HashMap containsValue() Method in Java - GeeksforGeeks

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:
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.
Java - util package
Java-Collections
Java-Functions
Java-HashMap
Java
Java
Java-Collections
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