HashMap containsValue() Method in Java

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:

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.