code: public static StackTraceElement getStackTraceElement(int i) {
  		StackTraceElement[] stackTrace = getStackTrace();
  		if (i < 0) {
  			i += stackTrace.length;
  		}
  		return stackTrace[i];
  	}
docs: 获得堆栈项
  
  @param i 第几个堆栈项
  @return 堆栈项