Last Updated : 24 Jul, 2018
The java.util.IdentityHashMap.keySet() method in Java is used to create a set out of the key elements contained in the hash map. It basically returns a set view of the keys or we can create a new set and store the key elements in them.
Syntax:Identity_Hash_Map.keySet()Parameters:
The method does not take any parameter.
Return Value:The method returns a set having the keys of the Identity hash map. Below programs are used to illustrate the working of java.util.IdentityHashMap.keySet() Method:
Program 1:Mapping String Values to Integer Keys.
Java
// Java code to illustrate the keySet() method
import java.util.*;
public class Identity_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty IdentityHashMap
Map<Integer, String> Identity_hash = new IdentityHashMap<Integer, String>();
// Mapping string values to int keys
Identity_hash.put(10, "Geeks");
Identity_hash.put(15, "4");
Identity_hash.put(20, "Geeks");
Identity_hash.put(25, "Welcomes");
Identity_hash.put(30, "You");
// Displaying the IdentityHashMap
System.out.println("Initial Mappings are: " + Identity_hash);
// Using keySet() to get the set view of keys
System.out.println("The set is: " + Identity_hash.keySet());
}
}
Output:
Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
The set is: [30, 15, 10, 25, 20]
Program 2:
Mapping Integer Values to String Keys.
Java
// Java code to illustrate the keySet() method
import java.util.*;
public class Identity_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty IdentityHashMap
Map<String, Integer> Identity_hash = new IdentityHashMap<String, Integer>();
// Mapping int values to string keys
Identity_hash.put("Geeks", 10);
Identity_hash.put("4", 15);
Identity_hash.put("Geeks", 20);
Identity_hash.put("Welcomes", 25);
Identity_hash.put("You", 30);
// Displaying the IdentityHashMap
System.out.println("Initial Mappings are: " + Identity_hash);
// Using keySet() to get the set view of keys
System.out.println("The set is: " + Identity_hash.keySet());
}
}
Output:
Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
The set is: [Welcomes, 4, You, Geeks]
Note:
The same operation can be performed with any type of Mappings with variation and combination of different data types.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4