What is difference between Enumeration and Iterator in java?
Iterator can do modifications (e.g using remove() method it removes the element from the Collection during traversal). Enumeration interface acts as a read only interface, one can not do any modifications to Collection while traversing the elements of the Collection.
What is Iterator and enumerator in java?
In Iterator, we can read and remove element while traversing element in the collections. Using Enumeration, we can only read element during traversing element in the collections. 2. Access. It can be used with any class of the collection framework.
Which is faster Enumeration or Iterator?
Enumeration is used to traverse the legacy classes like Vector, Stack and HashTable. Iterator is used to iterate most of the classes in the collection framework like ArrayList, HashSet, HashMap, LinkedList etc. Iterator is fail-fast in nature. Enumeration is not safe and secured due to it’s fail-safe nature.
Which of the following is a correct difference between the Iterator and enumerator?
The main difference between Iterator and Enumeration is that Iterator is a universal cursor, can be used for iterating any collection object. On the other hand, the Enumeration is used for traversing object of legacy class only. Enumeration object has only read-only access to the elements in the collection.
Is enumerator fail fast?
3. Fail-fast or Fail-safe : Enumeration is fail-safe in nature. It does not throw ConcurrentModificationException if Collection is modified during the traversal. It throws ConcurrentModificationException if a Collection is modified while iterating other than its own remove() method.
Why ConcurrentHashMap is fail safe?
concurrent package such as ConcurrentHashMap, CopyOnWriteArrayList, etc. are Fail-Safe in nature. In the code snippet above, we’re using Fail-Safe Iterator. Hence, even though a new element is added to the Collection during the iteration, it doesn’t throw an exception.
Is iterator fail fast?
Fail Fast Iterator. The iterator in Java is used to traverse over a collection’s objects. The collections return two types of iterators, either it will be Fail Fast or Fail Safe. The Fail Fast iterators immediately throw ConcurrentModificationException in case of structural modification of the collection.
Why is null not allowed in ConcurrentHashMap?
The main reason that nulls aren’t allowed in ConcurrentMaps (ConcurrentHashMaps, ConcurrentSkipListMaps) is that ambiguities that may be just barely tolerable in non-concurrent maps can’t be accommodated. The main one is that if map. contains(key) , but in a concurrent one, the map might have changed between calls.
What is difference between enumeration and iterator in Java?
Key Differences Between Iterator and Enumeration in Java The main difference between Iterator and Enumeration is that Iterator is a universal cursor, can be used for iterating any collection object. On the other hand, the Enumeration is used for traversing object of legacy class only.
What is difference between iterator and for loop?
An Iterator is an Object, which goes through a Collection and you can do something with whatever the Iterator is pointing at. One big advantage is, that you don’t have to know the size of your Collection. A Loop is a construct, that repeats something for a certain amount of times. One big advantage is, that you always know,…
Is iterator a class or interface?
In Java, Iterator is an interface available in Collection framework in java.util package. It is a Java Cursor used to iterate a collection of objects. It is used to traverse a collection object elements one by one. It is available since Java 1.2 Collection Framework. It is applicable for all Collection classes.
What is the role of iterator in collection framework?
Iterators are used in Collection framework in Java to retrieve elements one by one. There are three iterators. It is a interface used to get elements of legacy collections (Vector, Hashtable).