PyJNIus

A Python module to access Java classes as Python classes using the Java Native Interface (JNI). Warning: the pypi name is now

pyjnius

jnius

Installation

pip install pyjnius

Quick overview

>>> from jnius import autoclass
>>> autoclass('java.lang.System').out.println('Hello world')
Hello world

>>> Stack = autoclass('java.util.Stack')
>>> stack = Stack()
>>> stack.push('hello')
>>> stack.push('world')
>>> print(stack.pop())
world
>>> print(stack.pop())
hello

Usage with python-for-android

• Get python-for-android
• Compile a distribution with kivy (PyJNIus will be automatically added)

Then, you can do this kind of things:

from time import sleep
from jnius import autoclass

Hardware = autoclass('org.renpy.android.Hardware')
print('DPI is', Hardware.getDPI())
Hardware.accelerometerEnable(True)
for x in xrange(20):
    print(Hardware.accelerometerReading())
    sleep(.1)

It will output something like:

I/python  ( 5983): Android kivy bootstrap done. __name__ is __main__
I/python  ( 5983): Run user program, change dir and execute main.py
I/python  ( 5983): DPI is 160
I/python  ( 5983): [0.0, 0.0, 0.0]
I/python  ( 5983): [-0.0095768067985773087, 9.3852710723876953, 2.2218191623687744]
I/python  ( 5983): [-0.0095768067985773087, 9.3948478698730469, 2.2218191623687744]
I/python  ( 5983): [-0.0095768067985773087, 9.3948478698730469, 2.2026655673980713]
I/python  ( 5983): [-0.028730420395731926, 9.4044246673583984, 2.2122423648834229]
I/python  ( 5983): [-0.019153613597154617, 9.3852710723876953, 2.2026655673980713]
I/python  ( 5983): [-0.028730420395731926, 9.3852710723876953, 2.2122423648834229]
I/python  ( 5983): [-0.0095768067985773087, 9.3852710723876953, 2.1835119724273682]
I/python  ( 5983): [-0.0095768067985773087, 9.3756942749023438, 2.1835119724273682]
I/python  ( 5983): [0.019153613597154617, 9.3948478698730469, 2.2122423648834229]
I/python  ( 5983): [0.038307227194309235, 9.3852710723876953, 2.2218191623687744]
I/python  ( 5983): [-0.028730420395731926, 9.3948478698730469, 2.2026655673980713]
I/python  ( 5983): [-0.028730420395731926, 9.3852710723876953, 2.2122423648834229]
I/python  ( 5983): [-0.038307227194309235, 9.3756942749023438, 2.2026655673980713]
I/python  ( 5983): [0.3926490843296051, 9.3086557388305664, 1.3311761617660522]
I/python  ( 5983): [-0.10534487664699554, 9.4331550598144531, 2.1068975925445557]
I/python  ( 5983): [0.26815059781074524, 9.3469638824462891, 2.3463177680969238]
I/python  ( 5983): [-0.1149216815829277, 9.3852710723876953, 2.31758713722229]
I/python  ( 5983): [-0.038307227194309235, 9.41400146484375, 1.8674772977828979]
I/python  ( 5983): [0.13407529890537262, 9.4235782623291016, 2.2026655673980713]

Advanced example

When you use

autoclass

from time import sleep
from jnius import MetaJavaClass, JavaClass, JavaMethod, JavaStaticMethod

class Hardware(JavaClass):
    metaclass = MetaJavaClass
    javaclass = 'org/renpy/android/Hardware'
    vibrate = JavaStaticMethod('(D)V')
    accelerometerEnable = JavaStaticMethod('(Z)V')
    accelerometerReading = JavaStaticMethod('()[F')
    getDPI = JavaStaticMethod('()I')
use that new class!
print('DPI is', Hardware.getDPI())
Hardware.accelerometerEnable()
for x in xrange(20):
    print(Hardware.accelerometerReading())
    sleep(.1)

You can use the

signatures

JavaMethod

JavaMultipleMethod

>>> String = autoclass('java.lang.String')
>>> dir(String)
['CASE_INSENSITIVE_ORDER', '__class__', '__cls_storage', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__javaclass__', '__javaconstructor__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__pyx_vtable__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'charAt', 'checkBounds', 'clone', 'codePointAt', 'codePointBefore', 'codePointCount', 'compareTo', 'compareToIgnoreCase', 'concat', 'contains', 'contentEquals', 'copyValueOf', 'empty', 'endsWith', 'equals', 'equalsIgnoreCase', 'finalize', 'format', 'getBytes', 'getChars', 'getClass', 'hashCode', 'indexOf', 'indexOfSupplementary', 'intern', 'isEmpty', 'join', 'lastIndexOf', 'lastIndexOfSupplementary', 'length', 'matches', 'nonSyncContentEquals', 'notify', 'notifyAll', 'offsetByCodePoints', 'regionMatches', 'registerNatives', 'replace', 'replaceAll', 'replaceFirst', 'split', 'startsWith', 'subSequence', 'substring', 'toCharArray', 'toLowerCase', 'toString', 'toUpperCase', 'trim', 'valueOf', 'wait']
>>> String.format.signatures()
[(['java/util/Locale', 'java/lang/String', 'java/lang/Object...'], 'java/lang/String'), (['java/lang/String', 'java/lang/Object...'], 'java/lang/String')]

Each pair contains the list of accepted arguments types, and the returned type.

Troubleshooting

Make sure a Java Development Kit (JDK) is installed on your operating system if you want to use PyJNIus on desktop. OpenJDK is known to work, and the Oracle Java JDK should work as well.

On windows, make sure

JAVA_HOME

jvm.dll

JAVA_HOME

Support

If you need assistance, you can ask for help on our mailing list:

• User Group : https://groups.google.com/group/kivy-users
• Email : [email protected]

We also have a Discord server:

https://chat.kivy.org/

Contributing

We love pull requests and discussing novel ideas. Check out our contribution guide and feel free to improve PyJNIus.

The following mailing list and IRC channel are used exclusively for discussions about developing the Kivy framework and its sister projects:

• Dev Group : https://groups.google.com/group/kivy-dev
• Email : [email protected]

License

PyJNIus is released under the terms of the MIT License. Please refer to the LICENSE file for more information.

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