java">public class Test1 {
int sum=0;
int a=1;
public void sum()
{
   sum+=a;
   a++;
   if(a<=1000)
   {
    sum();//调用自身实现递归
   }
}
public static void main(String[] args) {
   Test1 test=new Test1();
   test.sum();
   System.out.println("计算结果："+test.sum+"!");
}