// file: main.java // This file illustrates the manipulation of C++ references in Java. import example; public class main { 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[]) { System.out.println( "Creating some objects:" ); Vector a = new Vector(3,4,5); Vector b = new Vector(10,11,12); System.out.println( " Created " + a.print() ); System.out.println( " Created " + b.print() ); // ----- Call an overloaded operator ----- // This calls the wrapper we placed around // // operator+(const Vector &a, const Vector &) // // It returns a new allocated object. System.out.println( "Adding a+b" ); Vector c = new Vector (example.addv(a.getCPtr(),b.getCPtr()), false); System.out.println( " a+b = " + c.print() ); // Note: Unless we free the result, a memory leak will occur // This is because we used 'false' for cMemoryOwn in the constructor of c. // If we had used 'true', the memory management is best left to the garbage collector. // You can still call _delete(). It will free the c++ memory immediately, but not the // Java memory! You then must be careful not to call any member functions as it will // use a NULL c pointer on the underlying c++ object. c._delete(); // ----- Create a vector array ----- // Note: Using the high-level interface here System.out.println( "Creating an array of vectors" ); VectorArray va = new VectorArray(10); System.out.println( " va = " + va.toString() ); // ----- Set some values in the array ----- // These operators copy the value of Vector a and Vector b to the vector array va.set(0,a); va.set(1,b); // This will work, but it will cause a memory leak! // This is the low level way of using Java with SWIG and isn't very readable! example.VectorArray_set(va.getCPtr(),2,example.addv(a.getCPtr(),b.getCPtr())); // The non-leaky way to do it. This is the high level way of using Java with SWIG. // This relies on the garbage collector for freeing memory // An even better way would have been possible if addv was a static function in the // c++ class. The code would then instead be: // c = Vector.addv(a,b); c = new Vector(example.addv(a.getCPtr(),b.getCPtr()), true); va.set(3,c); // Get some values from the array System.out.println( "Getting some array values" ); for (int i=0; i<5; i++) System.out.println( " va(" + i + ") = " + va.get(i).print() ); // Watch under resource meter to check on this System.out.println( "Making sure we don't leak memory." ); for (int i=0; i<1000000; i++) c = va.get(i%10); // ----- Clean up ----- // This could be omitted. The garbage collector would then clean up for us. System.out.println( "Cleaning up" ); va._delete(); a._delete(); b._delete(); } }