Eager to get started? This page will give you a good introduction to Pyjnius. It assumes you have already Pyjnius installed. If you do not, head over the Installation section.

A minimal example#

A minimal Pyjnius example looks something like this:

from jnius import autoclass

Stack = autoclass('java.util.Stack')
stack = Stack()

print stack.pop() # --> 'world'
print stack.pop() # --> 'hello'

Just save it as test.py (or something similar) and run it with your Python interpreter. Make sure not to call your application jnius.py because it would conflict with Pyjnius itself:

$ python test.py

To load nested java classes, use the “$” separator as so:

version = autoclass("android.os.Build$VERSION")
base_os = version.BASE_OS

Automatic recursive inspection#

Pyjnius uses Java reflection to give you a new autoclass() if the return type is not a native type. Let’s see this example:

System = autoclass('java.lang.System')
System.out.println('Hello World')

We only declared the first System class, but we are able to use all the static fields and methods naturally. Let’s go deeper:

>>> System = autoclass('java.lang.System')
>>> System
<class 'jnius.java.lang.System'>
>>> System.out
<java.io.PrintStream at 0x234df50 jclass=java/io/PrintStream jself=37921360>
>>> System.out.println
<jnius.JavaMethodMultiple object at 0x236adb8>

The recursive reflection always gives you an appropriate object that reflects the returned Java object.