Summary
Constructors Constructor Description Pair()
-
Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description int
compareTo(Pair<L,R> other)
Compares the pair based on the left element followed by the right element.static <L,R>
Pair<L,R>[]emptyArray()
Returns the empty array singleton that can be assigned without compiler warning.boolean
equals(java.lang.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(java.util.Map.Entry<L,R> pair)
Creates an immutable pair from an existing pair.static <L,R>
Pair<L,R>of(L left, R right)
Creates an immutable pair of two objects inferring the generic types.java.lang.String
toString()
Returns a String representation of this pair using the format($left,$right)
.java.lang.String
toString(java.lang.String format)
Formats the receiver using the given format.
-
-
-
Field Detail
-
EMPTY_ARRAY
public static final Pair<?,?>[] EMPTY_ARRAY
An empty array.Consider using
emptyArray()
to avoid generics warnings.- Since:
- 3.10.
-
-
Method Detail
-
emptyArray
public static <L,R> Pair<L,R>[] emptyArray()
Returns the empty array singleton that can be assigned without compiler warning.- Type Parameters:
L
- the left element typeR
- the right element type- Returns:
- the empty array singleton that can be assigned without compiler warning.
- Since:
- 3.10.
-
of
public static <L,R> Pair<L,R> of(L left, R right)
Creates an immutable pair of 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 typeR
- the right element type- Parameters:
left
- the left element, may be nullright
- the right element, may be null- Returns:
- a pair formed from the two parameters, not null
-
of
public static <L,R> Pair<L,R> of(java.util.Map.Entry<L,R> pair)
Creates an immutable pair from an existing pair.
This factory allows the pair to be created using inference to obtain the generic types.
- Type Parameters:
L
- the left element typeR
- the right element type- Parameters:
pair
- the existing pair.- Returns:
- a pair formed from the two parameters, not null
- Since:
- 3.10
-
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 interfacejava.lang.Comparable<L>
- Parameters:
other
- the other pair, not null- Returns:
- negative if this is less, zero if equal, positive if greater
-
equals
public boolean equals(java.lang.Object obj)
Compares this pair to another based on the two elements.
-
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.
-
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
-
getValue
public R getValue()
Gets the value from this pair.
This method implements the
Map.Entry
interface returning the right element as the value.
-
hashCode
public int hashCode()
Returns a suitable hash code. The hash code follows the definition in
Map.Entry
.
-
toString
public java.lang.String toString()
Returns a String representation of this pair using the format
($left,$right)
.- Overrides:
toString
in classjava.lang.Object
- Returns:
- a string describing this object, not null
-
toString
public java.lang.String toString(java.lang.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 bytoString()
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
-
-