Package jakarta.el

Class OptionalELResolver

java.lang.Object

jakarta.el.ELResolver

jakarta.el.OptionalELResolver

public class OptionalELResolver
extends ELResolver

Defines property resolution, method invocation and type conversion behaviour on Optionals.

This resolver handles base objects that are instances of Optional.

This resolver is always a read-only resolver since Optional instances are immutable.

Constructor Summary

Constructors

Constructor	Description
OptionalELResolver()

Method Summary

Modifier and Type	Method	Description
<T> T	convertToType(ELContext context, Object obj, Class<T> type)	Converts the given object to the given type.
Class<?>	getCommonPropertyType(ELContext context, Object base)	Obtain the most common type that is acceptable for the given base object.
Class<?>	getType(ELContext context, Object base, Object property)	Obtain the most generally acceptable type that may be used to set the given property on the given object using the given context.
Object	getValue(ELContext context, Object base, Object property)	Obtain the value of the given property on the given object using the given context.
Object	invoke(ELContext context, Object base, Object method, Class<?>[] paramTypes, Object[] params)	Invokes a method on the the given object.
boolean	isReadOnly(ELContext context, Object base, Object property)	Determine if the given property on the given object is read-only using the given context.
void	setValue(ELContext context, Object base, Object property, Object value)	Set the value of the given property on the given object using the given context.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

OptionalELResolver

public OptionalELResolver()

Method Details

getValue

public Object getValue(ELContext context,
 Object base,
 Object property)

Obtain the value of the given property on the given object using the given context.

Specified by:

getValue in class ELResolver

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property whose value is to be returned

Returns:

If the base object is an Optional and Optional.isEmpty() returns true then the resulting value is null.

If the base object is an Optional, Optional.isPresent() returns true and the property is null then the resulting value is the result of calling Optional.get() on the base object.

If the base object is an Optional, Optional.isPresent() returns true and the property is not null then the resulting value is the result of calling ELResolver.getValue(ELContext, Object, Object) using the ELResolver obtained from ELContext.getELResolver() with the following parameters:

• The ELContext is the current context
• The base object is the result of calling Optional.get() on the current base object
• The property object is the current property object

If the base object is not an Optional then the return value is undefined.

getType

public Class<?> getType(ELContext context,
 Object base,
 Object property)

Obtain the most generally acceptable type that may be used to set the given property on the given object using the given context.

Specified by:

getType in class ELResolver

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property whose type is to be returned

Returns:

If the base object is an Optional this method always returns null since instances of this resolver are always read-only.

If the base object is not an Optional then the return value is undefined.

setValue

public void setValue(ELContext context,
 Object base,
 Object property,
 Object value)

Set the value of the given property on the given object using the given context.

If the base object is an Optional this method always throws a PropertyNotWritableException since instances of this resolver are always read-only.

Specified by:

setValue in class ELResolver

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property whose value is to be set

value - The value to set the property to

isReadOnly

public boolean isReadOnly(ELContext context,
 Object base,
 Object property)

Determine if the given property on the given object is read-only using the given context.

Specified by:

isReadOnly in class ELResolver

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property to be checked for read only status

Returns:

If the base object is an Optional this method always returns true since instances of this resolver are always read-only.

If the base object is not an Optional then the return value is undefined.

getCommonPropertyType

public Class<?> getCommonPropertyType(ELContext context,
 Object base)

Obtain the most common type that is acceptable for the given base object.

Specified by:

getCommonPropertyType in class ELResolver

Parameters:

context - The context in which the examination takes place

base - The object to examine

Returns:

If the base object is an Optional this method always returns Object.class.

If the base object is not an Optional then the return value is undefined.

convertToType

public <T> T convertToType(ELContext context,
 Object obj,
 Class<T> type)

Converts the given object to the given type.

Overrides:

convertToType in class ELResolver

Type Parameters:

T - The type to which the object should be converted

Parameters:

context - The EL context for this evaluation

obj - The object to convert

type - The type to which the object should be converted

Returns:

If the base object is an Optional and Optional.isEmpty() returns true then this method returns the result of coercing null to the requested type.

If the base object is an Optional and Optional.isPresent() returns true then this method returns the result of coercing Optional#get() to the requested type.

If the base object is not an Optional then the return value is undefined.

invoke

public Object invoke(ELContext context,
 Object base,
 Object method,
 Class<?>[] paramTypes,
 Object[] params)

Invokes a method on the the given object.

Overrides:

invoke in class ELResolver

Parameters:

context - The EL context for this evaluation

base - The base object on which the method is to be found

method - The method to invoke

paramTypes - The types of the parameters of the method to invoke

params - The parameters with which to invoke the method

Returns:

If the base object is an Optional and Optional.isEmpty() returns true then this method returns null.

If the base object is an Optional and Optional.isPresent() returns true then this method returns the result of invoking the specified method on the object obtained by calling Optional.get() with the specified parameters.

If the base object is not an Optional then the return value is undefined.