在用户在JDateChooser中选择出生日期之后，在文本字段中显示年龄 [英] To display age in textfield after user has selected date of birth in JDateChooser

问题描述

我的程序中有一个JDateChooser.每当从JDateChooser中选择他的出生日期时，我都希望他的年龄显示在JTextField中.

I have a JDateChooser in my program. Whenever the selects his date of birth from JDateChooser , I want his age to be displayed in a JTextField.

最初，我尝试使它与MouseListener一起使用:

Initially, I tried to make it work with the MouseListener as :

private void jDateChooser1MouseExited(java.awt.event.MouseEvent evt) 
{                                                
  Calendar dob = Calendar.getInstance();  

 //utilDob is a java.util.Date variable which stores date selected by user
 dob.setTime(utilDob);  
 Calendar today = Calendar.getInstance();  
 int age = today.get(Calendar.YEAR) - dob.get(Calendar.YEAR);  
 if (today.get(Calendar.MONTH) < dob.get(Calendar.MONTH))
   age--;  
 else if (today.get(Calendar.MONTH) == dob.get(Calendar.MONTH)
                                && today.get(Calendar.DAY_OF_MONTH) <    dob.get(Calendar.DAY_OF_MONTH)) 
     age--;  


 jTextField11.setText(Integer.toString(age));
 displayAge=Integer.parseInt(jTextField11.getText());
}                               

但是，上述功能对我没有帮助.我还可以使用其他事件/动作侦听器吗?

But, the above mentioned function didn't help me. Is there any other event/action listener I can use?

推荐答案

您正在使用过时的类.

You are using outmoded classes.

Java 8和更高版本内置了java.time框架.

Java 8 and later comes with the java.time framework built-in.

LocalDate 类表示仅日期的值，没有日期和时区.但是时区对于确定今天"至关重要.在任何给定时刻，日期可能会在世界各地随时区变化.巴黎午夜过后的片刻仍是蒙特利尔的昨天".

The LocalDate class represents a date-only value, without time-of-day and without time zone. But time zone is critical it determining "today". For any given moment the date may vary around the world by time zone. A few moments after midnight in Paris is still "yesterday" in Montréal.

ZoneId zoneId = ZoneId.of ( "America/Montreal" );
LocalDate today = LocalDate.now ( zoneId );

根据您的用户输入来建立出生日期.

Build a date-of-birth from your user input.

LocalDate dob = LocalDate.of ( 1955 , 1 , 2 );

或解析符合 ISO 8601 标准的字符串.

Or parse a string compliant with the ISO 8601 standard.

LocalDate dob = LocalDate.parse( "1955-01-02" );

或使用DateTimeFormatter来帮助解析其他字符串.

Or use a DateTimeFormatter to help parse a different string.

如果手头有java.util.Date对象，请使用添加到该旧类中的新方法来转换为java.time:java.util.Date::toInstant. Instant是UTC时间轴上的时刻.

If you have a java.util.Date object on hand use a new method added to that old class for conversion to java.time: java.util.Date::toInstant. An Instant is a moment on the timeline in UTC.

Instant instant = myJavaUtilDate.toInstant();

苹果公司所在的时区.

Apple a time zone.

ZoneId zoneId = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId );

提取一个LocalDate.

LocalDate localDate = zdt.toLocalDate();

Period

年龄只是一种消逝的时间，是一段时间.在java.time中，Period类表示以年，月和日为单位的时间跨度.

Period

Age is just one kind of elapsed time, a span of time. In java.time, the Period class represents a span of time tracked in terms of years, months, and days.

Period age = Period.between ( dob , today );

从Period

获取年份

如果您想要的话，请询问年份.

Get years from Period

Ask for the years if that is all you want.

int years = age.getYears ();

请注意，您可能会认为getYears不是 归一化为全部年数.根据Period的构造方式，您可能会得到意想不到的结果.另一种方法是调用toTotalMonths()并除以12(十二个月到一年).在此快速示例中，请参见两种方法.比较y和y2.

Beware that getYears is not normalized to the full number of years as you may intuit. Depending on how a Period is constructed, you may get an unexpected result. Another approach is to call toTotalMonths() and divide by 12 (twelve months to a year). See both approaches in this quick example; compare y and y2.

Period p = Period.ofMonths ( 25 );
int y = p.getYears ();
long y2 = ( ( p.toTotalMonths () ) / 12 );
System.out.println ( "p: " + p + " | y: " + y + " | y2: " + y2 );

p:P25M | y:0 | y2:2

p: P25M | y: 0 | y2: 2

更好的是，强制将Period对象规范化为完整的年份，然后是几个月，然后是几天.好吧，不是完全强制对象:由于不可变对象，您实际上是在实例化一个基于原始对象的值.

Even better, force the Period object to be normalized to a full count of years then months then days. Well, not exactly force the object: Because of immutable objects, you are actually instantiating a new object based on the original object’s values.

因此，尽管我们的age对象由于其特殊的构造而已经被规范化，但总是调用normalized可能是一个好习惯.

So while our age object happens to already be normalized because of its particular construction, it might be a good habit to always call normalized.

Period age = Period.between ( dob , today ).normalized();

转储到控制台.默认情况下，Period::toString方法根据持续时间的ISO 8601标准生成字符串.例如在这里看到的P61Y2M27D.

Dump to console. By default, the Period::toString method generates a string according to the ISO 8601 standard for Durations such as P61Y2M27D seen here.

System.out.println ( "zoneid: " + zoneId + " | today: " + today + " | dob: " + dob + " | age: " + age + " | years: " + years );

zoneid:美国/蒙特利尔|今天:2016-03-29 | dob:1955-01-02 |年龄:P61Y2M27D |年:61

zoneid: America/Montreal | today: 2016-03-29 | dob: 1955-01-02 | age: P61Y2M27D | years: 61

将int转换为Integer

最后，如果您需要一个对象而不是原始对象，请将int转换为Integer.

Convert int to Integer

Lastly, if you need an object rather than a primitive, convert int to Integer.

Integer yearsObj = Integer.valueOf(years);

Integer yearsObj = Integer.valueOf ( years );

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