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lec07a - Iterators An iterator permits you to examine the...

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Iterators An iterator permits you to examine the elements of a data structure one at a time.
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Iterator Methods Iterator ix = x.iterator(); constructs and initializes an iterator to examine the elements of x ; constructed iterator is assigned to ix you must define the method iterator in the class for x
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Iterator Methods ix.hasNext() returns true iff x has a next element ix.next() throws NoSuchElementException if there is no next element returns next element otherwise
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Optional Iterator Method ix.remove() removes last element returned by ix.next() throws UnsupportedMethodException if method not implemented throws IllegalStateException if ix.next() not yet called or did not return an element
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Using An Iterator Iterator ix = x.iterator(); while (ix.hasNext()) examine(ix.next()); vs for ( int i = 0; i < x.size(); i++) examine(x.get(i));
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Merits Of An Iterator it is often possible to implement the method next so that its complexity is less than that of get many data structures do not have a get by index method iterators provide a uniform way to sequence through the elements of a data structure
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Java’s Array Linear List Class java.util.ArrayList Cadillac version of our ArrayLinearListWithIterator
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