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() methodimport 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")); }} |
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() methodimport 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)); }} |
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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