1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2 <!--NewPage--> 3 <HTML> 4 <HEAD> 5 <!-- Generated by javadoc (build 1.6.0-google-internal) on Mon Jan 04 20:47:58 PST 2010 --> 6 <TITLE> 7 ForwardingObject (Guava Libraries 2010.01.04) 8 </TITLE> 9 10 <META NAME="date" CONTENT="2010-01-04"> 11 12 <LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../stylesheet.css" TITLE="Style"> 13 14 <SCRIPT type="text/javascript"> 15 function windowTitle() 16 { 17 if (location.href.indexOf('is-external=true') == -1) { 18 parent.document.title="ForwardingObject (Guava Libraries 2010.01.04)"; 19 } 20 } 21 </SCRIPT> 22 <NOSCRIPT> 23 </NOSCRIPT> 24 25 </HEAD> 26 27 <BODY BGCOLOR="white" onload="windowTitle();"> 28 <HR> 29 30 31 <!-- ========= START OF TOP NAVBAR ======= --> 32 <A NAME="navbar_top"><!-- --></A> 33 <A HREF="#skip-navbar_top" title="Skip navigation links"></A> 34 <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> 35 <TR> 36 <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> 37 <A NAME="navbar_top_firstrow"><!-- --></A> 38 <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> 39 <TR ALIGN="center" VALIGN="top"> 40 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> 41 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> 42 <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> 43 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/ForwardingObject.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> 44 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> 45 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> 46 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> 47 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> 48 </TR> 49 </TABLE> 50 </TD> 51 <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> 52 </EM> 53 </TD> 54 </TR> 55 56 <TR> 57 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 58 <A HREF="../../../../com/google/common/collect/ForwardingMultiset.html" title="class in com.google.common.collect"><B>PREV CLASS</B></A> 59 <A HREF="../../../../com/google/common/collect/ForwardingQueue.html" title="class in com.google.common.collect"><B>NEXT CLASS</B></A></FONT></TD> 60 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 61 <A HREF="../../../../index.html?com/google/common/collect/ForwardingObject.html" target="_top"><B>FRAMES</B></A> 62 <A HREF="ForwardingObject.html" target="_top"><B>NO FRAMES</B></A> 63 <SCRIPT type="text/javascript"> 64 <!-- 65 if(window==top) { 66 document.writeln('<A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A>'); 67 } 68 //--> 69 </SCRIPT> 70 <NOSCRIPT> 71 <A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A> 72 </NOSCRIPT> 73 74 75 </FONT></TD> 76 </TR> 77 <TR> 78 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 79 SUMMARY: NESTED | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD> 80 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 81 DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD> 82 </TR> 83 </TABLE> 84 <A NAME="skip-navbar_top"></A> 85 <!-- ========= END OF TOP NAVBAR ========= --> 86 87 <HR> 88 <!-- ======== START OF CLASS DATA ======== --> 89 <H2> 90 <FONT SIZE="-1"> 91 com.google.common.collect</FONT> 92 <BR> 93 Class ForwardingObject</H2> 94 <PRE> 95 <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">java.lang.Object</A> 96 <IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><B>com.google.common.collect.ForwardingObject</B> 97 </PRE> 98 <DL> 99 <DT><B>Direct Known Subclasses:</B> <DD><A HREF="../../../../com/google/common/collect/ForwardingCollection.html" title="class in com.google.common.collect">ForwardingCollection</A>, <A HREF="../../../../com/google/common/util/concurrent/ForwardingFuture.html" title="class in com.google.common.util.concurrent">ForwardingFuture</A>, <A HREF="../../../../com/google/common/collect/ForwardingIterator.html" title="class in com.google.common.collect">ForwardingIterator</A>, <A HREF="../../../../com/google/common/collect/ForwardingMap.html" title="class in com.google.common.collect">ForwardingMap</A>, <A HREF="../../../../com/google/common/collect/ForwardingMapEntry.html" title="class in com.google.common.collect">ForwardingMapEntry</A>, <A HREF="../../../../com/google/common/collect/ForwardingMultimap.html" title="class in com.google.common.collect">ForwardingMultimap</A>, <A HREF="../../../../com/google/common/util/concurrent/ForwardingService.html" title="class in com.google.common.util.concurrent">ForwardingService</A></DD> 100 </DL> 101 <HR> 102 <DL> 103 <DT><PRE>public abstract class <B>ForwardingObject</B><DT>extends <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></DL> 104 </PRE> 105 106 <P> 107 An abstract base class for implementing the <a 108 href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 109 The <A HREF="../../../../com/google/common/collect/ForwardingObject.html#delegate()"><CODE>delegate()</CODE></A> method must be overridden to return the instance 110 being decorated. 