Fix #2612 NPE when trying to import classes

[jamesmudd]

No description provided.

[Stewori]

This looks good to me. It is a simple change and I think we can safely accept it....

[jamesmudd]

Although this does resolve the issue I think @jeff5 may be able to propose a better fix. Discussion on http://bugs.jython.org/issue2612

[jeff5]

Looking at what this message would have been about (formatting of which produces the NPE), the foolproof choice is to get the string from the directory object itself. Fixed at https://hg.python.org/jython/rev/39b0bd0dcd01, I claim.

Just for now, I'm resisting the temptation to rationalise the surrounding code. :)

[tokunbo]

Did this issue return? My compiled class comes from scala source, instead of java-source in case that somehow matters.

├── testutils
│   ├── JMHTTPClient.class
│   └── JMHTTPClient.scala
└── worker.py

pikachu@POKEMONGYM ~/Forwardz/jmnarau $ java -jar ../usefuljars/jython-standalone-2.7.1.jar 
Jython 2.7.1 (default:0df7adb1b397, Jun 30 2017, 19:02:43) 
[Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.8.0_181
Type "help", "copyright", "credits" or "license" for more information.
>>> import testutils
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
java.lang.NullPointerException
        at org.python.core.PyString.encode_UnicodeEscape(PyString.java:339)
        at org.python.core.imp.loadFromSource(imp.java:627)
        at org.python.core.imp.find_module(imp.java:551)
        at org.python.core.imp.import_next(imp.java:838)
        at org.python.core.imp.import_module_level(imp.java:957)
        at org.python.core.imp.importName(imp.java:1057)
        at org.python.core.ImportFunction.__call__(__builtin__.java:1280)
        at org.python.core.PyObject.__call__(PyObject.java:450)
        at org.python.core.__builtin__.__import__(__builtin__.java:1232)
        at org.python.core.imp.importOne(imp.java:1076)
        at org.python.pycode._pyx1.f$0(<stdin>:1)
        at org.python.pycode._pyx1.call_function(<stdin>)
        at org.python.core.PyTableCode.call(PyTableCode.java:171)
        at org.python.core.PyCode.call(PyCode.java:18)
        at org.python.core.Py.runCode(Py.java:1614)
        at org.python.core.Py.exec(Py.java:1658)
        at org.python.util.PythonInterpreter.exec(PythonInterpreter.java:276)
        at org.python.util.InteractiveInterpreter.runcode(InteractiveInterpreter.java:131)
        at org.python.util.InteractiveInterpreter.runsource(InteractiveInterpreter.java:116)
        at org.python.util.InteractiveInterpreter.runsource(InteractiveInterpreter.java:62)
        at org.python.util.InteractiveConsole.push(InteractiveConsole.java:187)
        at org.python.util.InteractiveConsole._interact(InteractiveConsole.java:168)
        at org.python.util.InteractiveConsole.interact(InteractiveConsole.java:126)
        at org.python.util.jython.run(jython.java:419)
        at org.python.util.jython.main(jython.java:142)
java.lang.NullPointerException: java.lang.NullPointerException
>>> pikachu@POKEMONGYM ~/Forwardz/jmnarau $  sha1sum ../usefuljars/jython-standalone-2.7.1.jar 
942c3294840dc9dfb3528d775f4d02a6d57c421f  ../usefuljars/jython-standalone-2.7.1.jar
pikachu@POKEMONGYM ~/Forwardz/jmnarau $ 

[jeff5]

Not returned, just not fixed in 2.7.1 which you are clearly using.

Despite the best intentions, we have not released a 2.7.2 yet. You could wait or build your own snapshot JAR.

[tokunbo]

@jeff5 Ah, okay. Thanks. I can wait -^_^-
A suitable workaround I found, was to package the class in a jar then put the jar on the classpath.

pikachu@POKEMONGYM ~/Forwardz/jmnarau $ ~/Forwardz/jdk1.8.0_191/bin/jar cvf ./JMHTTPClient.jar testutils/JMHTTPClient.class
added manifest
adding: testutils/JMHTTPClient.class(in = 7055) (out= 3391)(deflated 51%)

Then, move away from that directory such that relative-dir testutils/JMHTTPClient.class does not exist. (or rename it or something, so only the jar can resolve testutils/JMHTTPClient)

pikachu@POKEMONGYM ~/Forwardz/jmnarau $ cd ..

Then.....

pikachu@POKEMONGYM ~/Forwardz $  java -cp ./jmnarau/JMHTTPClient.jar:./usefuljars/jython-standalone-2.7.1.jar:$( find /home/pikachu/Forwardz/scala-2.12.7 /home/pikachu/Forwardz/apache-jmeter-5.0 -name '*jar' | tr "\n" ":" ) org.python.util.jython
Jython 2.7.1 (default:0df7adb1b397, Jun 30 2017, 19:02:43) 
[Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.8.0_181
Type "help", "copyright", "credits" or "license" for more information.
>>> from testutils import JMHTTPClient
>>>

⚠️ It's important that the Java/Scala class is defined as being in a package of the same name as the folder-structure it was in when the jar command was ran. The Scala class above has the following as the first line: package testutils because the class is inside a folder named "testutils" within the jar. If it was "testutils/misc/clients/JMHTTPClient.class", then the package has to be package testutils.misc.clients