instanceof操作符判断对象类型

class Quadrangle{
public static void draw(Quadrangle q) {
}
}

class Square extends Quadrangle {

}

class Anything {

}
public class Parallelogram extends Quadrangle {

public static void main(String[] args) {

Quadrangle q = new Quadrangle();
//判断父类对象是否为Parallelogram子类的一个实例
if(q instanceof Parallelogram) {
Parallelogram p = (Parallelogram) q;
}
if(q instanceof Square){
Square s = (Square)q;
}
}

}