Python/Java Type Coercion¶
Jython handles type coercion automatically between Java and Python. However, it is useful to know the equivalency of Python types to Java types. The following table describes the equivalency of all types available in Python to their Java counterparts.
| Python Type | Jython PyObject Subclass | Java Type | Description |
|---|---|---|---|
int |
PyInteger |
java.lang.Integer |
Maps Python int to a Java Integer. |
float |
PyFloat |
java.lang.Double |
Maps Python float to Java Double. |
str |
PyString |
java.lang.String |
Maps Python str to Java String. |
bool |
PyBoolean |
java.lang.Boolean |
Maps Python True/False to Java Boolean |
None |
PyNone |
null |
Python None translates to Java null. |
long (Python 2 only) |
PyLong |
java.math.BigInteger |
Maps Python long to BigInteger. |
complex |
PyComplex |
org.python.core.PyComplex |
Represents complex numbers. |
list |
PyList |
java.util.List |
Maps Python list to Java List. |
tuple |
PyTuple |
java.util.List (immutable) |
Maps Python tuple to Java List but immutable. |
dict |
PyDictionary |
java.util.Map |
Maps Python dict to Java Map. |
set |
PySet |
java.util.Set |
Maps Python set to Java Set. |
frozenset |
PyFrozenSet |
java.util.Set (immutable) |
Maps Python frozenset to immutable Java Set. |
bytes |
PyString |
byte[] |
Maps Python bytes to Java byte[]. |
bytearray |
PyByteArray |
byte[] |
Mutable version of bytes mapped to byte[] |
memoryview |
PyMemoryView |
org.python.core.PyMemoryView |
Maps Python memoryview to Java PyMemoryView. |
function |
PyFunction |
org.python.core.PyFunction |
Python functions map to PyFunction in Java. |
method |
PyMethod |
org.python.core.PyMethod |
Python methods map to PyMethod. |
class |
PyClass |
org.python.core.PyClass |
Represents Python classes in Java. |
instance |
PyInstance |
org.python.core.PyInstance |
Maps Python instances to PyInstance. |
module |
PyModule |
org.python.core.PyModule |
Represents Python modules in Jython. |
callable (e.g., lambdas) |
PyCallable |
org.python.core.PyObject (callable) |
Maps callable Python objects like lambdas. |
object (general) |
PyObject |
java.lang.Object |
Generic Python object maps to Object in Java. |
iter (iterator) |
PyIterator |
java.util.Iterator |
Python iterator maps to Java Iterator. |
generator |
PyGenerator |
org.python.core.PyGenerator |
Maps Python generator objects. |
Exception |
PyException |
java.lang.Throwable |
Python exceptions map to Java Throwable. |
file (Python 2 only) |
PyFile |
java.io.InputStream/OutputStream |
Maps Python file objects to Java IO streams. |
ellipsis (...) |
PyEllipsis |
org.python.core.PyEllipsis |
Represents the ... object in Python. |
NotImplemented |
PyNotImplemented |
org.python.core.PyNotImplemented |
Represents NotImplemented in Python. |
slice |
PySlice |
org.python.core.PySlice |
Represents Python slices. |
buffer (Python 2 only) |
PyBuffer |
org.python.core.PyBuffer |
Represents Python buffer objects. |
type (metaclasses) |
PyType |
org.python.core.PyType |
Maps Python metaclasses (type) in Java. |
custom objects |
User-defined PyObject |
User-defined Java class or interface | Custom Python classes map to Java PyObject. |