swig/Examples/test-suite/java/virtual_poly_runme.java

// virtual_poly test

import virtual_poly.*;

public class virtual_poly_runme {

  static {
    try {
	System.loadLibrary("virtual_poly");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[]) {

    NDouble d = new NDouble(3.5);
    NInt i = new NInt(2);

    NInt j = virtual_poly.incr(i);
    //
    // These two natural 'copy' forms fail, only java and csharp
    // because no polymorphic return types are supported. 
    // But we can live with this restriction, more or less.
    //
    // NDouble dc = d.copy();
    // NInt ic = i.copy();

    //
    // These two 'copy' forms work, but we end  with plain NNumbers
    //
    NNumber dc = d.copy();
    NNumber ic = i.copy();


    //
    // The real problem is that there is no way to recover the
    // original NInt or NDouble objects, even when you try to use the
    // plain and natural C++ dynamic_cast operation, or the user
    // downcasting mechanism:
    //

    // don't work
    NDouble ddc = NDouble.narrow(dc);
    NInt dic = NInt.narrow(ic);
  }
}