Last Updated : 30 Oct, 2018
The
entrySet()method of
ConcurrentHashMapin Java is used to create a set from the same elements contained in the concurrent hash map. It basically returns a set view of the concurrent hash map or we can create a new set and store the map elements into them.
Syntax:ConcurrentHashMap.entrySet()Parameters:
The method does not take any parameter.
Return Value:The method returns a set having same elements as the concurrent hash map. Below programs are used to illustrate the working of entrySet() Method:
Program 1:Mapping String Values to Integer Keys.
Java
// Java code to illustrate the entrySet() method
import java.util.*;
import java.util.concurrent.*;
public class ConcurrentHashMapDemo {
public static void main(String[] args)
{
// Creating an empty ConcurrentHashMap
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 HashMap
System.out.println("Initial Mappings are: " + hash_map);
// Using entrySet() to get the set view
System.out.println("The set is: " + hash_map.entrySet());
}
}
Output:
Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4} The set is: [20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4]Program 2:
Mapping Integer Values to String Keys.
Java
// Java code to illustrate the entrySet() 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 HashMap
System.out.println("Initial Mappings are: " + hash_map);
// Using entrySet() to get the set viewa
System.out.println("The set is: " + hash_map.entrySet());
}
}
Output:
Initial Mappings are: {4=15, Geeks=20, You=30, Welcomes=25} The set is: [4=15, Geeks=20, You=30, Welcomes=25]Note:
The same operation can be performed with any type of Mappings with variation and combination of different data types.
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