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This article mainly introduces "the similarities and differences between ListIterator and Iterator in Java". In daily operation, I believe many people have doubts about the similarities and differences between ListIterator and Iterator in Java. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubts about "the similarities and differences between ListIterator and Iterator in Java". Next, please follow the editor to study!

1. What methods are included in the Iterator and ListIterator iterators?

The Iterator iterator contains the following methods:

HasNext (): returns true if the iterator points to an element after the location, otherwise returns false

Next (): returns the element in the collection where the Iterator points to the location

Remove (): deletes the element in the collection where the Iterator points to the location

The ListIterator iterator contains the following methods:

Add (E e): inserts the specified element into the list, before the current position of the iterator

HasNext (): when traversing the list in a forward direction, true is returned if there are elements after the list iterator, otherwise false is returned

HasPrevious (): if you iterate through the list in reverse and there are elements before the list iterator, return true, otherwise return false

Next (): returns the element in the list where the ListIterator points to the location

NextIndex (): returns the index of the elements following the desired position of ListIterator in the list

Previous (): returns the element in the list where ListIterator points to the front of the location

PreviousIndex (): returns the index of the elements preceding the desired position of the ListIterator in the list

Remove (): removes the last element returned by next () or previous () from the list (a bit of a mouthful, meaning that when using the hasNext () method on an iterator, delete the element after the ListIterator pointing to the position; when using the hasPrevious () method on the iterator, delete the element in front of the ListIterator pointing to the position)

Set (E e): changes the last element returned by next () or previous () from the list to the specified element e

2. What are the similarities between Iterator and ListIterator iterators?

Both iterators can be used when you need to traverse the elements in the collection without interfering with the traversal process.

3. What are the differences between Iterator and ListIterator iterators?

Depending on the scope of use, Iterator can be applied to all collections, Set, List, and Map, and subtypes of these collections. ListIterator can only be used with List and its subtypes.

LListIterator has an add method that can add objects to List, but Iterator cannot.

Both lListIterator and Iterator have hasNext () and next () methods that enable sequential backward traversal, but ListIterator has hasPrevious () and previous () methods that implement reverse (sequential forward) traversal. Iterator is not allowed.

LListIterator can locate the location of the current index, and nextIndex () and previousIndex () can do so. Iterator does not have this feature.

L can be deleted, but ListIterator can be used to modify objects, and the set () method can. Iterator can only be traversed and cannot be modified.

ArrayList stringArrayList1 = new ArrayList ()

ArrayList stringArrayList2 = new ArrayList ()

StringArrayList1.add ("ok")

StringArrayList1.add ("hello")

StringArrayList1.add ("world")

StringArrayList2.add ("OK")

StringArrayList2.add ("Hello")

StringArrayList2.add ("World")

StringArrayList1.addAll (stringArrayList2)

ListIterator iterator = stringArrayList1.listIterator ()

System.out.println ("output from the back:")

While (iterator.hasNext ()) {

System.out.println ("next=" + iterator.next ())

}

System.out.println ("\ r\ noutput from back to front:")

While (iterator.hasPrevious ()) {

System.out.println ("previous=" + iterator.previous ())

}

Note: be sure to output from front to back before you can output from back to front.

At this point, the study of "similarities and differences between ListIterator and Iterator in Java" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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