KeyValue Class in JavaTuples

A KeyValue is a Tuple from JavaTuples library that deals with only 2 elements – a key and a value. Since this KeyValue is a generic class, it can hold any type of value in it.

Since KeyValue is a Tuple, hence it also has all the characteristics of JavaTuples:  

• They are Typesafe
• They are Immutable
• They are Iterable
• They are Serializable
• They are Comparable (implements Comparable<Tuple>)
• They implement equals() and hashCode()
• They also implement toString()

Class Declaration 

public final class KeyValue<A, B> extends Tuple 
           implements IValueKey<A>, IValueValue<B>

Class hierarchy 

Object
  ↳ org.javatuples.Tuple
      ↳ org.javatuples.KeyValue<A, B>

Creating KeyValue Tuple 

• From Constructor:
  Syntax: 

KeyValue<A, B> kv = new KeyValue<A, B>(value1, value2);

Example: 

Output: 

[1, Lazyroar]

• Using with() method: The with() method is a function provided by the JavaTuples library, to instantiate the object with such values.
  Syntax: 

KeyValue<type1, type2> kv = KeyValue.with(value1, value2);

Example: 

Output: 

[1, Lazyroar]

• From other collections: The fromCollection() method is used to create a Tuple from a collection, and fromArray() method is used to create from an array. The collection/array must have the same type as of the Tuple and the number of values in the collection/array must match the Tuple class.
  Syntax: 

KeyValue<type1, type2> kv = KeyValue.fromCollection(collectionWith_2_value);
KeyValue<type1, type2> kv = KeyValue.fromArray(arrayWith_2_value);

Example: 

Output: 

[Lazyroar, A computer portal]
[Lazyroar, A computer portal]

Getting Value

The getValue() and getKey() methods can be used to fetch the value and key respectively in a KeyValue Tuple. 

• getKey():
  Syntax: 

KeyValue<type1, type2> kv = 
    new KeyValue<type1, type2>(value1, value2);

type2 val1 = kv.getKey();

Example: 

Output: 

1

• getValue():
  Syntax: 

KeyValue<type1, type2> kv = 
    new KeyValue<type1, type2>(value1, value2);

type2 val1 = kv.getValue();

Example: 

Output: 

Lazyroar

Setting KeyValue Value

Since the Tuples are immutable, it means that modifying a value at an index is not possible. Hence, JavaTuples offer setKey(value) and setValue(value) which creates a copy of the KeyValue with a new value according to method used, and returns a new KeyValue object.

• setKey():
  Syntax: 

KeyValue<type1, type2> kv = 
    new KeyValue<type1, type2>(value1, value2);

KeyValue<type1, type2> kvNew = kv.setKey(valueNew);

Example: 

Output: 

[10, Lazyroar]

• setValue():
  Syntax: 

KeyValue<type1, type2> kv = 
    new KeyValue<type1, type2>(value1, value2);

KeyValue<type1, type2> kvNew = kv.setValue(valueNew);

Example: 

Output: 

[1, A computer science portal]

Searching in KeyValue

An element can be searched in a tuple with the pre-defined method contains(). It returns a boolean value whether the value is present or not.

Syntax:

KeyValue<type1, type2> kv = 
    new KeyValue<type1, type2>(value1, value2);

boolean res = kv.contains(value2);

Example:

Output:

true
false

Iterating through KeyValue

Since KeyValue implement the Iterable<Object> interface. It means that they can be iterated in the same way as collections or arrays.

Syntax:

KeyValue<type1, type2> kv = 
    new KeyValue<type1, type2>(value1, value2);

for (Object item : kv) {
        ...
}

Example:

Output:

1
Lazyroar