PyJNIus is a Python library for accessing Java classes using the Java Native Interface (JNI).
PyJNIus is managed by the Kivy Team and can be used with python-for-android.
It can also be used independently of Kivy, on desktop and mobile platforms.
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pip install pyjnius
>>> 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- Get python-for-android
- Compile a distribution with kivy (PyJNIus will be automatically added)
Then, you can do this kind of thing:
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 range(20):
print(Hardware.accelerometerReading())
sleep(0.1)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]
When you use autoclass, it will discover all the methods and fields of the
class and resolve them. You may want to declare and use only what you
need. The previous example can be done manually as follows:
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 range(20):
print(Hardware.accelerometerReading())
sleep(0.1)You can use the signatures method of JavaMethod and JavaMultipleMethod, to inspect the discovered signatures of a method of an object
>>> String = autoclass('java.lang.String')
>>> dir(String)
['CASE_INSENSITIVE_ORDER', '__class__', '_JavaClass__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.
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 points to your Java installation, so PyJNIus
can locate the jvm.dll file allowing it to start Java. This shouldn't be
necessary on macOS and Linux, but in case PyJNIus fails to find it, setting
JAVA_HOME should help.
PyJNIus is MIT licensed, actively developed by a great community and is supported by many projects managed by the Kivy Organization.
Documentation for this repository.
Are you having trouble using PyJNIus or any of its related projects in the Kivy ecosystem? Is there an error you don’t understand? Are you trying to figure out how to use it? We have volunteers who can help!
The best channels to contact us for support are listed in the latest Contact Us document.
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