Package org.codehaus.groovy.runtime

Class NullObject

java.lang.Object
groovy.lang.GroovyObjectSupport
org.codehaus.groovy.runtime.NullObject
All Implemented Interfaces:
GroovyObject
public class NullObject
extends GroovyObjectSupport

  • Method Summary

    Modifier and Type Method Description
    boolean asBoolean()
    A null object always coerces to false.
    java.lang.Object asType​(java.lang.Class c)
    Type conversion method for null.
    java.lang.Object clone()
    Since this is implemented as a singleton, we should avoid the use of the clone method
    boolean equals​(java.lang.Object to)
    null is only equal to null
    static NullObject getNullObject()
    get the NullObject reference
    java.lang.Object getProperty​(java.lang.String property)
    Tries to get a property on null, which will always fail
    int hashCode()  
    java.lang.Object invokeMethod​(java.lang.String name, java.lang.Object args)
    Tries to invoke a method on null, which will always fail
    boolean is​(java.lang.Object other)
    The method "is" is used to test for equal references.
    java.util.Iterator iterator()
    iterator() method to be able to iterate on null.
    java.lang.Object plus​(java.lang.Object o)
    Fallback for null+null.
    java.lang.Object plus​(java.lang.String s)
    Allows to add a String to null.
    void setProperty​(java.lang.String property, java.lang.Object newValue)
    Tries to set a property on null, which will always fail
    java.lang.String toString()  
    <T> T with​(Closure<T> closure)
    Allows the closure to be called for NullObject

    Methods inherited from class groovy.lang.GroovyObjectSupport

    getMetaClass, setMetaClass

    Methods inherited from class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait

  • Method Details

    • getNullObject

      public static NullObject getNullObject()
      get the NullObject reference
      Returns:
      the null object

    • clone

      public java.lang.Object clone()
      Since this is implemented as a singleton, we should avoid the use of the clone method
      Overrides:
      clone in class java.lang.Object

    • getProperty

      public java.lang.Object getProperty​(java.lang.String property)
      Tries to get a property on null, which will always fail
      Parameters:
      property - - the property to get
      Returns:
      a NPE

    • with

      public <T> T with​(Closure<T> closure)
      Allows the closure to be called for NullObject
      Parameters:
      closure - the closure to call on the object
      Returns:
      result of calling the closure

    • setProperty

      public void setProperty​(java.lang.String property, java.lang.Object newValue)
      Tries to set a property on null, which will always fail
      Parameters:
      property - - the proprty to set
      newValue - - the new value of the property

    • invokeMethod

      public java.lang.Object invokeMethod​(java.lang.String name, java.lang.Object args)
      Tries to invoke a method on null, which will always fail
      Parameters:
      name - the name of the method to invoke
      args - - arguments to the method
      Returns:
      a NPE

    • equals

      public boolean equals​(java.lang.Object to)
      null is only equal to null
      Overrides:
      equals in class java.lang.Object
      Parameters:
      to - - the reference object with which to compare
      Returns:
      - true if this object is the same as the to argument

    • iterator

      public java.util.Iterator iterator()
      iterator() method to be able to iterate on null. Note: this part is from Invoker
      Returns:
      an iterator for an empty list

    • plus

      public java.lang.Object plus​(java.lang.String s)
      Allows to add a String to null. The result is concatenated String of the result of calling toString() on this object and the String in the parameter.
      Parameters:
      s - - the String to concatenate
      Returns:
      the concatenated string

    • plus

      public java.lang.Object plus​(java.lang.Object o)
      Fallback for null+null. The result is always a NPE. The plus(String) version will catch the case of adding a non null String to null.
      Parameters:
      o - - the Object
      Returns:
      nothing

    • is

      public boolean is​(java.lang.Object other)
      The method "is" is used to test for equal references. This method will return true only if the given parameter is null
      Parameters:
      other - - the object to test
      Returns:
      true if other is null

    • asType

      public java.lang.Object asType​(java.lang.Class c)
      Type conversion method for null.
      Parameters:
      c - - the class to convert to
      Returns:
      always null

    • asBoolean

      public boolean asBoolean()
      A null object always coerces to false.
      Returns:
      false

    • toString

      public java.lang.String toString()
      Overrides:
      toString in class java.lang.Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class java.lang.Object