godot-docs/classes/class_javaclasswrapper.rst

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.. _class_JavaClassWrapper:

JavaClassWrapper
================

**Inherits:** :ref:`Object<class_Object>`

Provides access to the Java Native Interface.

.. rst-class:: classref-introduction-group

Description
-----------

The JavaClassWrapper singleton provides a way for the Godot application to send and receive data through the `Java Native Interface <https://developer.android.com/training/articles/perf-jni>`__ (JNI).

\ **Note:** This singleton is only available in Android builds.

::

    var LocalDateTime = JavaClassWrapper.wrap("java.time.LocalDateTime")
    var DateTimeFormatter = JavaClassWrapper.wrap("java.time.format.DateTimeFormatter")

    var datetime = LocalDateTime.now()
    var formatter = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss")

    print(datetime.format(formatter))

\ **Warning:** When calling Java methods, be sure to check :ref:`get_exception()<class_JavaClassWrapper_method_get_exception>` to check if the method threw an exception.

.. rst-class:: classref-introduction-group

Tutorials
---------

- :doc:`Integrating with Android APIs <../tutorials/platform/android/javaclasswrapper_and_androidruntimeplugin>`

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Methods
-------

.. table::
   :widths: auto

   +-------------------------------------+-------------------------------------------------------------------------------------------+
   | :ref:`JavaObject<class_JavaObject>` | :ref:`get_exception<class_JavaClassWrapper_method_get_exception>`\ (\ )                   |
   +-------------------------------------+-------------------------------------------------------------------------------------------+
   | :ref:`JavaClass<class_JavaClass>`   | :ref:`wrap<class_JavaClassWrapper_method_wrap>`\ (\ name\: :ref:`String<class_String>`\ ) |
   +-------------------------------------+-------------------------------------------------------------------------------------------+

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----

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Method Descriptions
-------------------

.. _class_JavaClassWrapper_method_get_exception:

.. rst-class:: classref-method

:ref:`JavaObject<class_JavaObject>` **get_exception**\ (\ ) :ref:`🔗<class_JavaClassWrapper_method_get_exception>`

Returns the Java exception from the last call into a Java class. If there was no exception, it will return ``null``.

\ **Note:** This method only works on Android. On every other platform, this method will always return ``null``.

.. rst-class:: classref-item-separator

----

.. _class_JavaClassWrapper_method_wrap:

.. rst-class:: classref-method

:ref:`JavaClass<class_JavaClass>` **wrap**\ (\ name\: :ref:`String<class_String>`\ ) :ref:`🔗<class_JavaClassWrapper_method_wrap>`

Wraps a class defined in Java, and returns it as a :ref:`JavaClass<class_JavaClass>` :ref:`Object<class_Object>` type that Godot can interact with.

When wrapping inner (nested) classes, use ``$`` instead of ``.`` to separate them. For example, ``JavaClassWrapper.wrap("android.view.WindowManager$LayoutParams")`` wraps the **WindowManager.LayoutParams** class.

\ **Note:** To invoke a constructor, call a method with the same name as the class. For example:

::

    var Intent = JavaClassWrapper.wrap("android.content.Intent")
    var intent = Intent.Intent()

\ **Note:** This method only works on Android. On every other platform, this method does nothing and returns an empty :ref:`JavaClass<class_JavaClass>`.

.. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
.. |required| replace:: :abbr:`required (This method is required to be overridden when extending its base class.)`
.. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`
.. |vararg| replace:: :abbr:`vararg (This method accepts any number of arguments after the ones described here.)`
.. |constructor| replace:: :abbr:`constructor (This method is used to construct a type.)`
.. |static| replace:: :abbr:`static (This method doesn't need an instance to be called, so it can be called directly using the class name.)`
.. |operator| replace:: :abbr:`operator (This method describes a valid operator to use with this type as left-hand operand.)`
.. |bitfield| replace:: :abbr:`BitField (This value is an integer composed as a bitmask of the following flags.)`
.. |void| replace:: :abbr:`void (No return value.)`