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HashMap containsValue() Method in Java

  • Difficulty Level : Easy
  • Last Updated : 20 Sep, 2019

The java.util.HashMap.containsValue() method is used to check whether a particular value is being mapped by a single or more than one key in the HashMap. It takes the Value as a parameter and returns True if that value is mapped by any of the key in the map.

Syntax:

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Hash_Map.containsValue(Object Value)

Parameters: The method takes just one parameter Value of Object type and refers to the value whose mapping is supposed to be checked by any key inside the map.

Return Value: The method returns boolean true if the mapping of the value is detected else false.



Below programs are used to illustrate the working of java.util.HashMap.containsValue() Method:
Program 1: Mapping String Values to Integer Keys.




// Java code to illustrate the containsValue() method
import java.util.*;
  
public class Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        HashMap<Integer, String> hash_map = new HashMap<Integer, String>();
  
        // Mapping string values to int keys
        hash_map.put(10, "Geeks");
        hash_map.put(15, "4");
        hash_map.put(20, "Geeks");
        hash_map.put(25, "Welcomes");
        hash_map.put(30, "You");
  
        // Displaying the HashMap
        System.out.println("Initial Mappings are: " + hash_map);
  
        // Checking for the Value 'Geeks'
        System.out.println("Is the value 'Geeks' present? "
        hash_map.containsValue("Geeks"));
  
        // Checking for the Value 'World'
        System.out.println("Is the value 'World' present? "
        hash_map.containsValue("World"));
    }
}
Output:
Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Is the value 'Geeks' present? true
Is the value 'World' present? false

Program 2: Mapping Integer Values to String Keys.




// Java code to illustrate the containsValue() method
import java.util.*;
  
public class Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        HashMap<String, Integer> hash_map = new HashMap<String, Integer>();
  
        // Mapping int values to string keys
        hash_map.put("Geeks", 10);
        hash_map.put("4", 15);
        hash_map.put("Geeks", 20);
        hash_map.put("Welcomes", 25);
        hash_map.put("You", 30);
  
        // Displaying the HashMap
        System.out.println("Initial Mappings are: " + hash_map);
  
        // Checking for the Value '10'
        System.out.println("Is the value '10' present? " +
        hash_map.containsValue(10));
  
        // Checking for the Value '30'
        System.out.println("Is the value '30' present? " +
        hash_map.containsValue(30));
  
        // Checking for the Value '40'
        System.out.println("Is the value '40' present? "
        hash_map.containsValue(40));
    }
}
Output:
Initial Mappings are: {4=15, Geeks=20, You=30, Welcomes=25}
Is the value '10' present? false
Is the value '30' present? true
Is the value '40' present? false


Time Complexity :
O(n)

Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.




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