ConcurrentHashMap contains() method in Java with Examples
Last Updated : 30 Oct, 2018
The
contains() method of
Java.util.ConcurrentHashMap is used to check whether if some key maps into the specified value in this table. It is a legacy method of performing a particular task. The operation is similar to containsValue() Method of ConcurrentHashMap.
Syntax: ConcurrentHashMap.contains(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 ConcurrentHashMap.containsValue() Method:
Program 1: Mapping String Values to Integer Keys.
Java // Java code to illustrate the contains() method import java.util.*; import java.util.concurrent.*; public class ConcurrentHashMapDemo { public static void main(String[] args) { // Creating an empty HashMap ConcurrentHashMap<Integer, String> hash_map = new ConcurrentHashMap<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 ConcurrentHashMap 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 // Java code to illustrate the contains() method import java.util.*; import java.util.concurrent.*; public class ConcurrentHashMapDemo { public static void main(String[] args) { // Creating an empty ConcurrentHashMap ConcurrentHashMap<String, Integer> hash_map = new ConcurrentHashMap<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 ConcurrentHashMap System.out.println("Initial Mappings are: " + hash_map); // Checking for the Value 'Geeks' System.out.println("Is the value 'Geeks' present? " + hash_map.contains(25)); // Checking for the Value 'World' System.out.println("Is the value 'World' present? " + hash_map.contains(35)); } } Output: Initial Mappings are: {4=15, Geeks=20, You=30, Welcomes=25} Is the value 'Geeks' present? true Is the value 'World' present? false Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.
Explore
Java Basics
OOP & Interfaces
Collections
Exception Handling
Java Advanced
Practice Java
My Profile