Java Basics-Date formatting DateFormat class Introduction

Java Basics-Date formatting DateFormat class Introduction

Yun Zhengjie

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I. Overview of the DateFormat class

DateFormat is an abstract class of date/time formatting subclasses (descriptions cannot be instantiated directly), and it formats and resolves dates or times in a language-independent manner. Date/time formatting subclasses (such as SimpleDateFormat) allow formatting (that is, date-and text), parsing (text-to-date), and normalization. Represents a date as an Date object, or as the number of milliseconds from GMT (Greenwich Mean Time) January 1, 1970 00:00:00 This moment.

two. SimpleDateFormat class overview

　　SimpleDateFormat is a specific class that formats and resolves dates in a language-related way. It allows formatting (date-and text), parsing (text-to-date), and normalization.

Three. How to format dates

1> Create SimpleDateFormat Object

In the class construction method, the string is written in many date formats, and the format can be customized, but the following rules are required:

2>. SimpleDateFormat to format dates by calling format

1  PackageCn.org.yinzhengjie.Demo;2 3 ImportJava.text.SimpleDateFormat;4 Importjava.util.Date;5 6  Public classSimpledateformatdemo {7 8      Public Static voidMain (string[] args) {9SimpleDateFormat SDF =NewSimpleDateFormat ("yyyy mm month DD Day HH point mm minutes ss seconds! ");TenString date = Sdf.format (NewDate ()); One System.out.println (date); A  -     } -  the } -  -  - /* + The result of the above code execution is as follows: - April 18, 2018 17 O ' 01分钟16秒!  + */

Four. String converted to date object

1> Create a SimpleDateFormat object

In the construction method, specify the date format.

2>. Subclass object, calling method parse, passing string, returns date.

1  PackageCn.org.yinzhengjie.Demo;2 3 Importjava.text.ParseException;4 ImportJava.text.SimpleDateFormat;5 Importjava.util.Date;6 7  Public classSimpledateformatdemo {8 9      Public Static voidMain (string[] args)throwsParseException {Ten         //incoming parameters require a custom format OneSimpleDateFormat SDF =NewSimpleDateFormat ("Yyyy-mm-dd"); A         //the incoming format needs to be consistent with the format you define, otherwise it will be an error! You need to handle exceptions when calling the Parse method.  -Date date = Sdf.parse ("1990-05-19"); - System.out.println (date); the     } -  - } -  +  - /* + The result of the above code execution is as follows: A Sat may 00:00:00 gmt+08:00 1990 at */

Java Basics-Date formatting DateFormat class Introduction