javax.el
Class LambdaExpression

java.lang.Object
  javax.el.LambdaExpression

public class LambdaExpression
extends java.lang.Object

Encapsulates a parameterized ValueExpression.

A LambdaExpression is a representation of the EL Lambda expression syntax. It consists of a list of the formal parameters and a body, represented by a ValueExpression. The body can be any valid Expression, including another LambdaExpression.

A LambdaExpression is created when an EL expression containing a Lambda expression is evaluated.

A LambdaExpression can be invoked by calling invoke(javax.el.ELContext, java.lang.Object...), with an ELContext and a list of the actual arguments. The evaluation of the ValueExpression in the body uses the ELContext to resolve references to the parameters. The result of the evaluation is returned.

See Also:

ELContext.getLambdaArgument(java.lang.String), ELContext.enterLambdaScope(java.util.Map), ELContext.exitLambdaScope()

Constructor Summary

LambdaExpression(java.util.List<java.lang.String> formalParameters, ValueExpression expression)
Creates a new LambdaExpression.

Method Summary

java.lang.Object

invoke(ELContext elContext, java.lang.Object... args) Invoke the encapsulated Lambda expression.

Methods inherited from class java.lang.Object

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

Constructor Detail

LambdaExpression

public LambdaExpression(java.util.List<java.lang.String> formalParameters,
                        ValueExpression expression)

Creates a new LambdaExpression.

Parameters:

formalParameters - The list of String representing the formal parameters.

expression - The ValueExpression representing the body.

Method Detail

invoke

public java.lang.Object invoke(ELContext elContext,
                               java.lang.Object... args)
                        throws ELException

Invoke the encapsulated Lambda expression.

The supplied arguments are matched, in the same order, to the formal parameters. If there are more arguments than the formal parameters, the extra arguments are ignored. If there are less arguments than the formal parameters, an ELException is thrown.

The actual Lambda arguments are added to the ELContext and are available during the evaluation of the Lambda expression. They are removed after the evaluation.

Parameters:

elContext - The ELContext used for the evaluation of the expression

args - The arguments to invoke the Lambda expression. For calls with no arguments, an empty array must be provided. A Lambda argument can be null.

Returns:

The result of invoking the Lambda expression

Throws:

ELException - if not enough arguments are provided