Is the following valid if ShapeBase is defined as in listing 8.19? ShapeInterface shapeVariable = new ShapeBase(); Is the following valid if ShapeBase is defined as in listing 8.19, and Rectangle is...

Is the following valid if ShapeBase is defined as in listing 8.19?

ShapeInterface shapeVariable = new ShapeBase();

Is the following valid if ShapeBase is defined as in listing 8.19, and

Rectangle is as defined in listing 8.13 but ShapeBasics is replaced by

ShapeBase?

ShapeBase shapeVariable = new Rectangle();

WindowDestroyer in any standard Java package (library)?