Hi,
Using java-1.2.6, I have a problem with passing a Boolean parameter to a Java
method.
It seems that octave logical type is translated into java.lang.Double, not
java.lang.Boolean.
At least in some cases.
Here is the method I want to call (from Weka 3.6.2):
public double[] evaluateModel(Classifier classifier,
Instances data,
java.lang.Object... forPredictionsPrinting)
throws java.lang.Exception
Calling
> java_invoke(o, "evaluateModel", c, d)
I get this error:
error: [java] java.lang.NoSuchMethodException: evaluateModel
So, I need to provide the optional parameter "forPredictionsPrinting".
If provided, forPredictionsPrinting needs to be a StringBuffer object, a
weka.core.Range object, and a boolean:
sf = java_new('java.lang.StringBuffer');
range = java_new('weka.core.Range','first-last');
jtrue = java_new('java.lang.Boolean', true);
Still,
> java_invoke(o, 'evaluateModel', c, d, sf,range,jtrue);
produces
error: [java] java.lang.NoSuchMethodException: evaluateModel
I need to put the optional parameters into a Java array:
jarray = java_new('java.lang.Object',3);
jarray(1) = sf;
jarray(2) = range;
jarray(3) = jtrue;
Calling
> java_invoke(o, 'evaluateModel', c, d, jarray)
I now get the following error:
error: [java] java.lang.ClassCastException: java.lang.Double cannot be
cast to java.lang.Boolean
In fact, evaluateModel casts forPredictionsPrinting[2] to
java.lang.Boolean, but the parameter has been converted into a
java.lang.Double.
With jarray(3) = logical(1), I get the same error.
The only solution I've found was to remove lines 762 to 770 in
__java__.cc:
if (retval.is_undefined ())
{
cls = jni_env->FindClass ("java/lang/Boolean");
if (jni_env->IsInstanceOf (jobj, cls))
{
jmethodID m = jni_env->GetMethodID (cls, "booleanValue",
"()Z");
retval = jni_env->CallBooleanMethod (jobj, m);
}
}
Doing this, jtrue remains a Java object instead of being converted into
an Octave double.
Like this, calling
> java_invoke(o, 'evaluateModel', c, d, jarray)
works fine.
Is there any possibility to solve this in a better way?
I think, octave logical type should always be converted into
java.lang.Boolean and vice versa.
Thanks,
Gerhard
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