What is the use of WeakHashMap in Java?
WeakHashMap is an implementation of the Map interface that stores only weak references to its keys. Storing only weak references allows a key-value pair to be garbage collected when its key is no longer referenced outside of the WeakHashMap. This class provides the easiest way to harness the power of weak references.
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What is Fail Fast and Fail Safe in Java?
The Java Collection supports two types of iterators; Fail Fast and Fail Safe. These iterators are very useful in handling exceptions. The Fail fast iterator aborts the operation as soon as it exposes the failures and stops the entire operation. Comparatively, the Fail Safe iterator does not cancel the operation on failure.
What is the difference between HashMap and IdentityHashMap in Java?
HashMap uses object equality to compare key and values. IdentityHashMap uses reference equality to compare key and values. HashMap uses the hashCode() method of the HashMap class to find the location of the bucket. IdentityHashMap does not use the hashCode() method but uses System.
ArrayList fails quickly in Java?
The ArrayList’s iterator fails fast, so while iterating over the ArrayList using the Iterator, if the underlying ArrayList is modified by any method other than add and remove provided by the Iterator itself, it will throw a ConcurrentModificationException and be rescued.
Can a weak hash map be garbage collected in Java?
It implements the Map interface. Note: Weak hashmap keys are of type WeakReference. The object of a weak reference type can be garbage collected in Java if the reference is no longer used in the program. Let’s first learn how to create a weak hash map.
What is dominant over the garbage collector in HashMap?
In HashMap, key objects have a strong reference. Garbage Collector Role: Garbage Collection: In HashMap, the input object (the input object stores key-value pairs) is not eligible for garbage collection, i.e. Hashmap is dominant over the garbage collector.
When is an entry removed from a weak hash map?
An entry in a WeakHashMap will automatically be removed when its key is no longer normally used. More precisely, the presence of a mapping for a given key will not prevent the garbage collector from discarding the key, that is, making it finalizable, finalized, and then reclaimed.
How is a key stored in a weak hash map?
Each key object in a WeakHashMap is stored indirectly as the referrer of a weak reference. Thus, a key will be automatically deleted only after the garbage collector has deleted weak references to it, both in and out of the map.