java yyyy-mm-dd 日期格式_Java中的日历日期为yyyy-MM-dd格式

How to convert calendar date to yyyy-MM-dd format.

Calendar cal = Calendar.getInstance();

cal.add(Calendar.DATE, 1);

Date date = cal.getTime();

SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");

String date1 = format1.format(date);

Date inActiveDate = null;

try {

inActiveDate = format1.parse(date1);

} catch (ParseException e1) {

// TODO Auto-generated catch block

e1.printStackTrace();

}

This will produce inActiveDate = Wed Sep 26 00:00:00 IST 2012. But what I need is 2012-09-26. My purpose is to compare this date with another date in my database using Hibernate criteria. So I need the date object in yyyy-MM-dd format.

最佳答案

A Java Date is a container for the number of milliseconds since January 1, 1970, 00:00:00 GMT.

When you use something like System.out.println(date), Java uses Date.toString() to print the contents.

The only way to change it is to override Date and provide your own implementation of Date.toString(). Now before you fire up your IDE and try this, I wouldn't; it will only complicate matters. You are better off formatting the date to the format you want to use (or display).

Java 8+

LocalDateTime ldt = LocalDateTime.now().plusDays(1);

DateTimeFormatter formmat1 = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.ENGLISH);

System.out.println(ldt);

// Output "2018-05-12T17:21:53.658"

String formatter = formmat1.format(ldt);

System.out.println(formatter);

// 2018-05-12

Java 8之前的版本

您应该利用ThreeTen Backport

以下内容出于历史目的保留(作为原始答案)

您可以做的是格式化日期。

Calendar cal = Calendar.getInstance();

cal.add(Calendar.DATE, 1);

SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");

System.out.println(cal.getTime());

// Output "Wed Sep 26 14:23:28 EST 2012"

String formatted = format1.format(cal.getTime());

System.out.println(formatted);

// Output "2012-09-26"

System.out.println(format1.parse(formatted));

// Output "Wed Sep 26 00:00:00 EST 2012"

这些实际上是同一日期，表示方式有所不同。