mapkey.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc (build 1.5.0_14) on Mon Jan 28 05:47:04 PST 2008 --><TITLE>MapKey (Java EE 5)</TITLE><META NAME="keywords" CONTENT="javax.persistence.MapKey class"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ parent.document.title="MapKey (Java EE 5)";}</SCRIPT><NOSCRIPT></NOSCRIPT></HEAD><BODY BGCOLOR="white" onload="windowTitle();"><!-- ========= START OF TOP NAVBAR ======= --><A NAME="navbar_top"><!-- --></A><A HREF="#skip-navbar_top" title="Skip navigation links"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <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="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></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../javax/persistence/ManyToOne.html" title="annotation in javax.persistence"><B>PREV CLASS</B></A> <A HREF="../../javax/persistence/MappedSuperclass.html" title="annotation in javax.persistence"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../index.html?javax/persistence/MapKey.html" target="_top"><B>FRAMES</B></A> <A HREF="MapKey.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--></SCRIPT><NOSCRIPT> <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: REQUIRED | <A HREF="#annotation_type_optional_element_summary">OPTIONAL</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: <A HREF="#annotation_type_element_detail">ELEMENT</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">javax.persistence</FONT><BR>Annotation Type MapKey</H2><HR><DL><DT><PRE><FONT SIZE="-1"><A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/Target.html" title="class or interface in java.lang.annotation">@Target</A>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/Target.html#value()" title="class or interface in java.lang.annotation">value</A>={<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/ElementType.html#METHOD" title="class or interface in java.lang.annotation">METHOD</A>,<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/ElementType.html#FIELD" title="class or interface in java.lang.annotation">FIELD</A>})<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/Retention.html" title="class or interface in java.lang.annotation">@Retention</A>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/Retention.html#value()" title="class or interface in java.lang.annotation">value</A>=<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/annotation/RetentionPolicy.html#RUNTIME" title="class or interface in java.lang.annotation">RUNTIME</A>)</FONT>public @interface <B>MapKey</B></DL></PRE><P>Is used to specify the map key for associations of type <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/util/Map.html" title="class or interface in java.util"><CODE>Map</CODE></A>. <p> If a persistent field or property other than the primary key is used as a map key then it is expected to have a uniqueness constraint associated with it. <pre> Example 1: @Entity public class Department { ... @OneToMany(mappedBy="department") @MapKey(name="empId") public Map<Integer, Employee> getEmployees() {... } ... } @Entity public class Employee { ... @Id Integer getEmpid() { ... } @ManyToOne @JoinColumn(name="dept_id") public Department getDepartment() { ... } ... } Example 2: @Entity public class Department { ... @OneToMany(mappedBy="department") @MapKey(name="empPK") public Map<EmployeePK, Employee> getEmployees() {... } ... } @Entity public class Employee { @EmbeddedId public EmployeePK getEmpPK() { ... } ... @ManyToOne @JoinColumn(name="dept_id") public Department getDepartment() { ... } ... } @Embeddable public class EmployeePK { String name; Date bday; } </pre><P><P><DL><DT><B>Since:</B></DT> <DD>Java Persistence 1.0</DD></DL><HR><P><!-- =========== ANNOTATION TYPE OPTIONAL MEMBER SUMMARY =========== --><A NAME="annotation_type_optional_element_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>Optional Element Summary</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/MapKey.html#name()">name</A></B></CODE><BR> The name of the persistent field or property of the associated entity that is used as the map key.</TD></TR></TABLE> <P><A NAME="name()"><!-- --></A><H3>name</H3><PRE>public abstract <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> <B>name</B></PRE><DL><DD>The name of the persistent field or property of the associated entity that is used as the map key. If the name element is not specified, the primary key of the associated entity is used as the map key. If the primary key is a composite primary key and is mapped as <A HREF="../../javax/persistence/IdClass.html" title="annotation in javax.persistence"><CODE>IdClass</CODE></A>, an instance of the primary key class is used as the key.<P><DD><DL></DL></DD><DD><DL></DL><DL><DT><B>Default:</B><DD>""</DD></DL></DL><!-- ========= END OF CLASS DATA ========= --><HR><!-- ======= START OF BOTTOM NAVBAR ====== --><A NAME="navbar_bottom"><!-- --></A><A HREF="#skip-navbar_bottom" title="Skip navigation links"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_bottom_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <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="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></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../javax/persistence/ManyToOne.html" title="annotation in javax.persistence"><B>PREV CLASS</B></A> <A HREF="../../javax/persistence/MappedSuperclass.html" title="annotation in javax.persistence"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../index.html?javax/persistence/MapKey.html" target="_top"><B>FRAMES</B></A> <A HREF="MapKey.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--></SCRIPT><NOSCRIPT> <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: REQUIRED | <A HREF="#annotation_type_optional_element_summary">OPTIONAL</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: <A HREF="#annotation_type_element_detail">ELEMENT</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_bottom"></A><!-- ======== END OF BOTTOM NAVBAR ======= --><HR><font size="-1"><a href="http://java.sun.com/webapps/bugreport">Submit a bug or feature</a> <p>Copyright 2007 Sun Microsystems, Inc. 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