docs/google-appengine-docs-20100817/appengine/docs/java/javadoc/com/google/appengine/api/datastore/Cursor.html

   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     <script type="text/javascript" language="JavaScript">
   6     ORIGINAL_PAGE_PATH = "/appengine/docs/java/javadoc/com/google/appengine/api/datastore/Cursor.html";
   7     </script>
   8
   9 <!-- Generated by javadoc (build 1.6.0-google-internal) on Fri Aug 13 13:39:09 CDT 2010 -->
  10 <TITLE>
  11 Cursor
  12 </TITLE>
  13
  14 <META NAME="date" CONTENT="2010-08-13">
  15
  16 <LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../../dev_javadoc.css" TITLE="Style">
  17
  18 <SCRIPT type="text/javascript">
  19 function windowTitle()
  20 {
  21     if (location.href.indexOf('is-external=true') == -1) {
  22         parent.document.title="Cursor";
  23     }
  24 }
  25 </SCRIPT>
  26 <NOSCRIPT>
  27 </NOSCRIPT>
  28
  29 </HEAD>
  30
  31 <BODY BGCOLOR="white" onload="windowTitle();">
  32 <HR>
  33
  34
  35 <!-- ========= START OF TOP NAVBAR ======= -->
  36 <A NAME="navbar_top"><!-- --></A>
  37 <A HREF="#skip-navbar_top" title="Skip navigation links"></A>
  38 <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY="">
  39 <TR>
  40 <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1">
  41 <A NAME="navbar_top_firstrow"><!-- --></A>
  42 <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY="">
  43   <TR ALIGN="center" VALIGN="top">
  44   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A>&nbsp;</TD>
  45   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A>&nbsp;</TD>
  46   <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> &nbsp;<FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT>&nbsp;</TD>
  47   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A>&nbsp;</TD>
  48   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A>&nbsp;</TD>
  49   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A>&nbsp;</TD>
  50   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A>&nbsp;</TD>
  51   </TR>
  52 </TABLE>
  53 </TD>
  54 <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM>
  55 </EM>
  56 </TD>
  57 </TR>
  58
  59 <TR>
  60 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
  61 &nbsp;<A HREF="CompositeIndexManager.html" title="class in com.google.appengine.api.datastore"><B>PREV CLASS</B></A>&nbsp;
  62 &nbsp;<A HREF="DatastoreApiHelper.html" title="class in com.google.appengine.api.datastore"><B>NEXT CLASS</B></A></FONT></TD>
  63 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
  64   <A HREF="../../../../../index.html?com/google/appengine/api/datastore/Cursor.html" target="_top"><B>FRAMES</B></A>  &nbsp;
  65 &nbsp;<A HREF="Cursor.html" target="_top"><B>NO FRAMES</B></A>  &nbsp;
  66 &nbsp;<SCRIPT type="text/javascript">
  67   <!--
  68   if(window==top) {
  69     document.writeln('<A HREF="../../../../../allclasses-noframe.html"><B>All Classes</B></A>');
  70   }
  71   //-->
  72 </SCRIPT>
  73 <NOSCRIPT>
  74   <A HREF="../../../../../allclasses-noframe.html"><B>All Classes</B></A>
  75 </NOSCRIPT>
  76
  77
  78 </FONT></TD>
  79 </TR>
  80 <TR>
  81 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
  82   SUMMARY:&nbsp;NESTED&nbsp;|&nbsp;FIELD&nbsp;|&nbsp;CONSTR&nbsp;|&nbsp;<A HREF="#method_summary">METHOD</A></FONT></TD>
  83 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
  84 DETAIL:&nbsp;FIELD&nbsp;|&nbsp;CONSTR&nbsp;|&nbsp;<A HREF="#method_detail">METHOD</A></FONT></TD>
  85 </TR>
  86 </TABLE>
  87 <A NAME="skip-navbar_top"></A>
  88 <!-- ========= END OF TOP NAVBAR ========= -->
  89
  90 <HR>
  91 <!-- ======== START OF CLASS DATA ======== -->
  92 <H2>
  93 <FONT SIZE="-1">
  94 com.google.appengine.api.datastore</FONT>
  95 <BR>
  96 Class Cursor</H2>
  97 <PRE>
  98 java.lang.Object
  99   <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by "><B>com.google.appengine.api.datastore.Cursor</B>
 100 </PRE>
 101 <DL>
 102 <DT><B>All Implemented Interfaces:</B> <DD>java.io.Serializable</DD>
 103 </DL>
 104 <HR>
 105 <DL>
 106 <DT><PRE>public final class <B>Cursor</B><DT>extends java.lang.Object<DT>implements java.io.Serializable</DL>
