Re: Accessing static members with J/Link

*To*: mathgroup at smc.vnet.net*Subject*: [mg110994] Re: Accessing static members with J/Link*From*: John_V <jvillar.john at gmail.com>*Date*: Fri, 16 Jul 2010 05:17:14 -0400 (EDT)

Well, problem solved. I'm answering my own post in case others have been confused as I was. As I discovered on my own after posting Needs["JLink`"] InstallJava[] myMathClass = LoadJavaClass["java.lang.Math"] pi = java`lang`Math`PI java`lang`Math`abs[-5] works. An e-mail from Wolfram told me I can also use the shorter form pi = Math`PI Math`abs[-5] The key (and my point of confusion) is that the short form uses the Java class name, *not* the object returned by LoadJavaClass["..."] John On 7/15/2010 3:09 AM, John_V wrote: > I'm trying to learn how to use J/Link, and I have run into an elementary > (I hope) problem when I try to access static methods and fields. For > example, the Java Math class has static fields for E and PI and a number > of static methods, abs() among them. Here's what happens when I try to > use them: > > My inputs: > > Needs["JLink`"] > InstallJava[] > myMathClass = LoadJavaClass["java.lang.Math"] > Fields[myMathClass] > pi = myMathClass`PI > myMathClass`abs[-5] > > /Mathematica/'s outputs: > > Out[2]= LinkObject[...] > > Out[3]= JavaClass[java.lang.Math,<> ] > > Out[4]//TableForm= > static final double E > static final double PI > > Out[5]= myMathClass`PI > > Out[6]= myMathClass`abs[-5] > > I believe the fact that Out[4] correctly lists java.lang.Math's static > fields means LoadJavaClass worked, but I expected Out[5] = 3.1415... and > Out[6] = 5. I thought this was a near verbatim transcription of the > examples in the "Calling Methods and Accessing Fields" part of the > J/Link user guide. What am I doing wrong? > > Thanks, > > John > >