while loop, do-while, for each loop etc. They all are index based on traversing methods. But as we know Java is purely object oriented programming language in which we always have possible ways of doing things using objects. So Iterator is a way to traverse the data over the collection o...
TheIteratorinterface allows us to modify a collection while traversing it, which is more difficult with a simple for/while statement. This, in turn, gives us a good pattern we can use in many methods that only requires collections processing while maintaining good cohesion and low coupling. Fina...
This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible. 这时候可以采用java.util.concurrent包下面的线程安全的容器解决此异常。 最后要说的是,ConcurrentModificationException应该永远被用于解决一个bug,而不是检查程序的正确性(try...
false otherwise*/publicbooleanhasNext(){returnj<size;}// size is field of outer instance/*** Returns the next object in the iterator.** @return next object* @throws NoSuchElementException if there are no further elements*/publicEnext()throwsNoSuchElementException{if(j==size)throw...
In the example below, we have implemented thehasNext(),next(),remove()andforEachRemining()methods of theIteratorinterface in anArrayList. importjava.util.ArrayList;importjava.util.Iterator;classMain{publicstaticvoidmain(String[] args){// Creating an ArrayListArrayList<Integer> numbers =newArrayList<...
This interface is a member of the Java Collections Framework. API Note: An Enumeration can be converted into an Iterator by using the Enumeration.asIterator() method. Since: 1.2 See Also: Collection ListIterator Iterable Method Summary All MethodsInstance MethodsAbstract MethodsDefault Methods Modifier...
There are three important methods of thisIteratorinterface. //Returns true if the iteration has more elements.booleanhasNext();//Returns the next element in the iteration.Enext();//Removes from the underlying collection the last element returned by this iterator.defaultvoidremove(); ...
* Note that the {@link#remove} and {@link#set(Object)} methods are * not defined in terms of the cursor position; they are defined to * operate on the last element returned by a call to {@link#next} or * {@link#previous()}. * */public...
or* {@link ListIterator#add(Object) add} methods, the iterator willthrowa*{@link ConcurrentModificationException}. Thus, in the face of*concurrent modification, the iterator fails quickly and cleanly, rather* than risking arbitrary, non-deterministic behavior at an undetermined* time in the future...
IteratorextendsTraversable{/* Methods */abstractpublicmixedcurrent(void)abstractpublicscalarkey(void)abstractpublicvoidnext(void)abstractpublicvoidrewind(void)abstractpublicbooleanvalid(void)} 2、自定义迭代器类 现在我们了解了迭代器是什么,是时候我们可以自己构建一个迭代器了。