 107 </PRE>
 108
 109 <P>
 110 A cursor that represents a position in a query.
 111
 112  To resume a <A HREF="Query.html" title="class in com.google.appengine.api.datastore"><CODE>Query</CODE></A> at the position defined by a <A HREF="Cursor.html" title="class in com.google.appengine.api.datastore"><CODE>Cursor</CODE></A>, the
 113  <A HREF="Cursor.html" title="class in com.google.appengine.api.datastore"><CODE>Cursor</CODE></A> must be present in the <A HREF="FetchOptions.html" title="class in com.google.appengine.api.datastore"><CODE>FetchOptions</CODE></A> passed to a <A HREF="PreparedQuery.html" title="interface in com.google.appengine.api.datastore"><CODE>PreparedQuery</CODE></A> identical to the one it was created from.
 114  <p>
 115  Cursors can be retrieved from <code>PreparedQuery.asQueryResult*</code> functions.
 116  A typical use case would be:
 117
 118  <blockquote>
 119  <pre>
 120  Cursor originalCursor = preparedQuery.asQueryResultList(withLimit(20)).getCursor();
 121  String encodedCursor = original.toWebSafeString();
 122  </pre>
 123  </blockquote>
 124
 125  The encoded cursor can then be passed safely in a get or post arg of a web
 126  request and on another request the next batch of results can be retrieved with:
 127
 128  <blockquote>
 129  <pre>
 130  Cursor decodedCursor = Cursor.fromWebSafeString(encodedCursor);
 131  List<Entity> nextBatch = preparedQuery.asQueryResultList(withLimit(20).cursor(decoded));
 132  </pre>
 133  </blockquote>
 134 <P>
 135
 136 <P>
 137 <DL>
 138 <DT><B>See Also:</B><DD><A HREF="../../../../../serialized-form.html#com.google.appengine.api.datastore.Cursor">Serialized Form</A></DL>
 139 <HR>
 140
 141 <P>
 142
 143 <!-- ========== METHOD SUMMARY =========== -->
 144
 145 <A NAME="method_summary"><!-- --></A>
 146 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
 147 <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
 148 <TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
 149 <B>Method Summary</B></FONT></TH>
 150 </TR>
 151 <TR BGCOLOR="white" CLASS="TableRowColor">
 152 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
 153 <CODE>&nbsp;boolean</CODE></FONT></TD>
 154 <TD><CODE><B><A HREF="Cursor.html#equals(java.lang.Object)">equals</A></B>(java.lang.Object&nbsp;obj)</CODE>
 155
 156 <BR>
 157 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</TD>
 158 </TR>
 159 <TR BGCOLOR="white" CLASS="TableRowColor">
 160 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
 161 <CODE>static&nbsp;<A HREF="Cursor.html" title="class in com.google.appengine.api.datastore">Cursor</A></CODE></FONT></TD>
 162 <TD><CODE><B><A HREF="Cursor.html#fromWebSafeString(java.lang.String)">fromWebSafeString</A></B>(java.lang.String&nbsp;encodedCursor)</CODE>
 163
 164 <BR>
 165 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Decodes the given encoded cursor</TD>
 166 </TR>
 167 <TR BGCOLOR="white" CLASS="TableRowColor">
 168 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
 169 <CODE>&nbsp;int</CODE></FONT></TD>
 170 <TD><CODE><B><A HREF="Cursor.html#hashCode()">hashCode</A></B>()</CODE>
 171
 172 <BR>
 173 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</TD>
 174 </TR>
 175 <TR BGCOLOR="white" CLASS="TableRowColor">