111 112 This class does <i>not</i> forward the <code>hashCode</code> and <code>equals</code> 113 methods through to the backing object, but relies on <code>Object</code>'s 114 implementation. This is necessary to preserve the symmetry of <code>equals</code>. 115 Custom definitions of equality are usually based on an interface, such as 116 <code>Set</code> or <code>List</code>, so that the implementation of <code>equals</code> can 117 cast the object being tested for equality to the custom interface. <code>ForwardingObject</code> implements no such custom interfaces directly; they 118 are implemented only in subclasses. Therefore, forwarding <code>equals</code> 119 would break symmetry, as the forwarding object might consider itself equal to 120 the object being tested, but the reverse could not be true. This behavior is 121 consistent with the JDK's collection wrappers, such as 122 <A HREF="http://java.sun.com/javase/6/docs/api/java/util/Collections.html?is-external=true#unmodifiableCollection(java.util.Collection)" title="class or interface in java.util"><CODE>Collections.unmodifiableCollection(java.util.Collection<? extends T>)</CODE></A>. Use an 123 interface-specific subclass of <code>ForwardingObject</code>, such as <A HREF="../../../../com/google/common/collect/ForwardingList.html" title="class in com.google.common.collect"><CODE>ForwardingList</CODE></A>, to preserve equality behavior, or override <code>equals</code> 124 directly. 125 126 <p>The <code>toString</code> method is forwarded to the delegate. Although this 127 class does not implement <A HREF="http://java.sun.com/javase/6/docs/api/java/io/Serializable.html?is-external=true" title="class or interface in java.io"><CODE>Serializable</CODE></A>, a serializable subclass may be 128 created since this class has a parameter-less constructor. 129 <P> 130 131 <P> 132 <DL> 133 <DT><B>Since:</B></DT> 134 <DD>2010.01.04 <b>stable</b> (imported from Google Collections Library)</DD> 135 <DT><B>Author:</B></DT> 136 <DD>Mike Bostock</DD> 137 </DL> 138 <HR> 139 140 <P> 141 142 <!-- ======== CONSTRUCTOR SUMMARY ======== --> 143 144 <A NAME="constructor_summary"><!-- --></A> 145 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 146 <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> 147 <TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"> 148 <B>Constructor Summary</B></FONT></TH> 149 </TR> 150 <TR BGCOLOR="white" CLASS="TableRowColor"> 151 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> 152 <CODE>protected </CODE></FONT></TD> 153 <TD><CODE><B><A HREF="../../../../com/google/common/collect/ForwardingObject.html#ForwardingObject()">ForwardingObject</A></B>()</CODE> 154 155 <BR> 156 Sole constructor.</TD> 157 </TR> 158 </TABLE> 159 160 <!-- ========== METHOD SUMMARY =========== --> 161 162 <A NAME="method_summary"><!-- --></A> 163 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 164 <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> 165 <TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"> 166 <B>Method Summary</B></FONT></TH> 167 </TR> 168 <TR BGCOLOR="white" CLASS="TableRowColor"> 169 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> 170 <CODE>protected abstract <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></CODE></FONT></TD> 171 <TD><CODE><B><A HREF="../../../../com/google/common/collect/ForwardingObject.html#delegate()">delegate</A></B>()</CODE> 172 173 <BR> 174 Returns the backing delegate instance that methods are forwarded to.</TD> 175 </TR> 176 <TR BGCOLOR="white" CLASS="TableRowColor"> 177 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> 178 <CODE> <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/String.html?is-external=true" title="class or interface in java.lang">String</A></CODE></FONT></TD> 179 <TD><CODE><B><A HREF="../../../../com/google/common/collect/ForwardingObject.html#toString()">toString</A></B>()</CODE> 180 181 <BR> 182 Returns the string representation generated by the delegate's 183 <code>toString</code> method.</TD> 184 </TR> 185 </TABLE> 186 <A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A> 187 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 188 <TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"> 189 <TH ALIGN="left"><B>Methods inherited from class java.lang.<A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></B></TH> 190 </TR> 191 <TR BGCOLOR="white" CLASS="TableRowColor"> 192 <TD><CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#clone()" title="class or interface in java.lang">clone</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#equals(java.lang.Object)" title="class or interface in java.lang">equals</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#finalize()" title="class or interface in java.lang">finalize</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#getClass()" title="class or interface in java.lang">getClass</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#hashCode()" title="class or interface in java.lang">hashCode</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notify()" title="class or interface in java.lang">notify</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notifyAll()" title="class or interface in java.lang">notifyAll</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait()" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long)" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long, int)" title="class or interface in java.lang">wait</A></CODE></TD> 193 </TR> 194 </TABLE> 195 196 <P> 197 198 <!