Java计算程序运行时间

public static void main(String[] args) {
		// TODO Auto-generated method stub
		long nd = 1000 * 24 * 60 * 60;
		long nh = 1000 * 60 * 60;
		long nm = 1000 * 60;
		long ns = 1000;
		// 获得两个时间的毫秒时间差异
		System.out.println("开始运行");
		Date nowDate = new Date();
		new Subgraph_processed03().subgraphProcess();
		// System.out.println("已完成");
		Date endDate = new Date();
		long diff = endDate.getTime() - nowDate.getTime();//getTime返回的是一个long型的毫秒数
		// 计算差多少天
		long day = diff / nd;
		// 计算差多少小时
		long hour = diff % nd / nh;
		// 计算差多少分钟
		long min = diff % nd % nh / nm;
		// 计算差多少秒//输出结果
		long sec = diff % nd % nh % nm / ns;
		//计算多少毫秒
		long ms=diff% nd % nh % nm % ns;
		System.out.println(day + "天" + hour + "小时" + min + "分钟"+sec+"秒"+ms+"毫秒");
	}