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// This file illustrates the cross language polymorphism using directors.
// CEO class, which overrides Employee::getPosition().
class CEO extends Manager {
public CEO(String name) {
super(name);
}
public String getPosition() {
return "CEO";
}
// Public method to stop the SWIG proxy base class from thinking it owns the underlying C++ memory.
public void disownMemory() {
swigCMemOwn = false;
}
}
public class runme {
static {
try {
System.loadLibrary("example");
} 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[])
{
// Create an instance of CEO, a class derived from the Java proxy of the
// underlying C++ class. The calls to getName() and getPosition() are standard,
// the call to getTitle() uses the director wrappers to call CEO.getPosition().
CEO e = new CEO("Alice");
System.out.println( e.getName() + " is a " + e.getPosition() );
System.out.println( "Just call her \"" + e.getTitle() + "\"" );
System.out.println( "----------------------" );
// Create a new EmployeeList instance. This class does not have a C++
// director wrapper, but can be used freely with other classes that do.
EmployeeList list = new EmployeeList();
// EmployeeList owns its items, so we must surrender ownership of objects we add.
e.disownMemory();
list.addEmployee(e);
System.out.println( "----------------------" );
// Now we access the first four items in list (three are C++ objects that
// EmployeeList's constructor adds, the last is our CEO). The virtual
// methods of all these instances are treated the same. For items 0, 1, and
// 2, all methods resolve in C++. For item 3, our CEO, getTitle calls
// getPosition which resolves in Java. The call to getPosition is
// slightly different, however, because of the overridden getPosition() call, since
// now the object reference has been "laundered" by passing through
// EmployeeList as an Employee*. Previously, Java resolved the call
// immediately in CEO, but now Java thinks the object is an instance of
// class Employee. So the call passes through the
// Employee proxy class and on to the C wrappers and C++ director,
// eventually ending up back at the Java CEO implementation of getPosition().
// The call to getTitle() for item 3 runs the C++ Employee::getTitle()
// method, which in turn calls getPosition(). This virtual method call
// passes down through the C++ director class to the Java implementation
// in CEO. All this routing takes place transparently.
System.out.println( "(position, title) for items 0-3:" );
System.out.println( " " + list.get_item(0).getPosition() + ", \"" + list.get_item(0).getTitle() + "\"" );
System.out.println( " " + list.get_item(1).getPosition() + ", \"" + list.get_item(1).getTitle() + "\"" );
System.out.println( " " + list.get_item(2).getPosition() + ", \"" + list.get_item(2).getTitle() + "\"" );
System.out.println( " " + list.get_item(3).getPosition() + ", \"" + list.get_item(3).getTitle() + "\"" );
System.out.println( "----------------------" );
// Time to delete the EmployeeList, which will delete all the Employee*
// items it contains. The last item is our CEO, which gets destroyed as well.
list.delete();
System.out.println( "----------------------" );
// All done.
System.out.println( "java exit" );
}
}
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