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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 Thu Apr 27 23:36:46 PDT 2000 --><TITLE>Java 2 Platform SE v1.3: Class AbstractMap</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="../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <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="class-use/AbstractMap.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </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-files/index-1.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><b>Java<sup><font size=-2>TM</font></sup> 2 Platform<br>Std. Ed. v1.3</b></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../java/util/AbstractList.html"><B>PREV CLASS</B></A> <A HREF="../../java/util/AbstractSequentialList.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="AbstractMap.html" TARGET="_top"><B>NO FRAMES</B></A></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: INNER | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <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">java.util</FONT><BR>Class AbstractMap</H2><PRE><A HREF="../../java/lang/Object.html">java.lang.Object</A> | +--<B>java.util.AbstractMap</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD><A HREF="../../java/util/Map.html">Map</A></DD></DL><DL><DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../java/util/HashMap.html">HashMap</A>, <A HREF="../../java/util/TreeMap.html">TreeMap</A>, <A HREF="../../java/util/WeakHashMap.html">WeakHashMap</A></DD></DL><HR><DL><DT>public abstract class <B>AbstractMap</B><DT>extends <A HREF="../../java/lang/Object.html">Object</A><DT>implements <A HREF="../../java/util/Map.html">Map</A></DL><P>This class provides a skeletal implementation of the <tt>Map</tt> interface, to minimize the effort required to implement this interface. <p> To implement an unmodifiable map, the programmer needs only to extend this class and provide an implementation for the <tt>entrySet</tt> method, which returns a set-view of the map's mappings. Typically, the returned set will, in turn, be implemented atop <tt>AbstractSet</tt>. This set should not support the <tt>add</tt> or <tt>remove</tt> methods, and its iterator should not support the <tt>remove</tt> method.<p> To implement a modifiable map, the programmer must additionally override this class's <tt>put</tt> method (which otherwise throws an <tt>UnsupportedOperationException</tt>), and the iterator returned by <tt>entrySet().iterator()</tt> must additionally implement its <tt>remove</tt> method.<p> The programmer should generally provide a void (no argument) and map constructor, as per the recommendation in the <tt>Map</tt> interface specification.<p> The documentation for each non-abstract methods in this class describes its implementation in detail. Each of these methods may be overridden if the map being implemented admits a more efficient implementation.<P><DL><DT><B>Since: </B><DD>1.2</DD><DT><B>See Also: </B><DD><A HREF="../../java/util/Map.html"><CODE>Map</CODE></A>, <A HREF="../../java/util/Collection.html"><CODE>Collection</CODE></A></DL><HR><P><!-- ======== INNER CLASS SUMMARY ======== --><A NAME="inner_classes_inherited_from_class_java.util.Map"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"><TD><B>Inner classes inherited from class java.util.<A HREF="../../java/util/Map.html">Map</A></B></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><A HREF="../../java/util/Map.Entry.html">Map.Entry</A></CODE></TD></TR></TABLE> <!-- =========== FIELD SUMMARY =========== --><!-- ======== 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 ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected </CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#AbstractMap()">AbstractMap</A></B>()</CODE><BR> Sole constructor.</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="../../java/util/AbstractMap.html#clear()">clear</A></B>()</CODE><BR> Removes all mappings from this map (optional operation).</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="../../java/util/AbstractMap.html#containsKey(java.lang.Object)">containsKey</A></B>(<A HREF="../../java/lang/Object.html">Object</A> key)</CODE><BR> Returns <tt>true</tt> if this map contains a mapping for the specified 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="../../java/util/AbstractMap.html#containsValue(java.lang.Object)">containsValue</A></B>(<A HREF="../../java/lang/Object.html">Object</A> value)</CODE><BR> Returns <tt>true</tt> if this map maps one or more keys to this value.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>abstract <A HREF="../../java/util/Set.html">Set</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#entrySet()">entrySet</A></B>()</CODE><BR> Returns a set view of the mappings contained in this map.</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="../../java/util/AbstractMap.html#equals(java.lang.Object)">equals</A></B>(<A HREF="../../java/lang/Object.html">Object</A> o)</CODE><BR> Compares the specified object with this map for equality.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../java/lang/Object.html">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#get(java.lang.Object)">get</A></B>(<A HREF="../../java/lang/Object.html">Object</A> key)</CODE><BR> Returns the value to which this map maps the specified key.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#hashCode()">hashCode</A></B>()</CODE><BR> Returns the hash code value for this map.</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="../../java/util/AbstractMap.html#isEmpty()">isEmpty</A></B>()</CODE><BR> Returns <tt>true</tt> if this map contains no key-value mappings.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../java/util/Set.html">Set</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#keySet()">keySet</A></B>()</CODE><BR> Returns a Set view of the keys contained in this map.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../java/lang/Object.html">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#put(java.lang.Object, java.lang.Object)">put</A></B>(<A HREF="../../java/lang/Object.html">Object</A> key, <A HREF="../../java/lang/Object.html">Object</A> value)</CODE><BR> Associates the specified value with the specified key in this map (optional operation).</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="../../java/util/AbstractMap.html#putAll(java.util.Map)">putAll</A></B>(<A HREF="../../java/util/Map.html">Map</A> t)</CODE><BR> Copies all of the mappings from the specified map to this map (optional operation).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../java/lang/Object.html">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/AbstractMap.html#remove(java.lang.Object)">remove</A></B>(<A HREF="../../java/lang/Object.html">Object</A> key)</CODE><BR> Removes the mapping for this key from this map if present (optional operation).</TD></TR>⌨️ 快捷键说明
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