采用递归就可以啦
import java.util.;
public class Main{
int n;
static int sum=0;
static int j=1;
static void f(int n) {
for(int i=1;i<=n;i++) {
j=i;
sum+=j;
}
System.out.println(sum);
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
f(n);
}
}