Class ArrayELResolver
- java.lang.Object
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- javax.el.ELResolver
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- javax.el.ArrayELResolver
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public class ArrayELResolver extends ELResolver
Defines property resolution behavior on arrays.This resolver handles base objects that are Java language arrays. It accepts any object as a property and coerces that object into an integer index into the array. The resulting value is the value in the array at that index.
This resolver can be constructed in read-only mode, which means that
isReadOnly
will always returntrue
andsetValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object)
will always throwPropertyNotWritableException
.ELResolver
s are combined together usingCompositeELResolver
s, to define rich semantics for evaluating an expression. See the javadocs forELResolver
for details.- Since:
- JSP 2.1
- See Also:
CompositeELResolver
,ELResolver
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Field Summary
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Fields inherited from class javax.el.ELResolver
RESOLVABLE_AT_DESIGN_TIME, TYPE
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Constructor Summary
Constructors Constructor Description ArrayELResolver()
Creates a new read/writeArrayELResolver
.ArrayELResolver(boolean isReadOnly)
Creates a newArrayELResolver
whose read-only status is determined by the given parameter.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Class<?>
getCommonPropertyType(ELContext context, java.lang.Object base)
If the base object is a Java language array, returns the most general type that this resolver accepts for theproperty
argument.java.util.Iterator<java.beans.FeatureDescriptor>
getFeatureDescriptors(ELContext context, java.lang.Object base)
Always returnsnull
, since there is no reason to iterate through set set of all integers.java.lang.Class<?>
getType(ELContext context, java.lang.Object base, java.lang.Object property)
If the base object is an array, returns the most general acceptable type for a value in this array.java.lang.Object
getValue(ELContext context, java.lang.Object base, java.lang.Object property)
If the base object is a Java language array, returns the value at the given index.boolean
isReadOnly(ELContext context, java.lang.Object base, java.lang.Object property)
If the base object is a Java language array, returns whether a call tosetValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object)
will always fail.void
setValue(ELContext context, java.lang.Object base, java.lang.Object property, java.lang.Object val)
If the base object is a Java language array, attempts to set the value at the given index with the given value.-
Methods inherited from class javax.el.ELResolver
convertToType, invoke
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Constructor Detail
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ArrayELResolver
public ArrayELResolver()
Creates a new read/writeArrayELResolver
.
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ArrayELResolver
public ArrayELResolver(boolean isReadOnly)
Creates a newArrayELResolver
whose read-only status is determined by the given parameter.- Parameters:
isReadOnly
-true
if this resolver cannot modify arrays;false
otherwise.
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Method Detail
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getType
public java.lang.Class<?> getType(ELContext context, java.lang.Object base, java.lang.Object property)
If the base object is an array, returns the most general acceptable type for a value in this array.If the base is a
array
, thepropertyResolved
property of theELContext
object must be set totrue
by this resolver, before returning. If this property is nottrue
after this method is called, the caller should ignore the return value.Assuming the base is an
array
, this method will always returnbase.getClass().getComponentType()
, which is the most general type of component that can be stored at any given index in the array.- Specified by:
getType
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- The array to analyze. Only bases that are Java language arrays are handled by this resolver.property
- The index of the element in the array to return the acceptable type for. Will be coerced into an integer, but otherwise ignored by this resolver.- Returns:
- If the
propertyResolved
property ofELContext
was set totrue
, then the most general acceptable type; otherwise undefined. - Throws:
PropertyNotFoundException
- if the given index is out of bounds for this array.java.lang.NullPointerException
- if context isnull
ELException
- if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
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getValue
public java.lang.Object getValue(ELContext context, java.lang.Object base, java.lang.Object property)
If the base object is a Java language array, returns the value at the given index. The index is specified by theproperty
argument, and coerced into an integer. If the coercion could not be performed, anIllegalArgumentException
is thrown. If the index is out of bounds,null
is returned.If the base is a Java language array, the
propertyResolved
property of theELContext
object must be set totrue
