How to init myLongArray as array(java.lang.Long, [myLongValue])

If I read a value from OPC into newValue I get array(java.lang.Long, [1L])

oldQualifiedValue = system.opc.readValue(server, path)
newValue = oldQualifiedValue.getValue()
print str(newValue) gives me array(java.lang.Long, [1L])

someNumber = 1
myValue = []
print str(myValue) gives me [1L]

How do initialize myLongArray as array(java.lang.Long, [myLongValue])

It is poorly documented, but you need jython’s jarray module. Keep in mind that java arrays are not appendable–the jarray module lets you turn a list into a fixed-length java array.


FWIW, Jython is really good at auto-converting lists into java arrays for methods when its signature is unambiguous. That’s why jarray is rarely needed.

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The jarray module exports two functions: 
   array(sequence, type) 
   zeros(length, type)

What readValue returned was array(type, sequence)

Also, how do I use this in the ignition scripting. I get the exception array not defined.

import jarray

arrayOfBytes = jarray.array([1,2,5,8,9,10], 'b')
print repr(arrayOfBytes)

This seems to be what I need too.
I have a base64 string that I decoded:

message_bytes = base64.b64decode(base64_str)

And made into a bytearray:

bytes_array = list(bytearray(message_bytes))

And then I wish to make it into a Java bytes array:

jarray_version = jarray.array(bytes_array, "b")

However I get error:
OverflowError: value too large for byte

Do you know how to avoid this? Or an alternative way to turn bse64 str into Java byte array

from com.inductiveautomation.ignition.common import Base64
bytes = Base64.decode(string)

No muss, no fuss.