1.Date类的构造方法
Date是表示时间的类
空参构造
public Date()
public class Demo {
public static void main(String[] args) {
Date date = new Date();
System.out.println(date);
}
}
带参构造
public Date(long times)
public static void main(String[] args) {
Date date = new Date(30000);
System.out.println(date);
}
2.Date类的get和set方法
public long getTime()
将当前的日期对象，转为对应的毫秒值
public static void main(String[] args) {
Date date = new Date();
System.out.println(date);
long time = date.getTime();
System.out.println(time);
}
public void setTime(long times);
根据给定的毫秒值，生成对应的日期对象
public static void main(String[] args) {
Date date = new Date();
System.out.println(date);
date.setTime(30000);
System.out.println(date);
}
3.日期格式化SimpleDateFormat
public static void main(String[] args) {
SimpleDateFormat s1 = new SimpleDateFormat();
String sd = s1.format(new Date());
System.out.println(sd);
}
public static void main(String[] args) {
SimpleDateFormat s1 = new SimpleDateFormat("yyyy-MM-dd");
String sd = s1.format(new Date());
System.out.println(sd);
}
4.DateFormat类
parse 将字符串 解析为 日期的对象,即从1970年到输入的年与日的毫秒数
public static void main(String[] args) throws ParseException {
SimpleDateFormat s1 = new SimpleDateFormat("yyyy-MM-dd");
Date date = s1.parse("1993-6-23");
long time = date.getTime();
System.out.println(time);
}
5 Calendar类
Calendar 类是一个抽象类，所以不能直接new一个对象出来
get()方法：获得当前日历的年月日
public static void main(String[] args) {
Calendar c = Calendar.getInstance(); //不能直接new
int year = c.get(Calendar.YEAR); //用Calendar.YEAR方法获得年
int month = c.get(Calendar.MONTH)+1; //月份是从0开始计算的
int day = c.get(Calendar.DAY_OF_MONTH); //获得日
System.out.println(year);
System.out.println(month);
System.out.println(day);
}
set(int field,int value)方法：设置日历
public static void main(String[] args) {
Calendar c = Calendar.getInstance();
c.set(2022, 4, 23);
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH); //注意此处不加1
int day = c.get(Calendar.DAY_OF_MONTH);
System.out.println(year);
System.out.println(month);
System.out.println(day);
}
add 日历偏移量
public static void main(String[] args) {
Calendar c = Calendar.getInstance();
c.add(Calendar.DAY_OF_MONTH, 30); //往后增加30天
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH)+1;
int day = c.get(Calendar.DAY_OF_MONTH);
System.out.println(year);
System.out.println(month);
System.out.println(day);
}
原文：https://www.cnblogs.com/smxbo/p/10666594.html