[java] Display current time in 12 hour format with AM/PM

tl;dr

Let the modern java.time classes of JSR 310 automatically generate localized text, rather than hard-coding 12-hour clock and AM/PM.

LocalTime                                     // Represent a time-of-day, without date, without time zone or offset-from-UTC.
.now(                                         // Capture the current time-of-day as seen in a particular time zone.
    ZoneId.of( "Africa/Casablanca" )          
)                                             // Returns a `LocalTime` object.
.format(                                      // Generate text representing the value in our `LocalTime` object.
    DateTimeFormatter                         // Class responsible for generating text representing the value of a java.time object.
    .ofLocalizedTime(                         // Automatically localize the text being generated.
        FormatStyle.SHORT                     // Specify how long or abbreviated the generated text should be.
    )                                         // Returns a `DateTimeFormatter` object.
    .withLocale( Locale.US )                  // Specifies a particular locale for the `DateTimeFormatter` rather than rely on the JVM’s current default locale. Returns another separate `DateTimeFormatter` object rather than altering the first, per immutable objects pattern.
)                                             // Returns a `String` object.

10:31 AM

Automatically localize

Rather than insisting on 12-hour clock with AM/PM, you may want to let java.time automatically localize for you. Call DateTimeFormatter.ofLocalizedTime.

To localize, specify:

  • FormatStyle to determine how long or abbreviated should the string be.
  • Locale to determine:
    • The human language for translation of name of day, name of month, and such.
    • The cultural norms deciding issues of abbreviation, capitalization, punctuation, separators, and such.

Here we get the current time-of-day as seen in a particular time zone. Then we generate text to represent that time. We localize to French language in Canada culture, then English language in US culture.

ZoneId z = ZoneId.of( "Asia/Tokyo" ) ;
LocalTime localTime = LocalTime.now( z ) ;

// Québec
Locale locale_fr_CA = Locale.CANADA_FRENCH ;  // Or `Locale.US`, and so on.
DateTimeFormatter formatterQuébec = DateTimeFormatter.ofLocalizedTime( FormatStyle.SHORT ).withLocale( locale_fr_CA ) ;
String outputQuébec = localTime.format( formatterQuébec ) ;

System.out.println( outputQuébec ) ;

// US
Locale locale_en_US = Locale.US ;  
DateTimeFormatter formatterUS = DateTimeFormatter.ofLocalizedTime( FormatStyle.SHORT ).withLocale( locale_en_US ) ;
String outputUS = localTime.format( formatterUS ) ;

System.out.println( outputUS ) ;

See this code run live at IdeOne.com.

10 h 31

10:31 AM