The java.util.WeakHashMap.clear() method in Java is used to clear and remove all of the elements or mappings from a specified map.
Syntax:
Weak_Hash_Map.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.WeakHashMap.clear() Method:
Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the clear() methodimport java.util.*;  public class Weak_Hash_Map_Demo {    public static void main(String[] args)    {          // Creating an empty WeakHashMap        Map<Integer, String> weak_hash = new WeakHashMap<Integer, String>();          // Mapping string values to int keys        weak_hash.put(10, "Geeks");        weak_hash.put(15, "4");        weak_hash.put(20, "Geeks");        weak_hash.put(25, "Welcomes");        weak_hash.put(30, "You");          // Displaying the WeakHashMap        System.out.println("Initial Mappings are: "                           + weak_hash);          // Clearing the map using clear()        weak_hash.clear();          // Displaying the final WeakHashMap        System.out.println("Final Map: "                           + weak_hash);    }} |
Output:
Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
Final Map: {}
Program 2: Mapping Integer Values to String Keys.
// Java code to illustrate the clear() methodimport java.util.*;  public class Weak_Hash_Map_Demo {    public static void main(String[] args)    {          // Creating an empty WeakHashMap        Map<String, Integer> weak_hash = new WeakHashMap<String, Integer>();          // Mapping int values to string keys        weak_hash.put("Geeks", 10);        weak_hash.put("4", 15);        weak_hash.put("Geeks", 20);        weak_hash.put("Welcomes", 25);        weak_hash.put("You", 30);          // Displaying the WeakHashMap        System.out.println("Initial Mappings are: " + weak_hash);          // Clearing the map using clear()        weak_hash.clear();          // Displaying the final WeakHashMap        System.out.println("Final Map: "                           + weak_hash);    }} |
Output:
Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
Final Map: {}
Note: The same operation can be performed with any type of Mapping with variation and combination of different data types.
