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ConcurrentHashMap contains() method in Java with Examples

ConcurrentHashMap computeIfAbsent() method in Java with Examples

ConcurrentHashMap containsKey() Method in Java

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 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, "Beginner");
        hash_map.put(15, "4");
        hash_map.put(20, "Beginner");
        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 'Beginner'
        System.out.println("Is the value 'Beginner' present? "
                           + hash_map.containsValue("Beginner"));
  
        // Checking for the Value 'World'
        System.out.println("Is the value 'World' present? "
                           + hash_map.containsValue("World"));
    }
} 






                        







													
													
												

												
												

													
													

Output:


Initial Mappings are: {20=Beginner, 25=Welcomes, 10=Beginner, 30=You, 15=4}
Is the value 'Beginner' present? true
Is the value 'World' present? false




													
													
												

												
												

													
													
Program 2: Mapping Integer Values to String Keys.

													
													
												

												
												

													
													









                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















// 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("Beginner", 10); 


        hash_map.put("4", 15); 


        hash_map.put("Beginner", 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 'Beginner' 


        System.out.println("Is the value 'Beginner' 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, Beginner=20, You=30, Welcomes=25}
Is the value 'Beginner' 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.

													
													
												

												
												

													
													

													
													
												

												
												

													
													

													
													
												

												
												

													
													

													
													
												

												
													
											

											
										

									

									

										
										
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												ConcurrentHashMap  computeIfAbsent() method in Java with Examples
											
											
										

										

											
											
												ConcurrentHashMap containsKey() Method in Java