Static referencing of classes and functions in library

Prokop Ha..

Static referencing of classes and functions in library

in Library and Tool Development • 2 years ago

Hello,

I just managed to compile procesing library template in Eclipse, and I'm trying to move some N-dimensional vector operations to this library. I'm not very familier with pure java or eclipse (just with C and Fortran), so I'm a bit confused about thinks like static, final, abstract, interface .... and that everything in java must be inside class.

My problem:

I would like to reference function from my library without creating an instance of the class.

for example I have this simple library in Eclipse:

package template.library
import processing.core.*;
import java.lang.Math;
public class HelloLibrary {
public final double rndBell(){
double a = Math.random();
double b = Math.random();
double c = Math.random();
double r = (a+b+c)*0.33333333 -1.0;
return r;
}
}

I would like to call rndBell() in processing like this:

import template.library.Hellolibrary.*;
println( rndBell() );

But to do this it would be necessary (probably) to make HelloLibrary static (?) which Eclipse says is not possible (why?)

so I need before calling rndBell create instance of the class ( which I don't wan't ) like this:

import template.library.*;
HelloLibrary hello = new HelloLibrary(this);
println(hello.rndBell());

=======================================================

an other problem is that eclipse template there are set some paths:

classpath.local C:\Documents and Settings\asiJa/Documents/workspace/libs
sketchbook C:\Documents and Settings\asiJa/Documents/Processing

which I don't know how to change to correct (I tried to search for string classpath.local but found no definition )

classpath.local C:\Documents and Settings\asiJa\workspace\libs
sketchbook C:\Documents and Settings\asiJa/Plocha/Processing

But it's not a big issue, I just must copy compiled library always to the correct location

Replies(2)

PhiLho

Re: Static referencing of classes and functions in library

2 years ago

OK, I suggest to find a better package name and a better class name, but that's cosmetic...

I haven't used the template for libraries, so I can't comment much there. But I think I can help with Java.
You don't declare the class as static (that's only for internal classes), but you can declare the method itself static, which allows you do call it with HelloWorld.rndBell()

quarks

Re: Static referencing of classes and functions in library

2 years ago

The classpath variables are defined in the build.properties file in the resources folder in the Eclipse project - you need to modify them to suit your own directory structure.

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