-- ========= CONSTRUCTOR DETAIL ======== --> 199 200 <A NAME="constructor_detail"><!-- --></A> 201 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 202 <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> 203 <TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2"> 204 <B>Constructor Detail</B></FONT></TH> 205 </TR> 206 </TABLE> 207 208 <A NAME="ForwardingObject()"><!-- --></A><H3> 209 ForwardingObject</H3> 210 <PRE> 211 protected <B>ForwardingObject</B>()</PRE> 212 <DL> 213 <DD>Sole constructor. 214 <P> 215 </DL> 216 217 <!-- ============ METHOD DETAIL ========== --> 218 219 <A NAME="method_detail"><!-- --></A> 220 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 221 <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> 222 <TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2"> 223 <B>Method Detail</B></FONT></TH> 224 </TR> 225 </TABLE> 226 227 <A NAME="delegate()"><!-- --></A><H3> 228 delegate</H3> 229 <PRE> 230 protected abstract <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A> <B>delegate</B>()</PRE> 231 <DL> 232 <DD>Returns the backing delegate instance that methods are forwarded to. 233 Abstract subclasses generally override this method with an abstract method 234 that has a more specific return type, such as <A HREF="../../../../com/google/common/collect/ForwardingSet.html#delegate()"><CODE>ForwardingSet.delegate()</CODE></A>. Concrete subclasses override this method to supply 235 the instance being decorated. 236 <P> 237 <DD><DL> 238 </DL> 239 </DD> 240 </DL> 241 <HR> 242 243 <A NAME="toString()"><!-- --></A><H3> 244 toString</H3> 245 <PRE> 246 public <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/String.html?is-external=true" title="class or interface in java.lang">String</A> <B>toString</B>()</PRE> 247 <DL> 248 <DD>Returns the string representation generated by the delegate's 249 <code>toString</code> method. 250 <P> 251 <DD><DL> 252 <DT><B>Overrides:</B><DD><CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#toString()" title="class or interface in java.lang">toString</A></CODE> in class <CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></CODE></DL> 253 </DD> 254 <DD><DL> 255 </DL> 256 </DD> 257 </DL> 258 <!-- ========= END OF CLASS DATA ========= --> 259 <HR> 260 261 262 <!-- ======= START OF BOTTOM NAVBAR ====== --> 263 <A NAME="navbar_bottom"><!-- --></A> 264 <A HREF="#skip-navbar_bottom" title="Skip navigation links"></A> 265 <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> 266 <TR> 267 <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> 268 <A NAME="navbar_bottom_firstrow"><!-- --></A> 269 <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> 270 <TR ALIGN="center" VALIGN="top"> 271 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> 272 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> 273 <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> 274 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/ForwardingObject.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> 275 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> 276 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> 277 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> 278 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> 279 </TR> 280 </TABLE> 281 </TD> 282 <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> 283 </EM> 284 </TD> 285 </TR> 286 287 <TR> 288 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 289 <A HREF="../../../../com/google/common/collect/ForwardingMultiset.html" title="class in com.google.common.collect"><B>PREV CLASS</B></A> 290 <A HREF="../../../../com/google/common/collect/ForwardingQueue.html" title="class in com.google.common.collect"><B>NEXT CLASS</B></A></FONT></TD> 291 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 292 <A HREF="../../../../index.html?com/google/common/collect/ForwardingObject.html" target="_top"><B>FRAMES</B></A> 293 <A HREF="ForwardingObject.html" target="_top"><B>NO FRAMES</B></A> 294 <SCRIPT type="text/javascript"> 295 <!-- 296 if(window==top) { 297 document.writeln('<A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A>'); 298 } 299 //--> 300 </SCRIPT> 301 <NOSCRIPT> 302 <A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A> 303 </NOSCRIPT> 304 305 306 </FONT></TD> 307 </TR> 308 <TR> 309 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 310 SUMMARY: NESTED | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD> 311 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 312 DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD> 313 </TR> 314 </TABLE> 315 <A NAME="skip-navbar_bottom"></A> 316 <!-- ======== END OF BOTTOM NAVBAR ======= --> 317 318 <HR> 319 320 </BODY> 321 </HTML> 322