 176 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
 177 <CODE>&nbsp;java.lang.String</CODE></FONT></TD>
 178 <TD><CODE><B><A HREF="Cursor.html#toString()">toString</A></B>()</CODE>
 179
 180 <BR>
 181 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</TD>
 182 </TR>
 183 <TR BGCOLOR="white" CLASS="TableRowColor">
 184 <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
 185 <CODE>&nbsp;java.lang.String</CODE></FONT></TD>
 186 <TD><CODE><B><A HREF="Cursor.html#toWebSafeString()">toWebSafeString</A></B>()</CODE>
 187
 188 <BR>
 189 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Encodes the current cursor as a web safe string that can later be decoded
 190  by <A HREF="Cursor.html#fromWebSafeString(java.lang.String)"><CODE>fromWebSafeString(String)</CODE></A></TD>
 191 </TR>
 192 </TABLE>
 193 &nbsp;<A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A>
 194 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
 195 <TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
 196 <TH ALIGN="left"><B>Methods inherited from class java.lang.Object</B></TH>
 197 </TR>
 198 <TR BGCOLOR="white" CLASS="TableRowColor">
 199 <TD><CODE>getClass, notify, notifyAll, wait, wait, wait</CODE></TD>
 200 </TR>
 201 </TABLE>
 202 &nbsp;
 203 <P>
 204
 205 <!-- ============ METHOD DETAIL ========== -->
 206
 207 <A NAME="method_detail"><!-- --></A>
 208 <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
 209 <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
 210 <TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2">
 211 <B>Method Detail</B></FONT></TH>
 212 </TR>
 213 </TABLE>
 214
 215 <A NAME="toWebSafeString()"><!-- --></A><H3>
 216 toWebSafeString</H3>
 217 <PRE>
 218 public java.lang.String <B>toWebSafeString</B>()</PRE>
 219 <DL>
 220 <DD>Encodes the current cursor as a web safe string that can later be decoded
 221  by <A HREF="Cursor.html#fromWebSafeString(java.lang.String)"><CODE>fromWebSafeString(String)</CODE></A>
 222 <P>
 223 <DD><DL>
 224 </DL>
 225 </DD>
 226 <DD><DL>
 227 </DL>
 228 </DD>
 229 </DL>
 230 <HR>
 231
 232 <A NAME="fromWebSafeString(java.lang.String)"><!-- --></A><H3>
 233 fromWebSafeString</H3>
 234 <PRE>
 235 public static <A HREF="Cursor.html" title="class in com.google.appengine.api.datastore">Cursor</A> <B>fromWebSafeString</B>(java.lang.String&nbsp;encodedCursor)</PRE>
 236 <DL>
 237 <DD>Decodes the given encoded cursor
 238 <P>
 239 <DD><DL>
 240 </DL>
 241 </DD>
 242 <DD><DL>
 243 <DT><B>Parameters:</B><DD><CODE>encodedCursor</CODE> -
 244 <DT><B>Returns:</B><DD>the decoded cursor
 245 <DT><B>Throws:</B>
 246 <DD><CODE>java.lang.IllegalArgumentException</CODE> - if the provided string is not a valid encoded cursor</DL>
 247 </DD>
 248 </DL>
 249 <HR>
 250
 251 <A NAME="equals(java.lang.Object)"><!-- --></A><H3>
 252 equals</H3>
 253 <PRE>
 254 public boolean <B>equals</B>(java.lang.Object&nbsp;obj)</PRE>
 255 <DL>
 256 <DD><DL>
 257 <DT><B>Overrides:</B><DD><CODE>equals</CODE> in class <CODE>java.lang.Object</CODE></DL>
 258 </DD>
 259 <DD><DL>
 260 </DL>
 261 </DD>
 262 </DL>
 263 <HR>
 264
 265 <A NAME="hashCode()"><!-- --></A><H3>
 266 hashCode</H3>
 267 <PRE>
 268 public int <B>hashCode</B>()</PRE>