by this resolver, before returning. If this property is nottrue
after this method is called, the caller should ignore the return value.- Specified by:
getValue
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- The array to analyze. Only bases that are Java language arrays are handled by this resolver.property
- The index of the value to be returned. Will be coerced into an integer.- Returns:
- If the
propertyResolved
property ofELContext
was set totrue
, then the value at the given index ornull
if the index was out of bounds. Otherwise, undefined. - Throws:
java.lang.IllegalArgumentException
- if the property could not be coerced into an integer.java.lang.NullPointerException
- if context isnull
.ELException
- if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
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setValue
public void setValue(ELContext context, java.lang.Object base, java.lang.Object property, java.lang.Object val)
If the base object is a Java language array, attempts to set the value at the given index with the given value. The index is specified by theproperty
argument, and coerced into an integer. If the coercion could not be performed, anIllegalArgumentException
is thrown. If the index is out of bounds, aPropertyNotFoundException
is thrown.If the base is a Java language array, the
propertyResolved
property of theELContext
object must be set totrue
by this resolver, before returning. If this property is nottrue
after this method is called, the caller can safely assume no value was set.If this resolver was constructed in read-only mode, this method will always throw
PropertyNotWritableException
.- Specified by:
setValue
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- The array to be modified. Only bases that are Java language arrays are handled by this resolver.property
- The index of the value to be set. Will be coerced into an integer.val
- The value to be set at the given index.- Throws:
java.lang.ClassCastException
- if the class of the specified element prevents it from being added to this array.java.lang.NullPointerException
- if context isnull
.java.lang.IllegalArgumentException
- if the property could not be coerced into an integer, or if some aspect of the specified element prevents it from being added to this array.PropertyNotWritableException
- if this resolver was constructed in read-only mode.PropertyNotFoundException
- if the given index is out of bounds for this array.ELException
- if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
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isReadOnly
public boolean isReadOnly(ELContext context, java.lang.Object base, java.lang.Object property)
If the base object is a Java language array, returns whether a call tosetValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object)
will always fail.If the base is a Java language array, the
propertyResolved
property of theELContext
object must be set totrue
by this resolver, before returning. If this property is nottrue
after this method is called, the caller should ignore the return value.If this resolver was constructed in read-only mode, this method will always return
true
. Otherwise, it returnsfalse
.- Specified by:
isReadOnly
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- The array to analyze. Only bases that are a Java language array are handled by this resolver.property
- The index of the element in the array to return the acceptable type for. Will be coerced into an integer, but otherwise ignored by this resolver.- Returns:
- If the
propertyResolved
property ofELContext
was set totrue
, thentrue
if calling thesetValue
method will always fail orfalse
if it is possible that such a call may succeed; otherwise undefined. - Throws:
PropertyNotFoundException
- if the given index is out of bounds for this array.java.lang.NullPointerException
- if context isnull
ELException
- if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
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getFeatureDescriptors
public java.util.Iterator<java.beans.FeatureDescriptor> getFeatureDescriptors(ELContext context, java.lang.Object base)
Always returnsnull
, since there is no reason to iterate through set set of all integers.The
getCommonPropertyType(javax.el.ELContext, java.lang.Object)
method returns sufficient information about what properties this resolver accepts.- Specified by:
getFeatureDescriptors
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- The array to analyze. Only bases that are a Java language array are handled by this resolver.- Returns:
null
.- See Also:
FeatureDescriptor
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getCommonPropertyType
public java.lang.Class<?> getCommonPropertyType(ELContext context, java.lang.Object base)
If the base object is a Java language array, returns the most general type that this resolver accepts for theproperty
argument. Otherwise, returnsnull
.Assuming the base is an array, this method will always return
Integer.class
. This is because arrays accept integers for their index.- Specified by:
getCommonPropertyType
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- The array to analyze. Only bases that are a Java language array are handled by this resolver.- Returns:
null
if base is not a Java language array; otherwiseInteger.class
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