| // 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" ); |
| |
| } |
| } |