Core Java - Interview Questions and Answers for 'Iterator' | Search Java Interview Question

Core Java - Interview Questions and Answers for 'Iterator' - 11 question(s) found - Order By Newest

Frequently asked.

Q1. What is an Iterator?

Core Java

^Anonymous

Ans. Iterator is an interface that provides methods to iterate over any Collection.

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Q2. What are few iterator classes provided by Java ?

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info@buggybread.com}

Ans. http://www.buggybread.com/2015/01/java-iterator-classes-and-interfaces.html

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Q3. What are fail-fast Iterators ?

Core Java

^{2016-06-09 09:27:36}

Ans. Fail-fast iterators detect illegal concurrent modification during iteration and fail quickly and cleanly rather than risking arbitrary, non deterministic behavior at an undetermined time in future. Example could be of an Iterator failing if it smells ConcurrentModificationException.

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Q4. Is Iterator a class ?

Ans. No, iterator is an interface that is used to parse through the elements of a Collection

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Q5. How Spliterator in Java 8 different than iterator ?

Core Java

^{2016-11-24 09:44:49}

Ans. Though there are many differences the way internally they both iterates the collections and streams respectively, but the main difference in performance that is achieved by spliterator as it can iterate Streams in Parallel whereas iterator only iterates collections sequentially.

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Q6. Which is better in terms of performance - Iterator or Spliterator ?

Core Java

^{2016-11-24 09:46:26}

Ans. Spliterator has better performance potential than iterators but only if the potential is used. Spliterator can iterate streams in parallel as well as in sequence whereas iterator can only iterate in sequence.

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Q7. What are the cursors available in Java ?

Core Java

^{2017-01-15 14:55:22}

Ans. Enumeration
Iterator
List iterator

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Q8. What is the difference between Enumeration and Iterator ?

Core Java

^{2017-05-07 15:22:08}

Ans. Enumeration can iterate only legacy collections like Vector , HashTable and Stack whereas Iterator can iterate both legacy and non legacy collections.

Enumeration is less safer than Iterator

Enumeration is fail safe whereas Iterator is fail fast

Iterator allows for removal of element while traversal whereas Enumeration doesn't have remove method.

Enumerations were introduced in Java 1 whereas Iterators were introduced with Java 2

Enumerations have methods like hasMoreElements and nextElement whereas Iterators have methods like hasNext, next and remove

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Q9. How can i split a linked list in two parts in java 8?

Core Java

^{2017-10-22 15:00:24}

Ans. This can be done using a Spliterator.

LinkedList list = Arrays.asList("names","numbs","birds","animals");
Spliterator split1 = list.Spliterator();
Spliterator split2 = split1.Spliterator();

Now, the LinkedList is split into split1 and split2.
use split2 first then split1 to check the output.

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Q10. Can we modify a list while iterating it ?

Core Java

^{2018-01-30 18:25:33}

Ans. No,we cannot.I t will give concurrentModificationExceptin error. It can be resolved by using ConcurrentClasses like ConcurrentHashMap,CopyOnWriteArrayList,BlockingQueue etc which are fail-safe and wont give exception.

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Q11. How to write an iterator for an iterator of iterators?

Core Java

^{2019-02-01 12:33:36}

^{This question was recently asked at 'Delphix'.This question is still unanswered. Can you please provide an answer.}

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