文章目录

Date()

public Date()分配 Date 对象并初始化此对象，以表示分配它的时间（精确到毫秒）。

SimpleDateFormat()

例子1：

package cn.edut.tarena.demo1;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.junit.Test;

public class Demo_Date {
	@Test
	public void test001() {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		String date = "2019-11-12";
		Date d = null;
		try {
			d = sdf.parse(date) ;
		} catch (ParseException e) {
			e.printStackTrace();
		}
		System.out.println(d.toLocaleString());
	}
}

例子2：计算间隔天数

/** * 计算存活天数 */
	@Test
	public void test002() {
		String birthday = "2018-11-11";
		System.out.println(birthday);
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		long millionSecond = -1;
		try {
			millionSecond = countMillionSecondToNow(sdf.parse(birthday));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		System.out.println("已存活millionSecond："+millionSecond);
		System.out.println("已存活天数："+millionSecond/(1000*60*60*24));
	}
	
	public long countMillionSecondToNow(Date startDate) {
		return System.currentTimeMillis()-startDate.getTime();
	}