| java.lang.Object
 javax.el.ELResolver
javax.el.ListELResolver
| ListELResolver | | public class ListELResolver extends ELResolver (Code) | | Defines property resolution behavior on instances of
java.util.List .
This resolver handles base objects of type java.util.List.
It accepts any object as a property and coerces that object into an
integer index into the list. The resulting value is the value in the list
at that index.
This resolver can be constructed in read-only mode, which means that
ListELResolver.isReadOnly will always return true and
ListELResolver.setValue will always throw
PropertyNotWritableException.
ELResolvers are combined together using
CompositeELResolver s, to define rich semantics for evaluating
an expression. See the javadocs for
ELResolver for details.
See Also: CompositeELResolver
See Also: ELResolver
See Also: java.util.List
since:
JSP 2.1 |
| Constructor Summary | |
| public | ListELResolver()
Creates a new read/write ListELResolver. | | public | ListELResolver(boolean isReadOnly)
Creates a new ListELResolver whose read-only status is
determined by the given parameter. |
| Method Summary | |
| public Class | getCommonPropertyType(ELContext context, Object base)
If the base object is a list, returns the most general type that
this resolver accepts for the property argument.
Otherwise, returns null.
Assuming the base is a List, this method will always
return Integer.class. | | public Iterator<FeatureDescriptor> | getFeatureDescriptors(ELContext context, Object base)
Always returns null, since there is no reason to
iterate through set set of all integers.
The
ListELResolver.getCommonPropertyType method returns sufficient
information about what properties this resolver accepts.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list. | | public Class | getType(ELContext context, Object base, Object property)
If the base object is a list, returns the most general acceptable type
for a value in this list.
If the base is a List, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. | | public Object | getValue(ELContext context, Object base, Object property)
If the base object is a list, returns the value at the given index.
The index is specified by the property argument, and
coerced into an integer. | | public boolean | isReadOnly(ELContext context, Object base, Object property)
If the base object is a list, returns whether a call to
ListELResolver.setValue will always fail.
If the base is a List, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. | | public void | setValue(ELContext context, Object base, Object property, Object val)
If the base object is a list, attempts to set the value at the
given index with the given value. |
| ListELResolver | | public ListELResolver()(Code) | | Creates a new read/write ListELResolver.
|
| ListELResolver | | public ListELResolver(boolean isReadOnly)(Code) | | Creates a new ListELResolver whose read-only status is
determined by the given parameter.
Parameters:
isReadOnly - true if this resolver cannot modifylists; false otherwise. |
| getCommonPropertyType | | public Class getCommonPropertyType(ELContext context, Object base)(Code) | | If the base object is a list, returns the most general type that
this resolver accepts for the property argument.
Otherwise, returns null.
Assuming the base is a List, this method will always
return Integer.class. This is because Lists
accept integers as their index.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list to analyze. Only bases of type Listare handled by this resolver. null if base is not a List; otherwiseInteger.class. |
| getFeatureDescriptors | | public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base)(Code) | | Always returns null, since there is no reason to
iterate through set set of all integers.
The
ListELResolver.getCommonPropertyType method returns sufficient
information about what properties this resolver accepts.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list. Only bases of type List are handled by this resolver. null. |
| getType | | public Class getType(ELContext context, Object base, Object property)(Code) | | If the base object is a list, returns the most general acceptable type
for a value in this list.
If the base is a List, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true after this method is called, the caller
should ignore the return value.
Assuming the base is a List, this method will always
return Object.class. This is because Lists
accept any object as an element.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list to analyze. Only bases of type Listare handled by this resolver.
Parameters:
property - The index of the element in the list to return the acceptable type for. Will be coerced into an integer, but otherwise ignored by this resolver. If the propertyResolved property of ELContext was set to true, thenthe most general acceptable type; otherwise undefined.
throws:
PropertyNotFoundException - if the given index is out of bounds for this list.
throws:
NullPointerException - if context is null
throws:
ELException - if an exception was thrown while performingthe property or variable resolution. The thrown exceptionmust be included as the cause property of this exception, ifavailable. |
| getValue | | public Object getValue(ELContext context, Object base, Object property)(Code) | | If the base object is a list, returns the value at the given index.
