How to check number prime or not in java

primeno.java

class primeno
{
public static void main(String args[])
{
int no=17,flag=0;
int m=no/2;

for(int i=2;i<=m;i++)
{
if(no%i==0)
{
System.out.println("This Number is not Prime");
flag=1;
break;
}

}
if(flag==0)
{
System.out.println("This number is Prime");
}
}
}