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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 13:18:17 EDT 2002 --><TITLE>: Class Hashtable</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/GraphMatrixVertex.html"><B>PREV CLASS</B></A> <A HREF="../structure/HashtableIterator.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="Hashtable.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 Hashtable</H2><PRE><A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">java.lang.Object</A> | +--<B>structure.Hashtable</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD><A HREF="../structure/Map.html">Map</A></DD></DL><HR><DL><DT>public class <B>Hashtable</B><DT>extends <A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A><DT>implements <A HREF="../structure/Map.html">Map</A></DL><P>Implements a dictionary as a table of hashed key-value pairs. Collisions are resolved through linear probing. Values used as keys in this structure must have a hashcode method that returns the same value when two keys are "equals". Initially, a table of suggested size is allocated. It will be expanded as the load factor (ratio of pairs to entries) grows. <P> Example Usage: <P> To create a hashtable by reading a collection of words and definitions from System.in we could use the following: <P> <pre> public static void main (String[] argv){ Hashtable dict = new <A HREF="../structure/Hashtable.html#Hashtable()"><CODE>Hashtable()</CODE></A>; ReadStream r = new ReadStream(); String word, def; System.out.println("Enter a word: "); while(!r.eof()){ word = r.readLine(); System.out.println("Enter a definition: "); def = r.readLine(); dict.<A HREF="../structure/Hashtable.html#put(java.lang.Object, java.lang.Object)"><CODE>put(word,def)</CODE></A>; System.out.println("Enter a word: "); } System.out.println(dict); } </pre><P><DL><DT><B>See Also: </B><DD><A HREF="../structure/ChainedHashtable.html"><CODE>ChainedHashtable</CODE></A></DL><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/Hashtable.html#capacity">capacity</A></B></CODE><BR> The size of the hashtable</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/Hashtable.html#count">count</A></B></CODE><BR> The number of key-value pairs in table.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected <A HREF="../structure/Association.html">Association</A>[]</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/Hashtable.html#data">data</A></B></CODE><BR> The data associated with the hashtable.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected double</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/Hashtable.html#loadFactor">loadFactor</A></B></CODE><BR> Load factor that causes rehashing of the table.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected static <A HREF="../structure/Association.html">Association</A></CODE></FONT></TD><TD><CODE><B><A HREF="../structure/Hashtable.html#reserved">reserved</A></B></CODE><BR> A single key-value pair to be used as a token indicating a reserved location in the hashtable.</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/Hashtable.html#Hashtable()">Hashtable</A></B>()</CODE><BR> Construct a hash table that is initially empty.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../structure/Hashtable.html#Hashtable(int)">Hashtable</A></B>(int initialCapacity)</CODE><BR> Construct a hash table that is capable of holding at least initialCapacity values.</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> void</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/Hashtable.html#clear()">clear</A></B>()</CODE><BR> Remove all key-value pairs from hashtable.</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/Hashtable.html#containsKey(java.lang.Object)">containsKey</A></B>(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A> key)</CODE><BR> Returns true iff a specific key appears within the table.</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/Hashtable.html#containsValue(java.lang.Object)">containsValue</A></B>(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A> value)</CODE><BR> Returns true if a specific value appears within the table.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../structure/Set.html">Set</A></CODE></FONT></TD><TD><CODE><B><A HREF="../structure/Hashtable.html#entrySet()">entrySet</A></B>()</CODE><BR> </TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../structure/Hashtable.html#extend()">extend</A></B>()</CODE><BR> </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/Hashtable.html#get(java.lang.Object)">get</A></B>(<A HREF="http://java.sun.com/j2se/1.3/docs/api/java/lang/Object.html">Object</A> key)</CODE><BR> Get the value associated with a key.</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/Hashtable.html#isEmpty()">isEmpty</A></B>()</CODE>⌨️ 快捷键说明
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