How iterator works internally in Java?

How does an iterator work in java?

An Iterator is an object that can be used to loop through collections, like ArrayList and HashSet. It is called an “iterator” because “iterating” is the technical term for looping. To use an Iterator, you must import it from the java. util package.

How does a iterator work?

An iterator is an object (like a pointer) that points to an element inside the container. We can use iterators to move through the contents of the container. … The most obvious form of an iterator is a pointer. A pointer can point to elements in an array and can iterate through them using the increment operator (++).

What is use of iterator in java?

Iterator in Java is used to traverse each and every element in the collection. Using it, traverse, obtain each element or you can even remove. ListIterator extends Iterator to allow bidirectional traversal of a list, and the modification of elements.

What is hasNext () in Java?

The hasNext() is a method of Java Scanner class which returns true if this scanner has another token in its input.

Why iterator has remove method?

2 Answers. So it checks for concurrent modifications, removes element using public ArrayList remove method, and increments counter of list modifications so ConcurrentModificationException won’t be thrown at next iteration.

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Can we use iterator in map?

Remember that we cannot iterate over map directly using iterators, because Map interface is not the part of Collection. All maps in Java implements Map interface. There are following types of maps in Java: HashMap.

Is iterator an abstract class?

Iterator is an interface. It is not a class. It is used to iterate through each and every element in a list. Iterator is implemented Iterator design pattern.

Where we can use iterator?

Iterator enables you to cycle through a collection, obtaining or removing elements. ListIterator extends Iterator to allow bidirectional traversal of a list, and the modification of elements. Before you can access a collection through an iterator, you must obtain one.

Should I use iterator Java?

5 Answers. As you have stated iterator is used when you want to remove stuff whilst you iterate over the array contents. If you don’t use an iterator but simply have a for loop and inside it use the remove method you will get exceptions because the contents of the array changes while you iterate through.

Can we iterate HashMap?

There is a numerous number of ways to iterate over HashMap of which 5 are listed as below: Iterate through a HashMap EntrySet using Iterators. Iterate through HashMap KeySet using Iterator. Iterate HashMap using for-each loop.

What is Spliterator in Java?

Java Spliterator interface is an internal iterator that breaks the stream into the smaller parts. … The Java collection classes provide default stream() and parallelStream() methods which internally use the Spliterator through the call to the spliterator(). It helps in processing the collection data in parallel.

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