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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Frameset//EN""http://www.w3.org/TR/REC-html40/frameset.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc on Fri Aug 23 13:18:11 EDT 2002 --><TITLE>: Class ArrayIterator</TITLE><LINK REL ="stylesheet" TYPE="text/css" HREF="../stylesheet.css" TITLE="Style"></HEAD><BODY BGCOLOR="white"><!-- ========== START OF NAVBAR ========== --><A NAME="navbar_top"><!-- --></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0"><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3"> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM><a href=../copyright.html target=_top>© 1998-2002 McGraw-Hill</a></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../structure/AppendableList.html"><B>PREV CLASS</B></A> <A HREF="../structure/Assert.html"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../index.html" TARGET="_top"><B>FRAMES</B></A> <A HREF="ArrayIterator.html" TARGET="_top"><B>NO FRAMES</B></A></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: INNER | <A HREF="#field_summary">FIELD</A> | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: <A HREF="#field_detail">FIELD</A> | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><!-- =========== END OF NAVBAR =========== --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">structure</FONT><BR>Class ArrayIterator</H2><PRE><A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">java.lang.Object</A> | +--<A HREF="../structure/AbstractIterator.html">structure.AbstractIterator</A> | +--<B>structure.ArrayIterator</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD><A HREF="http://java.sun.com/j2se/1.3/docs/api/java/util/Enumeration.html">Enumeration</A>, <A HREF="http://java.sun.com/j2se/1.3/docs/api/java/util/Iterator.html">Iterator</A></DD></DL><HR><DL><DT>public class <B>ArrayIterator</B><DT>extends <A HREF="../structure/AbstractIterator.html">AbstractIterator</A></DL><P>A conveniece class that provies a mechanism to iterate over arrays that is analogous to the iteration techniques employed by the structures in this package. <P> Example Usage: <P> To prove that loops are faster than iteration we could use the following: <pre> public static void main(String[] argv){ //a randomly generated test string String testString = "For loops are much faster than iterators"; //an array over which to iterate String[] test = new String[10000000]; //longs to calculate lenght of computation long start, finish, iteration, looping; //populate test array with our test string for(int i=0; i<test.length; i++) test[i] = testString; //compute test for iteration start = System.currentTimeMillis(); for(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/util/Iterator.html"><CODE>Iterator</CODE></A> i = new <A HREF="../structure/ArrayIterator.html#ArrayIterator(java.lang.Object[])"><CODE>ArrayIterator(test)</CODE></A>; i.<A HREF="../structure/ArrayIterator.html#hasNext()"><CODE>hasNext()</CODE></A>;i.<A HREF="../structure/ArrayIterator.html#next()"><CODE>next()</CODE></A>){} finish = System.currentTimeMillis(); iteration = finish - start; System.out.println("Iteration over array took " + iteration + " milliseconds to perform."); //compute test for looping start = System.currentTimeMillis(); for(int i=0; i<test.length; i++){} finish = System.currentTimeMillis(); looping = finish - start; System.out.println("Looping over array took " + (finish-start) + " milliseconds to perform."); System.out.println("Iterators are " + (iteration/(double)looping) + " times " + "slower than loops."); } </pre><P><HR><P><!-- ======== INNER CLASS SUMMARY ======== --><!-- =========== FIELD SUMMARY =========== --><A NAME="field_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Field Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#count">count</A></B></CODE><BR> The number of elements in the array over which to iterate</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#current">current</A></B></CODE><BR> The current item in the iteration</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected <A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A>[]</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#data">data</A></B></CODE><BR> The array over which this iterator iterates</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#head">head</A></B></CODE><BR> The index of the first item in the iteration</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#remaining">remaining</A></B></CODE><BR> The number of items remaining in the itearation</TD></TR></TABLE> <!-- ======== CONSTRUCTOR SUMMARY ======== --><A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Constructor Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../structure/ArrayIterator.html#ArrayIterator(java.lang.Object[])">ArrayIterator</A></B>(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A>[] source)</CODE><BR> Construct an iterator that iterates over the entire contents of an array.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../structure/ArrayIterator.html#ArrayIterator(java.lang.Object[], int, int)">ArrayIterator</A></B>(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A>[] source, int first, int size)</CODE><BR> Constructs an iterator that will iterate over a specified portion of the source array.</TD></TR></TABLE> <!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Method Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#get()">get</A></B>()</CODE><BR> Return the object currently specified by the iteration without advancing the iterator to the next object.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#hasNext()">hasNext</A></B>()</CODE><BR> Returns true iff there are elements specified by our iterator that have not been visited by the current iteration.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static void</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#main(java.lang.String[])">main</A></B>(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/String.html">String</A>[] argv)</CODE><BR> test code to prove that iterators are slower than for loops</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../structure/ArrayIterator.html#next()">next</A></B>()</CODE><BR> Return the next object in our iteration and advance the iterator to the next object in the iteration.</TD></TR>⌨️ 快捷键说明
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