public static String getStackTrace() {
		String s = "";
		StackTraceElement[] list = Thread.currentThread().getStackTrace();
		if(list.length <= 2) {
			return ""; // no stack trace
		}
		for(int i=2; true; i++) {
			s += list[i].toString();
			if(i >= list.length - 1) {
				break;
			}
			s += "\n";
		}
		return s;
	}