How to converts Python None to Java null?

[everydaysayhello]

I didn't figure out how to convert Python 'None' to Java 'null', and I didn't find a place in the source code，can you help me?Thank you very much!

[pelson]

None is converted to null automatically:

>>> import jpype
>>> jpype.startJVM()
>>> jpype.java.util.Objects.isNull(None)
True

Is there something that I've not understood?

[Thrameos]

pelson is correct. As None is automatically converted to Java null there is little need specifically convert it most of the time.

The exception is cases in which you need a "typed" null which has a particular static type in order to resolve a method over load. Assuming you have MyObject.call(String) and MyObject.call(List) overloaded and for some reason null is a valid value. (which is incredibly bad practice)

import java
MyObject.call( java.lang.String@None )  # execute MyObject.call(String) with null
MyObject.call( java.util.List@None ) # execute MyObject.call(List) with null

Generally explicit nulls are unnecessary, but if you do then the casting operator @ can be used.

You may be tempted to just try to define a null handle with

null = java.lang.Object@None

Unfortunately, this null has a type of java.lang.Object so it won't resolve methods as expected.

>>> java.lang.String(null)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: No matching overloads found for constructor java.lang.String(java.lang.Object), options are:
        public java.lang.String(int[],int,int)
        public java.lang.String(byte[],int,int,int)
        public java.lang.String(byte[],int)
        public java.lang.String(byte[],int,int,java.lang.String) throws java.io.UnsupportedEncodingException
        ....