Package jakarta.el

Class LambdaExpression

java.lang.Object
jakarta.el.LambdaExpression
public class LambdaExpression extends Object
Encapsulates a parameterized ValueExpression.

A LambdaExpression is a representation of the Jakarta Expression Language 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 Jakarta Expression Language expression containing a Lambda expression is evaluated.

A LambdaExpression can be invoked by calling invoke(jakarta.el.ELContext, java.lang.Object...), with an ELContext and a list of the actual arguments. Alternately, a LambdaExpression can be invoked without passing a ELContext, in which case the ELContext previously set by calling setELContext(jakarta.el.ELContext) will be used. The evaluation of the ValueExpression in the body uses the ELContext to resolve references to the parameters, and to evaluate the lambda expression. The result of the evaluation is returned.

See Also:

  • Constructor Details

    • LambdaExpression

      public LambdaExpression(List<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 Details

    • setELContext

      public void setELContext(ELContext context)
      Set the ELContext to use in evaluating the LambdaExpression. The ELContext must to be set prior to the invocation of the LambdaExpression, unless it is supplied with invoke(jakarta.el.ELContext, java.lang.Object...).
      Parameters:
      context - The ELContext to use in evaluating the LambdaExpression.

    • invoke

      public Object invoke(ELContext elContext, 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 The ELContext set by setELContext(jakarta.el.ELContext) is ignored.
      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
      NullPointerException - is elContext is null

    • invoke

      public Object invoke(Object... args)
      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.

      The ELContext set by setELContext(jakarta.el.ELContext) is used in the evaluation of the lambda Expression.
      Parameters:
      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