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 characterstics 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:

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    // Below is a Java program to create
    // a KeyValue tuple from Constructor
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            KeyValue<Integer, String> kv
                = new KeyValue<Integer, String>(Integer.valueOf(1), "GeeksforGeeks");
      
            System.out.println(kv);
        }
    }

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    Output:

    [1, GeeksforGeeks]
    
  • 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:

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    // Below is a Java program to create
    // a KeyValue tuple from with() method
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            KeyValue<Integer, String> kv
                = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
      
            System.out.println(kv);
        }
    }

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    Output:

    [1, GeeksforGeeks]
    
  • 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:

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    // Below is a Java program to create
    // a KeyValue tuple from Collection
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            // Creating KeyValue from List
            List<String> list = new ArrayList<String>();
            list.add("GeeksforGeeks");
            list.add("A computer portal");
            KeyValue<String, String> kv
                = KeyValue.fromCollection(list);
      
            // Creating KeyValue from Array
            String[] arr = { "GeeksforGeeks", "A computer portal" };
            KeyValue<String, String> otherKeyValue
                = KeyValue.fromArray(arr);
      
            System.out.println(kv);
            System.out.println(otherKeyValue);
        }
    }

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    Output:

    [GeeksforGeeks, A computer portal]
    [GeeksforGeeks, 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:

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    // Below is a Java program to get
    // a KeyValue value
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            KeyValue<Integer, String> kv
                = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
      
            System.out.println(kv.getKey());
        }
    }

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    Output:

    1
    
  • getValue():

    Syntax:

    KeyValue<type1, type2> kv = 
        new KeyValue<type1, type2>(value1, value2);
    
    type2 val1 = kv.getValue();
    

    Example:

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    // Below is a Java program to get
    // a KeyValue value
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            KeyValue<Integer, String> kv
                = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
      
            System.out.println(kv.getValue());
        }
    }

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    Output:

    GeeksforGeeks
    
  • 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:

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      // Below is a Java program to set
      // a KeyValue Key
        
      import java.util.*;
      import org.javatuples.KeyValue;
        
      class GfG {
          public static void main(String[] args)
          {
              KeyValue<Integer, String> kv
                  = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
        
              KeyValue<Integer, String> otherKeyValue
                  = kv.setKey(10);
        
              System.out.println(otherKeyValue);
          }
      }

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      Output:

      [10, GeeksforGeeks]
      
    • setValue():

      Syntax:

      KeyValue<type1, type2> kv = 
          new KeyValue<type1, type2>(value1, value2);
      
      KeyValue<type1, type2> kvNew = kv.setValue(valueNew);
      

      Example:

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      // Below is a Java program to set
      // a KeyValue Value
        
      import java.util.*;
      import org.javatuples.KeyValue;
        
      class GfG {
          public static void main(String[] args)
          {
              KeyValue<Integer, String> kv
                  = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
        
              KeyValue<Integer, String> otherKeyValue
                  = kv.setValue("A computer science portal");
        
              System.out.println(otherKeyValue);
          }
      }

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      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:

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    // Below is a Java program to search
    // a value
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            KeyValue<Integer, String> kv
                = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
      
            // Using contains for True result
            boolean exist = kv.contains("GeeksforGeeks");
      
            // Using contains for False result
            boolean exist1 = kv.contains(4);
      
            System.out.println(exist);
            System.out.println(exist1);
        }
    }

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    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:

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    // Below is a Java program to iterate
    // a KeyValue
      
    import java.util.*;
    import org.javatuples.KeyValue;
      
    class GfG {
        public static void main(String[] args)
        {
            KeyValue<Integer, String> kv
                = KeyValue.with(Integer.valueOf(1), "GeeksforGeeks");
      
            for (Object item : kv)
                System.out.println(item);
        }
    }

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    Output:

    1
    GeeksforGeeks
    




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