 269 <DL>
 270 <DD><DL>
 271 <DT><B>Overrides:</B><DD><CODE>hashCode</CODE> in class <CODE>java.lang.Object</CODE></DL>
 272 </DD>
 273 <DD><DL>
 274 </DL>
 275 </DD>
 276 </DL>
 277 <HR>
 278
 279 <A NAME="toString()"><!-- --></A><H3>
 280 toString</H3>
 281 <PRE>
 282 public java.lang.String <B>toString</B>()</PRE>
 283 <DL>
 284 <DD><DL>
 285 <DT><B>Overrides:</B><DD><CODE>toString</CODE> in class <CODE>java.lang.Object</CODE></DL>
 286 </DD>
 287 <DD><DL>
 288 </DL>
 289 </DD>
 290 </DL>
 291 <!-- ========= END OF CLASS DATA ========= -->
 292 <HR>
 293
 294
 295 <!-- ======= START OF BOTTOM NAVBAR ====== -->
 296 <A NAME="navbar_bottom"><!-- --></A>
 297 <A HREF="#skip-navbar_bottom" title="Skip navigation links"></A>
 298 <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY="">
 299 <TR>
 300 <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1">
 301 <A NAME="navbar_bottom_firstrow"><!-- --></A>
 302 <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY="">
 303   <TR ALIGN="center" VALIGN="top">
 304   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A>&nbsp;</TD>
 305   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A>&nbsp;</TD>
 306   <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> &nbsp;<FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT>&nbsp;</TD>
 307   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A>&nbsp;</TD>
 308   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A>&nbsp;</TD>
 309   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A>&nbsp;</TD>
 310   <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A>&nbsp;</TD>
 311   </TR>
 312 </TABLE>
 313 </TD>
 314 <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM>
 315 </EM>
 316 </TD>
 317 </TR>
 318
 319 <TR>
 320 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
 321 &nbsp;<A HREF="CompositeIndexManager.html" title="class in com.google.appengine.api.datastore"><B>PREV CLASS</B></A>&nbsp;
 322 &nbsp;<A HREF="DatastoreApiHelper.html" title="class in com.google.appengine.api.datastore"><B>NEXT CLASS</B></A></FONT></TD>
 323 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
 324   <A HREF="../../../../../index.html?com/google/appengine/api/datastore/Cursor.html" target="_top"><B>FRAMES</B></A>  &nbsp;
 325 &nbsp;<A HREF="Cursor.html" target="_top"><B>NO FRAMES</B></A>  &nbsp;
 326 &nbsp;<SCRIPT type="text/javascript">
 327   <!--
 328   if(window==top) {
 329     document.writeln('<A HREF="../../../../../allclasses-noframe.html"><B>All Classes</B></A>');
 330   }
 331   //-->
 332 </SCRIPT>
 333 <NOSCRIPT>
 334   <A HREF="../../../../../allclasses-noframe.html"><B>All Classes</B></A>
 335 </NOSCRIPT>
 336
 337
 338 </FONT></TD>
 339 </TR>
 340 <TR>
 341 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
 342   SUMMARY:&nbsp;NESTED&nbsp;|&nbsp;FIELD&nbsp;|&nbsp;CONSTR&nbsp;|&nbsp;<A HREF="#method_summary">METHOD</A></FONT></TD>
 343 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
 344 DETAIL:&nbsp;FIELD&nbsp;|&nbsp;CONSTR&nbsp;|&nbsp;<A HREF="#method_detail">METHOD</A></FONT></TD>
 345 </TR>
 346 </TABLE>
 347 <A NAME="skip-navbar_bottom"></A>
 348 <!-- ======== END OF BOTTOM NAVBAR ======= -->
 349
 350 <HR>
 351
 352 </BODY>
 353 </HTML>