Explain the usage of iterator iterators in Java _java

Iterator (iterator)

An iterator is a design pattern that is an object that traverses and selects objects in a sequence, and developers do not need to understand the underlying structure of the sequence. Iterators are often referred to as "lightweight" objects because the cost of creating them is small.

The iterator function in Java is simpler and can only be moved in one Direction:

(1) using the method iterator () requires the container to return a iterator. The first time the iterator next () method is invoked, it returns the first element of the sequence. Note: The iterator () method is a java.lang.Iterable interface, inherited by collection.

(2) Use Next () to get the next element in the sequence.

(3) Use Hasnext () to check if there are any elements in the sequence.

(4) Remove the newly returned elements of the iterator using remove ().

Iterator is the simplest implementation of the Java iterator, with more functionality for the list design listiterator, which can traverse the list in two directions or insert and delete elements from the list.

Iterator Applications:

List L = new ArrayList ();
L.add ("AA");
L.add ("BB");
L.add ("cc");
for (Iterator iter = L.iterator (); Iter.hasnext ();) {
String str = (string) iter.next ();
System.out.println (str);
/* iterator for While loop
iterator iter = L.iterator ();
while (Iter.hasnext ()) {
String str = (String) iter.next ();
System.out.println (str);
*/

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