Re: [Jython-users] Strange behavior of Integer and Double

[<bc...@wo...>]

[Will]

>I have run into some surprising behavior of Java Integer objects while using
>jython:
>
>public class Test {
>
>	public void foo(Integer I) {
>		System.out.println("Called with an Integer.");
>	}
>
>  	public void foo(int i) {
> 		System.out.println("Called with an int.");
>  	}
>
>	public static void main(String[] args) {
>
>		... initialize PythonInterpreter ...
>
>		myInterpreter.exec("test = Test()");
>		myInterpreter.exec("test.foo(Integer(1))");
>		myInterpreter.exec("test.foo(2)");
>	}
> }
>
>
>Expected output:
>	Called with an Integer.
>	Called with an int.
>
>Actual output:
>	Called with an int.
>	Called with an int.
>
>
>I have noticed similar behavior with Double objects.
>
>What am I doing wrong?  How can I keep Integer and Double objects from being
>converted to Java primitives?

You can't. The eagerness with which Jython converts the java.lang.*
wrapper classes to instances of native python classes have been
discussed previousely:

http://mail.python.org/pipermail/jpython-interest/1999-December/002590.html

It is basicly the same problem you have re-discovered. I'm still not
convinved that it is a net win to reduce this eagerness.

http://mail.python.org/pipermail/jpython-interest/1999-December/002596.html


>Also, why does the following call to equals() on an Integer object...
>
>	myInterpreter.set("myInteger", new Integer(1));
>	myInterpreter.exec("myInteger.equals(Integer(1))");
>
>...result in an exception?
>
>	Exception in thread "main" Traceback (innermost last):
>	  File "<string>", line 1, in ?
>	AttributeError: 'int' object has no attribute 'equals'

Use this instead:

	myInterpreter.set("myInteger", 
			new PyJavaInstance(new Integer(1)));
	myInterpreter.exec("myInteger.equals(Integer(1))");


regards,
finn