个人总结

No.1-----------------------------------

 class Demo{
 public static void main(String args[]){
  int a = 3;
  int y;
  y = 3<<a;
  System.out.println (y); 
 } 
}

     向左位移a就代表乘以2的a次方，向右位移a就代表除以2的a次方
     y = 3<<a  ===   y = 3 * 2³
     y = 3>>a  ===   y = 3 / 2³

      ^{public  Integer.toHexString(int i){}    return (base 16)}