The clear()
method of the WeakHashMap
class in Java removes all key and value mappings from a specified WeakHashMap
object. After this method is called, the WeakHashMap
object becomes empty.
WeakHashMap
is a kind ofMap
implemented based on theHashTable
. TheWeakHashMap
only storesWeakReference
types as their keys. Once the key is no longer used, the respective mapping is automatically removed during garbage collection.
public void clear()
This method doesn’t take any parameters, and does not return a value.
The code below shows how to use the clear()
method.
import java.util.WeakHashMap;class WeakHashMapClearExample {public static void main( String args[] ) {WeakHashMap<String, Integer> map = new WeakHashMap<>();String key = new String("ten");map.put(key, 10);System.out.println("WeakHashMap is : "+ map);map.clear();System.out.println("\nAfter Calling Clear method");System.out.println("\nWeakHashMap is : " + map);}}
In the code above:
We import the WeakHashMap
class.
We create a WeakHashMap
object, and use the put()
method to add one mapping ({ten=10}
) to the map
.
We use the clear()
method to remove all the mappings from map
. This makes the map
empty.
We print the map
to ensure that it is empty.