Last Updated : 23 Jul, 2018
The java.util.IdentityHashMap.clear() method in Java is used to clear and remove all of the elements or mappings from a specified map.
Syntax:Identity_HashMap.clear()Parameters:
The method does not accept any parameters.
Return Value:The method does not return any value. Below programs are used to illustrate the working of java.util.IdentityHashMap.clear() Method:
Program 1:Mapping String Values to Integer Keys.
Java
// Java code to illustrate the clear() method
import java.util.*;
public class Identity_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty IdentityHashMap
IdentityHashMap<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);
// Clearing the map using clear()
identity_hash.clear();
// Displaying the final IdentityHashMap
System.out.println("Final Map: "
+ identity_hash);
}
}
Output:
Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
Final Map: {}
Program 2:
Mapping Integer Values to String Keys.
Java
// Java code to illustrate the clear() 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);
// Clearing the map using clear()
identity_hash.clear();
// Displaying the final IdentityHashMap
System.out.println("Final Map: "
+ identity_hash);
}
}
Output:
Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
Final Map: {}
Note:
The same operation can be performed with any type of Mapping with variation and combination of different data types.
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