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Project description


Supercharged Java access from Python.

Built on pyjnius and jgo.

Use Java classes from Python

>>> import scyjava, jnius
>>> System = jnius.autoclass('java.lang.System')
>>> System.getProperty('java.version')

To pass parameters to the JVM, such as an increased max heap size:

>>> import scyjava_config
>>> scyjava_config.add_options('-Xmx6g')
>>> import scyjava, jnius
>>> Runtime = jnius.autoclass('java.lang.Runtime')
>>> Runtime.getRuntime().maxMemory() / 2**30

See the Pyjnius documentation for more about calling Java from Python.

Use Maven artifacts from remote repositories

From Maven Central

>>> import sys; sys.version_info
sys.version_info(major=3, minor=6, micro=5, releaselevel='final', serial=0)
>>> import scyjava_config
>>> scyjava_config.add_endpoints('org.python:jython-standalone:2.7.1')
>>> import scyjava, jnius
>>> jython = jnius.autoclass('org.python.util.jython')
>>> jython.main([])
Jython 2.7.1 (default:0df7adb1b397, Jun 30 2017, 19:02:43)
[OpenJDK 64-Bit Server VM (JetBrains s.r.o)] on java1.8.0_152-release
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys; sys.version_info
sys.version_info(major=2, minor=7, micro=1, releaselevel='final', serial=0)

From other Maven repositories

>>> import scyjava_config
>>> scyjava_config.add_repositories({'scijava.public': ''})
>>> scyjava_config.add_endpoints('net.imagej:imagej:2.0.0-rc-65')
>>> import scyjava, jnius
>>> System = jnius.autoclass('java.lang.System')
>>> System.setProperty('java.awt.headless', 'true')
>>> ImageJ = jnius.autoclass('net.imagej.ImageJ')
>>> ij = ImageJ()
>>> formula = "10 * (Math.cos(0.3*p[0]) + Math.sin(0.3*p[1]))"
>>> blank = ij.op().create().img([64, 16])
>>> sinusoid = ij.op().image().equation(blank, formula)
>>> print(ij.op().image().ascii(sinusoid))
 ...,--++oooo++--,... ...,--++oooo++--,... ...,--++oooo++-,,...
   ..,--++++++--,..     ..,--++o+++--,..     .,,--++o+++--,..
   ..,,-++++++-,,.      ..,,-++++++-,,.      ..,--++++++-,,.
    .,,--++++--,,.       .,,--++++--,,.       .,,--++++--,..
    .,,--++++--,,.       .,,-+++++--,,.       .,,-+++++--,,.
   ..,--++++++--,..     ..,--++++++--,..     ..,--++++++-,,..
  ..,,-++oooo++-,,..   ..,,-++oooo++-,,..   ..,,-++ooo+++-,,..

See the jgo documentation for more about Maven endpoints.

Convert between Python and Java data structures

Convert Java collections to Python

>>> import scyjava, jnius
>>> System = jnius.autoclass('java.lang.System')
>>> props = System.getProperties()
>>> props
<java.util.Properties at 0x10dc2daf0 jclass=java/util/Properties jself=<LocalRef obj=0x7fcfefd34b20 at 0x10dc371f0>>
>>> [k for k in props]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'java.util.Properties' object is not iterable
>>> [k for k in scyjava.to_python(props) if k.startswith('java.vm.')]
['java.vm.version', 'java.vm.vendor', '', '', 'java.vm.specification.vendor', 'java.vm.specification.version', '']

Convert Python collections to Java

>>> squares = [n**2 for n in range(1, 10)]
>>> squares
[1, 4, 9, 16, 25, 36, 49, 64, 81]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'stream'
>>> scyjava.to_java(squares).stream()
< at 0x119d8ba40 jclass=java/util/stream/Stream jself=<LocalRef obj=0x7fcfefd34810 at 0x10dc37810>>

Introspect Java classes

>>> import scyjava
>>> NumberClass = scyjava.jclass('java.lang.Number')
>>> NumberClass
<Class at 0x10dca89e8 jclass=java/lang/Class jself=<LocalRef obj=0x7fcfefd33420 at 0x10dc37a30>>
>>> NumberClass.getName()
>>> NumberClass.isInstance(scyjava.to_java(5))
>>> NumberClass.isInstance(scyjava.to_java('Hello'))

Available functions

>>> import scyjava
>>> help(scyjava.convert)
        Return whether the given data object is a Java object.

        Obtain a Java class object.

        :param data: The object from which to glean the class.
        Supported types include:
        A. Name of a class to look up, analogous to
        B. A jnius.MetaJavaClass object e.g. from jnius.autoclass, analogous to
        C. A jnius.JavaClass object e.g. instantiated from a jnius.MetaJavaClass,
        analogous to "Hello".getClass().
        :returns: A java.lang.Class object, suitable for use with reflection.
        :raises TypeError: if the argument is not one of the aforementioned types.

        Recursively convert a Python object to a Java object.
        :param data: The Python object to convert.
        Supported types include:
        * str -> String
        * bool -> Boolean
        * int -> Integer, Long or BigInteger as appropriate
        * float -> Float, Double or BigDecimal as appropriate
        * dict -> LinkedHashMap
        * set -> LinkedHashSet
        * list -> ArrayList
        :returns: A corresponding Java object with the same contents.
        :raises TypeError: if the argument is not one of the aforementioned types.

        Recursively convert a Java object to a Python object.
        :param data: The Java object to convert.
        Supported types include:
        * String, Character -> str
        * Boolean -> bool
        * Byte, Short, Integer, Long, BigInteger -> int
        * Float, Double, BigDecimal -> float
        * Map -> (dict-like)
        * Set -> (set-like)
        * List -> (list-like)
        * Collection ->
        * Iterable ->
        * Iterator ->
        :returns: A corresponding Python object with the same contents.
        :raises TypeError: if the argument is not one of the aforementioned types.

Project details

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