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.
import java.util.*;
import java.util.concurrent.*;
public class ConcurrentHashMapDemo {
public static void main(String[] args)
{
ConcurrentHashMap<Integer, String>
hash_map = new ConcurrentHashMap<Integer,
String>();
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");
System.out.println("Initial Mappings are: "
+ hash_map);
System.out.println("Is the value 'Geeks' present? "
+ hash_map.containsValue("Geeks"));
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.
import java.util.*;
import java.util.concurrent.*;
public class ConcurrentHashMapDemo {
public static void main(String[] args)
{
ConcurrentHashMap<String, Integer>
hash_map = new ConcurrentHashMap<String,
Integer>();
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);
System.out.println("Initial Mappings are: "
+ hash_map);
System.out.println("Is the value 'Geeks' present? "
+ hash_map.contains(25));
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.
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