javax.el

Class ValueExpression

java.lang.Object

javax.el.Expression

javax.el.ValueExpression

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

JspValueExpression, ValueExpressionImpl, ValueExpressionLiteral

public abstract class ValueExpression
extends Expression

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ValueExpression()

Method Summary

Modifier and Type	Method and Description
abstract Class<?>	getExpectedType()
abstract Class<?>	getType(ELContext context)
abstract Object	getValue(ELContext context)
ValueReference	getValueReference(ELContext context)
abstract boolean	isReadOnly(ELContext context)
abstract void	setValue(ELContext context, Object value)

Methods inherited from class javax.el.Expression

equals, getExpressionString, hashCode, isLiteralText

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueExpression

public ValueExpression()

Method Detail

getValue

public abstract Object getValue(ELContext context)

Parameters:

context - The EL context for this evaluation

Returns:

The result of evaluating this value expression

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If a property/variable resolution failed because no match was found or a match was found but was not readable

ELException - Wraps any exception throw whilst resolving a property or variable

setValue

public abstract void setValue(ELContext context,
                              Object value)

Parameters:

context - The EL context for this evaluation

value - The value to set the property to which this value expression refers

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If a property/variable resolution failed because no match was found

PropertyNotWritableException - If a property/variable resolution failed because a match was found but was not writable

ELException - Wraps any exception throw whilst resolving a property or variable

isReadOnly

public abstract boolean isReadOnly(ELContext context)

Parameters:

context - The EL context for this evaluation

Returns:

true if this expression is read only otherwise false

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If a property/variable resolution failed because no match was found or a match was found but was not readable

ELException - Wraps any exception throw whilst resolving a property or variable

getType

public abstract Class<?> getType(ELContext context)

Parameters:

context - The EL context for this evaluation

Returns:

The type of the result of this value expression

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If a property/variable resolution failed because no match was found or a match was found but was not readable

ELException - Wraps any exception throw whilst resolving a property or variable

getExpectedType

public abstract Class<?> getExpectedType()

getValueReference

public ValueReference getValueReference(ELContext context)

Parameters:

context - The EL context for this evaluation

Returns:

This default implementation always returns null

Since:

EL 2.2