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org.codehaus.groovy.runtime
[Java] Class NullObject

java.lang.Object
  groovy.lang.GroovyObjectSupport
      org.codehaus.groovy.runtime.NullObject

public class NullObject
extends GroovyObjectSupport
Method Summary
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.String s)

Allows to add a String to null.

java.lang.Object plus(java.lang.Object o)

Fallback for null+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()

 
Methods inherited from class GroovyObjectSupport
getMetaClass, getProperty, invokeMethod, setMetaClass, setProperty
 
Methods inherited from class java.lang.Object
java.lang.Object#wait(long, int), java.lang.Object#wait(long), java.lang.Object#wait(), java.lang.Object#equals(java.lang.Object), java.lang.Object#toString(), java.lang.Object#hashCode(), java.lang.Object#getClass(), java.lang.Object#notify(), java.lang.Object#notifyAll()
 

Method Detail

asBoolean

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

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

clone

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

equals

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

getNullObject

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

hashCode

public int hashCode()

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

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

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

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

toString

public java.lang.String toString()

 

Groovy Documentation