java中Parallelogramp=(Parallelogram)q第二个Parallelogram括起来代表什么.classQuadrangle{\x05publicstaticvoiddraw(Quadrangleq){\x05\x05//SomeSentence\x05}}classSquareextendsQuadrangle{\x05//SomeSentence}classAnything{\x05

Question

java中Parallelogram p = (Parallelogram) q 第二个Parallelogram括起来代表什么.
class Quadrangle {
\x05public static void draw(Quadrangle q) {
\x05\x05// SomeSentence
\x05}
}
class Square extends Quadrangle {
\x05// SomeSentence
}
class Anything {
\x05// SomeSentence
}
public class Parallelogram extends Quadrangle {
\x05public static void main(String args[]) {
\x05\x05Quadrangle q = new Square(); // 实例化父类对象
\x05\x05// 判断父类对象是否为Parallelogram子类的一个实例
\x05\x05if (q instanceof Parallelogram) {
\x05\x05\x05System.out.println("123");
\x05\x05Parallelogram p = (Parallelogram) q; // 向下转型操作
\x05\x05}
\x05\x05// 判断父类对象是否为Parallelogram子类的一个实例
\x05\x05if (q instanceof Square) {
\x05\x05\x05System.out.println("123456");
\x05\x05\x05Square s = (Square) q; // 进行向下转型操作
\x05\x05}
\x05\x05// 由于q对象不为Anything类的对象,所以这条语句是错误的
\x05\x05// System.out.println(q instanceof Anything);
\x05}
}
其中的Parallelogram p = (Parallelogram) q和Square s = (Square) q 是怎么赋值的?

Answer 1

强制转换为Parallelogram类