[Java] Class NullObject
- org.codehaus.groovy.runtime.NullObject
Properties Summary
Type | Name and description |
---|---|
Object |
property |
Methods Summary
Type Params | Return Type | Name and 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(String s) Allows to add a String to null. | |
Object |
plus(Object o) Fallback for null+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 |
Inherited Methods Summary
Methods inherited from class | Name |
---|---|
class GroovyObjectSupport | getMetaClass, getProperty, invokeMethod, setMetaClass, setProperty |
Property Detail
Object property
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/2.5.14/html/gapi/org/codehaus/groovy/runtime/NullObject.html