获得任意时间的下一天时间

import java.util.Calendar;
import java.util.Date;
public class NextDay {
	public static void main(String[] args) {
		//Calendar为抽象类，没有构造方法，使用静态方法getInstance()进行实例化
		Calendar now = Calendar.getInstance();
		//或Date now = new Date();
		System.out.println(getNextDay(now));
	}
	private static Date getNextDay(Calendar now) {
		Date dateNow = now.getTime(); //将Calendar类转换为Date类
		long base = 1;
		//用毫秒构造新的日期其中1为之后的一天
		long addTime = base * 1 * 24 * 60 * 60 * 1000;
		Date date = new Date(dateNow.getTime() + addTime);
		//或 Date date = new Date(now.getTime().getTime() + addTime);
		return date;
	}
}

注意：Calendar和Date类都有getTime()方法，但意义不同，
1.Object Calendar.getTime()：Returns a Date object representing this Calendar’s time value (millisecond offset from the Epoch”).
2.Date Date.getTime()：Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object.