jni.py zapewnia automapping dla struktury jni.jval

class jvalue(ct.Union):
    z: jboolean = 0      # <-> int
    b: jbyte    = 0      # <-> int
    c: jchar    = u'\0'  # <-> unicode (one char)
    s: jshort   = 0      # <-> int
    i: jint     = 0      # <-> int
    j: jlong    = 0      # <-> int
    f: jfloat   = 0.0    # <-> float
    d: jdouble  = 0.0    # <-> float
    l: jobject  = None   # <->

jni.py nie pozwala na konwersje dla typow

    int    (jboolean)
    int    (jbyte)
    unicode(jchar)
    int    (jshort)
    int    (jint)
    long   (jlong)
    float  (jfloat)
    float  (jdouble)

-XX:+PrintJNIResolving
