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.
  `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(Object o)`
  Fallback for null+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()`
  `<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 Object clone()
    Since this is implemented as a singleton, we should avoid the use of the clone method
    Overrides:
      `clone` in class `Object`

  - ### getProperty

    public Object getProperty(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(String property, 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 Object invokeMethod(String name, 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(Object to)
    null is only equal to null
    Overrides:
      `equals` in class `Object`
    Parameters:
      `to` - - the reference object with which to compare
    Returns:
      - true if this object is the same as the to argument

  - ### iterator

    public 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 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.
    Parameters:
      `s` - - the String to concatenate
    Returns:
      the concatenated string

  - ### plus

    public Object plus(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(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 Object asType(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 String toString()
    Overrides:
      `toString` in class `Object`

  - ### hashCode

    public int hashCode()
    Overrides:
      `hashCode` in class `Object`