题目：判断一个数是否是2的方次幂

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");    }    }