Class 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).
    Jody Garnett (Refractions Research, Inc.), Martin Desruisseaux (Geomatys)
    See Also:
    Serialized Form
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Object accept​(ExpressionVisitor visitor, Object extraData)
      Accepts a visitor.
      Object evaluate​(Object object)
      Returns null.
      <T> T evaluate​(Object object, Class<T> context)
      Returns null.
      String toString()
      Returns a string representation of this expression.
      • Methods inherited from class Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Method Detail

      • evaluate

        public Object evaluate​(Object object)
        Returns null.
        Specified by:
        evaluate in interface Expression
        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.
        object - The object to evaluate the expression against.
        context - The type of the resulting value of the expression.
        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.
        toString in class Object