用java判断一个数是否为素数

public class Num{
public static void main(String args[]){
int m;
boolean tag=true;
System.out.print("Please enter a num:");
try{
m=(int)System.in.read();
for(int i=m-1;i>1;i--)
if(m%i==0)
tag=false;
if(tag==true)
System.out.println(m+"is a sushu");
}catch(IOExceptimn e){}
}
}

public class Prime {

public static Boolean Prime(int n) {
for (int i = 2; i < Math.sqrt(n); i++) {
if (n % i == 0)
return false;
}
return true;
}

public static void main(String[] args) {

int i = 8;
Prime prime = new Prime();
if (Prime(i))
System.out.println(i + " is a prime");
else
System.out.println(i + " is not a prime");
}
}
楼主试一下··

解这个问题比较流行用完全平方法