Package org.geotools.api.filter.expression

Class NilExpression

Object
NilExpression
All Implemented Interfaces:
Serializable, Expression
public final class NilExpression extends Object implements Expression, Serializable
Placeholder class used to represent a NIL expression, evaluates to null. This placeholder class allows data structures to avoid the use of null. Please note that Expression.NIL is not considered a Literal with value null (since the literal may have its value changed).
Author:
Jody Garnett (Refractions Research, Inc.), Martin Desruisseaux (Geomatys)
See Also:

  • Method Details

    • accept

      public Object accept(ExpressionVisitor visitor, Object extraData)
      Accepts a visitor.
      Specified by:
      accept in interface Expression

    • evaluate

      public Object evaluate(Object object)
      Returns null.
      Specified by:
      evaluate in interface Expression
      Returns:
      computed value

    • evaluate

      public <T> T evaluate(Object object, Class<T> context)
      Returns null.
      Specified by:
      evaluate in interface Expression
      Type Parameters:
      T - The type of the returned object.
      Parameters:
      object - The object to evaluate the expression against.
      context - The type of the resulting value of the expression.
      Returns:
      Evaluates the given expression based on the content of the given object an an instance of context.

    • toString

      public String toString()
      Returns a string representation of this expression.
      Overrides:
      toString in class Object