得到小于某一个数的所有素数

public class PrimeTest {
public static List<Integer> writePrimes(int n){
List<Integer> list = new ArrayList<Integer>();
for(int j=2;j<=n;j++){
list.add(new Integer(j));
}
for(int i=2;i*i<n;i++){
if(list.contains(new Integer(i))){
int m = 2*i;
while(m<=n){
list.remove(new Integer(m));
m+=i;
}
}
}
return list;
}
public static void main(String[] args) {
System.out.println(writePrimes(9));
}
}