Java中日期的加减 [英] Addition and Subtraction of Dates in Java

问题描述

如何在java中添加或减去日期？例如 java.sql.Date 并格式如下： yyyy-MM-dd ，我该如何添加5个月？我在一些教程中看到他们使用 Calendar ，我们可以设置日期吗？请帮助。

How can we add or subtract date in java? For instance java.sql.Date and formatted like this: yyyy-MM-dd, how can i Add 5 months from that? I've seen in some tutorial that they are using Calendar, can we set date on it? Please Help.

示例： 2012-01-01 添加5个月后将成为 2012-06-01 。

Example: 2012-01-01 when added 5 months will become 2012-06-01.

PS：我是一个.NET程序员，慢慢学习Java环境。 >

PS: I'm a .Net Programmer and slowly learning to Java environment.

推荐答案

首先，您必须将 String date转换为 java.util.Date ，比您必须使用 java.util.Calendar 来处理日期。也可以用millis来做数学，但是我不推荐这个。

First of all you have to convert your String date to java.util.Date, than you have to use java.util.Calendar to manipulate dates. It is also possible to do math with millis, but I do not recommend this.

public static void main( final String[] args ) throws ParseException {
    final String sdate = "2012-01-01";
    final SimpleDateFormat df = new SimpleDateFormat( "yyyy-MM-dd" );
    final Date date = df.parse( sdate ); // conversion from String
    final java.util.Calendar cal = GregorianCalendar.getInstance();
    cal.setTime( date );
    cal.add( GregorianCalendar.MONTH, 5 ); // date manipulation
    System.out.println( "result: " + df.format( cal.getTime() ) ); // conversion to String
}

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