The index is specified by the property argument, and
coerced into an integer. If the coercion could not be performed,
an IllegalArgumentException is thrown. If the index is
out of bounds, null is returned.
If the base is a List, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true after this method is called, the caller
should ignore the return value.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list to be analyzed. Only bases of type List are handled by this resolver.
Parameters:
property - The index of the value to be returned. Will be coercedinto an integer. If the propertyResolved property of ELContext was set to true, thenthe value at the given index or nullif the index was out of bounds. Otherwise, undefined.
throws:
IllegalArgumentException - if the property could not be coercedinto an integer.
throws:
NullPointerException - if context is null.
throws:
ELException - if an exception was thrown while performingthe property or variable resolution. The thrown exceptionmust be included as the cause property of this exception, ifavailable. |
| isReadOnly | | public boolean isReadOnly(ELContext context, Object base, Object property)(Code) | | If the base object is a list, returns whether a call to
ListELResolver.setValue will always fail.
If the base is a List, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true 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.
If a List was created using
java.util.Collections.unmodifiableList , this method must
return true. Unfortunately, there is no Collections API
method to detect this. However, an implementation can create a
prototype unmodifiable List and query its runtime type
to see if it matches the runtime type of the base object as a
workaround.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list to analyze. Only bases of type Listare handled by this resolver.
Parameters:
property - The index of the element in the list to return the acceptable type for. Will be coerced into an integer, but otherwise ignored by this resolver. If the propertyResolved property of ELContext was set to true, thentrue if calling the setValue methodwill always fail or false if it is possible thatsuch a call may succeed; otherwise undefined.
throws:
PropertyNotFoundException - if the given index is out of bounds for this list.
throws:
NullPointerException - if context is null
throws:
ELException - if an exception was thrown while performingthe property or variable resolution. The thrown exceptionmust be included as the cause property of this exception, ifavailable. |
| setValue | | public void setValue(ELContext context, Object base, Object property, Object val)(Code) | | If the base object is a list, attempts to set the value at the
given index with the given value. The index is specified by the
property argument, and coerced into an integer. If the
coercion could not be performed, an
IllegalArgumentException is thrown. If the index is
out of bounds, a PropertyNotFoundException is thrown.
If the base is a List, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true 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.
If a List was created using
java.util.Collections.unmodifiableList , this method must
throw PropertyNotWritableException. Unfortunately,
there is no Collections API method to detect this. However, an
implementation can create a prototype unmodifiable List
and query its runtime type to see if it matches the runtime type of
the base object as a workaround.
Parameters:
context - The context of this evaluation.
Parameters:
base - The list to be modified. Only bases of type List are handled by this resolver.
Parameters:
property - The index of the value to be set. Will be coercedinto an integer.
Parameters:
val - The value to be set at the given index.
throws:
ClassCastException - if the class of the specified element prevents it from being added to this list.
throws:
NullPointerException - if context is null, orif the value is null and this Listdoes not support null elements.
throws:
IllegalArgumentException - if the property could not be coercedinto an integer, or if some aspect of the specified element prevents it from being added to this list.
throws:
PropertyNotWritableException - if this resolver was constructedin read-only mode, or if the set operation is not supported by the underlying list.
throws:
PropertyNotFoundException - if the given index is out of bounds for this list.
throws:
ELException - if an exception was thrown while performingthe property or variable resolution. The thrown exceptionmust be included as the cause property of this exception, ifavailable. |
| Methods inherited from javax.el.ELResolver | abstract public Class getCommonPropertyType(ELContext context, Object base)(Code)(Java Doc)
abstract public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base)(Code)(Java Doc)
abstract public Class getType(ELContext context, Object base, Object property)(Code)(Java Doc)
abstract public Object getValue(ELContext context, Object base, Object property)(Code)(Java Doc)
abstract public boolean isReadOnly(ELContext context, Object base, Object property)(Code)(Java Doc)
abstract public void setValue(ELContext context, Object base, Object property, Object value)(Code)(Java Doc)
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