public class Power {

    public static void main(String [] args) throws NumberFormatException, IOException{

        System.out.println("请输入一个数：");

        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

        int i=Integer.parseInt(br.readLine());

        isPower(i);

    }

private static void isPower(int num){

    if(((num - 1) & num) == 0){

        System.out.println("是方次幂");

    }else{

        System.out.println("不是方次幂");

    }

　}

}

private static void isPower(int num){

    boolean flag=false;

    for(int i=num;i>0;i--){

        int a = num/2;

        int b=num%2;

        num=a;

        System.out.println("num是"+num+"取余是"+b);

            if(num>2){

                System.out.println(88);

            }

            if(num<=2){

            int c=(num*2+b)%2;

                if(c==0){

                    flag=true;

                }else{

                    flag=false;

                }

            break;

        }

    }

    if(flag==true){

        System.out.println("该数是2的方次幂");

    }

    if(flag==false){

        System.out.println("该数不是2的方次幂");

    }

}