[Java] Class NullObject
- org.codehaus.groovy.runtime.NullObject
public class NullObject extends GroovyObjectSupport
Methods Summary
| Type Params | Return Type | Name and description |
|---|---|---|
public boolean |
asBoolean()A null object always coerces to false. | |
public Object |
asType(Class c)Type conversion method for null. | |
public Object |
clone()Since this is implemented as a singleton, we should avoid the use of the clone method | |
public boolean |
equals(Object to)null is only equal to null | |
public static NullObject |
getNullObject()get the NullObject reference | |
public Object |
getProperty(String property)Tries to get a property on null, which will always fail | |
public int |
hashCode() | |
public Object |
invokeMethod(String name, Object args)Tries to invoke a method on null, which will always fail | |
public boolean |
is(Object other)The method "is" is used to test for equal references. | |
public Iterator |
iterator()iterator() method to be able to iterate on null. | |
public Object |
plus(String s)Allows to add a String to null. | |
public Object |
plus(Object o)Fallback for null+null. | |
public void |
setProperty(String property, Object newValue)Tries to set a property on null, which will always fail | |
public String |
toString() | |
<T> | public T |
with(Closure<T> closure)Allows the closure to be called for NullObject |
Inherited Methods Summary
| Methods inherited from class | Name |
|---|---|
class GroovyObjectSupport | getMetaClass, setMetaClass |
Method Detail
public boolean asBoolean()
A null object always coerces to false.
- Returns:
- false
public Object asType(Class c)
Type conversion method for null.
- Parameters:
-
c- - the class to convert to
- Returns:
- always null
public Object clone()
Since this is implemented as a singleton, we should avoid the use of the clone method
public boolean equals(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
public static NullObject getNullObject()
get the NullObject reference
- Returns:
- the null object
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
public int hashCode()
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
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
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
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
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
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
public String toString()
<T> public 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
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Licensed under the Apache license.
https://docs.groovy-lang.org/3.0.7/html/gapi/org/codehaus/groovy/runtime/NullObject.html