The differences of Iterator and Iterable interface

淩亂°似流年 2022-02-09 12:39 230阅读 0赞

This post will describe som differences of Iterator and Iterable interface. Introduction with three aspects is given out.

*Firstly, relative abstract method.*

**Iterator interface:**

boolean hasNext(); // return true if there are elements to iterate.

E next(); //return the next element of iterator.

void remove(); //remove the last element of iterator.

**Iterable interface:**

Iterator<E> Iterator();//return an iterator with a group elements of data  type E.

*Secondly, when to use Iterable.*

1. If you want to reiterate the elements, you must use the Iterable interface.

2. If you want to use the loop foreach, you must use the Iterable interface. e.g., Iterable<E> its; for(E it:its) \{\}, ArrayList<T> als=new ArrayList<T>(); for(T al:als)\{\}

! foreach only uses the array or the instance of Iterable.

*Thirdly, all the classes implement the Iterable interface.*

AbstractCollection,  AbstractList, AbstractQueue,  AbstractSequentialList, AbstractSet,  ArrayBlockingQueue, ArrayDeque,  ArrayList, AttributeList,  BatchUpdateException, BeanContextServicesSupport, BeanContextSupport,  ConcurrentLinkedQueue, ConcurrentSkipListSet, CopyOnWriteArrayList,  CopyOnWriteArraySet, DataTruncation,  DelayQueue, EnumSet,  HashSet, JobStateReasons, LinkedBlockingDeque,  LinkedBlockingQueue, LinkedHashSet,  LinkedList, PriorityBlockingQueue, PriorityQueue,  RoleList, RoleUnresolvedList, RowSetWarning,  SerialException, ServiceLoader,  SQLClientInfoException, SQLDataException, SQLException,  SQLFeatureNotSupportedException, SQLIntegrityConstraintViolationException, SQLInvalidAuthorizationSpecException,  SQLNonTransientConnectionException, SQLNonTransientException, SQLRecoverableException,  SQLSyntaxErrorException, SQLTimeoutException, SQLTransactionRollbackException,  SQLTransientConnectionException, SQLTransientException, SQLWarning,  Stack, SyncFactoryException,  SynchronousQueue, SyncProviderException, TreeSet, Vector

*Fourthly, all the classes implement the Iterator interface.*

BeanContextSupport.BCSIterator, EventReaderDelegate,  Scanner