instanceof操作符判断对象类型

　　instanceof 的语法格式如下：

myobject instanceof ExampleClass

myobject：某类的对象引用

ExampleClass：某个类

 1 class Quadrangle{
 2     public static void draw(Quadrangle q) {
 3     }
 4 }
 5 
 6 class Square extends Quadrangle {
 7     
 8 }
 9 
10 class Anything {
11     
12 }
13 public class Parallelogram extends Quadrangle {
14 
15     public static void main(String[] args) {
16 
17         Quadrangle q = new Quadrangle();
18         //判断父类对象是否为Parallelogram子类的一个实例
19         if(q instanceof Parallelogram) {
20             Parallelogram p = (Parallelogram) q;
21         }
22         if(q instanceof Square){
23             Square s = (Square)q;
24         }
25     }
26 
27 }