org.codehaus.groovy.runtime
Class NullObject

Field Summary
 NullObject INSTANCE
           
 
Constructor Summary
NullObject()
            private constructor
 
Method Summary
Object asType(Class c)
           Type conversion method for null.
Object clone()
           Since this is implemented as a singleton, we should avoid the use of the clone method
boolean equals(Object to)
           null is only equal to null
static NullObject getNullObject()
           get the NullObject reference
Object getProperty(String property)
           Tries to get a property on null, which will always fail
int hashCode()
          
Object invokeMethod(String name, Object args)
           Tries to invoke a method on null, which will always fail
boolean is(Object other)
           The method "is" is used to test for equal references.
Iterator iterator()
           iterator() method to be able to iterate on null.
Object plus(String s)
           Allows to add a String to null.
void setProperty(String property, Object newValue)
           Tries to set a property on null, which will always fail
String toString()
          
 

Constructor Detail

NullObject

NullObject()
private constructor


Method Detail

asType

public Object asType(Class c)
Type conversion method for null.
param:
c - the class to convert to
return:
always null


clone

public Object clone()
Since this is implemented as a singleton, we should avoid the use of the clone method


equals

public boolean equals(Object to)
null is only equal to null
param:
to - the reference object with which to compare
return:
- true if this object is the same as the to argument


getNullObject

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


getProperty

public Object getProperty(String property)
Tries to get a property on null, which will always fail
param:
property - the property to get
return:
a NPE


hashCode

public int hashCode()


invokeMethod

public Object invokeMethod(String name, Object args)
Tries to invoke a method on null, which will always fail
param:
name the name of the method to invoke
param:
args - arguments to the method
return:
a NPE


is

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


iterator

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


plus

public Object plus(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.
param:
s - the String to concatenate
return:
the concatenated string


setProperty

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


toString

public String toString()