import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public int Sum(int n) {
        int sum = 0;
        for (int i = 0; i < n + 1; i++) {
            sum = sum + i;
        }
        return sum;
    }
    public static void main(String[] args) {
        Main problem = new Main();
        int a[] = new int[100], m = 0, i = 0;
        String strInt = null;
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                System.in));
        while (true) {
            try {
                strInt = reader.readLine();
                if (strInt.matches("^[1-9][0-9]+$")) {//不退出怎么行。这样的结果你满意吗？
                    a[i++] = Integer.parseInt(strInt);
                    break;
                } else {
                    System.out.println("输入数据无效，请重新输入");
                }
            } catch (NumberFormatException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        while (a[m] != 0) {
            System.out.println(problem.Sum(a[m++]));
            System.out.print("\n");
        }
    }
}
运行结果：
100
5050

------解决方案--------------------
好难哦

------解决方案--------------------
那楼主还有啥问题啊，感觉没什么问题了，多加点约束条件撒