valueexpression.html

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<A NAME="ValueExpression()"><!-- --></A><H3>
ValueExpression</H3>
<PRE>
public <B>ValueExpression</B>()</PRE>
<DL>
</DL>

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<A NAME="getValue(javax.el.ELContext)"><!-- --></A><H3>
getValue</H3>
<PRE>
public abstract <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> <B>getValue</B>(<A HREF="../../javax/el/ELContext.html" title="class in javax.el">ELContext</A>&nbsp;context)</PRE>
<DL>
<DD>Evaluates the expression relative to the provided context, and 
 returns the resulting value.

 <p>The resulting value is automatically coerced to the type
 returned by <code>getExpectedType()</code>, which was
 provided to the <code>ExpressionFactory</code> when this
 expression was created.</p>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>context</CODE> - The context of this evaluation.
<DT><B>Returns:</B><DD>The result of the expression evaluation.
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if context is <code>null</code>.
<DD><CODE><A HREF="../../javax/el/PropertyNotFoundException.html" title="class in javax.el">PropertyNotFoundException</A></CODE> - if one of the property
     resolutions failed because a specified variable or property 
     does not exist or is not readable.
<DD><CODE><A HREF="../../javax/el/ELException.html" title="class in javax.el">ELException</A></CODE> - if an exception was thrown while performing
     property or variable resolution. The thrown exception
     must be included as the cause property of this exception, if
     available.</DL>
</DD>
</DL>
<HR>

<A NAME="setValue(javax.el.ELContext, java.lang.Object)"><!-- --></A><H3>
setValue</H3>
<PRE>
public abstract void <B>setValue</B>(<A HREF="../../javax/el/ELContext.html" title="class in javax.el">ELContext</A>&nbsp;context,
                              <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A>&nbsp;value)</PRE>
<DL>
<DD>Evaluates the expression relative to the provided context, and 
 sets the result to the provided value.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>context</CODE> - The context of this evaluation.<DD><CODE>value</CODE> - The new value to be set.
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if context is <code>null</code>.
<DD><CODE><A HREF="../../javax/el/PropertyNotFoundException.html" title="class in javax.el">PropertyNotFoundException</A></CODE> - if one of the property
     resolutions failed because a specified variable or property 
     does not exist or is not readable.
<DD><CODE><A HREF="../../javax/el/PropertyNotWritableException.html" title="class in javax.el">PropertyNotWritableException</A></CODE> - if the final variable or
     property resolution failed because the specified
     variable or property is not writable.
<DD><CODE><A HREF="../../javax/el/ELException.html" title="class in javax.el">ELException</A></CODE> - if an exception was thrown while attempting to
     set the property or variable. The thrown exception
     must be included as the cause property of this exception, if
     available.</DL>
</DD>
</DL>
<HR>

<A NAME="isReadOnly(javax.el.ELContext)"><!-- --></A><H3>
isReadOnly</H3>
<PRE>
public abstract boolean <B>isReadOnly</B>(<A HREF="../../javax/el/ELContext.html" title="class in javax.el">ELContext</A>&nbsp;context)</PRE>
<DL>
<DD>Evaluates the expression relative to the provided context, and 
 returns <code>true</code> if a call to <A HREF="../../javax/el/ValueExpression.html#setValue(javax.el.ELContext, java.lang.Object)"><CODE>setValue(javax.el.ELContext, java.lang.Object)</CODE></A> will 
 always fail.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>context</CODE> - The context of this evaluation.
<DT><B>Returns:</B><DD><code>true</code> if the expression is read-only or
     <code>false</code> if not.
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if context is <code>null</code>.
<DD><CODE><A HREF="../../javax/el/PropertyNotFoundException.html" title="class in javax.el">PropertyNotFoundException</A></CODE> - if one of the property
     resolutions failed because a specified variable or property 
     does not exist or is not readable.
<DD><CODE><A HREF="../../javax/el/ELException.html" title="class in javax.el">ELException</A></CODE> - if an exception was thrown while performing
     property or variable resolution. The thrown exception
     must be included as the cause property of this exception, if
     available.
     * @throws NullPointerException if context is <code>null</code></DL>
</DD>
</DL>
<HR>

<A NAME="getType(javax.el.ELContext)"><!-- --></A><H3>
getType</H3>
<PRE>
public abstract <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Class.html" title="class or interface in java.lang">Class</A>&lt;?&gt; <B>getType</B>(<A HREF="../../javax/el/ELContext.html" title="class in javax.el">ELContext</A>&nbsp;context)</PRE>
<DL>
<DD>Evaluates the expression relative to the provided context, and 
 returns the most general type that is acceptable for an object to be 
 passed as the <code>value</code> parameter in a future call 
 to the <A HREF="../../javax/el/ValueExpression.html#setValue(javax.el.ELContext, java.lang.Object)"><CODE>setValue(javax.el.ELContext, java.lang.Object)</CODE></A> method.

 <p>This is not always the same as <code>getValue().getClass()</code>.
 For example, in the case of an expression that references an 
 array element, the <code>getType</code> method will return the 
 element type of the array, which might be a superclass of the type 
 of the actual element that is currently in the specified 
 array element.</p>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>context</CODE> - The context of this evaluation.
<DT><B>Returns:</B><DD>the most general acceptable type; otherwise undefined.
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if context is <code>null</code>.
<DD><CODE><A HREF="../../javax/el/PropertyNotFoundException.html" title="class in javax.el">PropertyNotFoundException</A></CODE> - if one of the property
     resolutions failed because a specified variable or property 
     does not exist or is not readable.
<DD><CODE><A HREF="../../javax/el/ELException.html" title="class in javax.el">ELException</A></CODE> - if an exception was thrown while performing
     property or variable resolution. The thrown exception
     must be included as the cause property of this exception, if
     available.</DL>
</DD>
</DL>
<HR>

<A NAME="getExpectedType()"><!-- --></A><H3>
getExpectedType</H3>
<PRE>
public abstract <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Class.html" title="class or interface in java.lang">Class</A>&lt;?&gt; <B>getExpectedType</B>()</PRE>
<DL>
<DD>Returns the type the result of the expression will be coerced to 
 after evaluation.
<P>
<DD><DL>

<DT><B>Returns:</B><DD>the <code>expectedType</code> passed to the
     <code>ExpressionFactory.createValueExpression</code> method
     that created this <code>ValueExpression</code>.</DL>
</DD>
</DL>
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