javax.servlet.jsp.el
Class Expression

java.lang.Object
  extended byjavax.servlet.jsp.el.Expression

public abstract class Expression
extends java.lang.Object

The abstract class for a prepared expression.

An instance of an Expression can be obtained via from an ExpressionEvaluator instance.

An Expression may or not have done a syntactic parse of the expression. A client invoking the evaluate() method should be ready for the case where ELParseException exceptions are raised.

Since:
2.0

Constructor Summary
Expression()
           
 
Method Summary
abstract  java.lang.Object evaluate(VariableResolver vResolver)
          Evaluates an expression that was previously prepared.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Expression

public Expression()
Method Detail

evaluate

public abstract java.lang.Object evaluate(VariableResolver vResolver)
                                   throws ELException
Evaluates an expression that was previously prepared. In some implementations preparing an expression involves full syntactic validation, but others may not do so. Evaluating the expression may raise an ELParseException as well as other ELExceptions due to run-time evaluation.

Parameters:
vResolver - A VariableResolver instance that can be used at runtime to resolve the name of implicit objects into Objects.
Returns:
The result of the expression evaluation.
Throws:
ELException - Thrown if the expression evaluation failed.


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