4. Dates, Times, Locales and Resource bundles Flashcards
How are the classes in java.time organised?
- Local dates and times: these dates are local to your time zone, the classes: LocalDate, LocalTime, LocalDateTime
- Zoned dates and times: these dates include time-zone information, the classes:
ZonedDateTime and OffsetDateTime - Formatters for dates and times: you can parse dates with patterns and in a variety of styles,
the classes: format.DateTimeFormatter - Adjustments to dates and times: you can adjust and manipulate dates and times by handy
increments, the classes: temporal.TemporalAdjusters and temporal.ChronoUnit - Periods, Durations: represent an amount of time, periods for days or longer and durations
for shorter periods (minutes seconds), classes: Periods and Durations - Instants: represent a specific instant in time, so you can compute the number of minutes
between two instants, the class: Instants
What does the LocalDate.parse(String string) do?
to parse a string that matches the date (so string need to be in the order of ISO-
8601)
What does the LocalDate.of(YYYY-MM-DD) do?
to parse a string that matches the date (so string need to be in the order of ISO-
8601)
What are ZoneRules for?
With ZoneRules the class captures the current rules about daylight savings in various parts of the world. It gives answer on the question is the current ZoneId in daylight savings time?
What are ZoneRules for?
With ZoneRules the class captures the current rules about daylight savings in various parts of the world. It gives answer on the question is the current ZoneId in daylight savings time?
Which Adjustments are there?
You can add days and hours with handy methods of LocalDate and ZonedDateTime classes, suchs as
plusMinutes(). plusYears(), minusWeeks(), minusSeconds().
What are temporalAdjusters?
The class temporalAdjusters has a whole slew of handy methods to make a TemporalAdjuster for a variety of scenarios, such as firstDayOfNextYear(), lastDayOfMonth()
What is a Period?
The Period Class in Java class obtains a quantity or amount of time in terms of years, months and days.
What is the output of Period?
Output of Periods is P for instance P1D, P1Y
What will the minus() method do?
You can call the minus() method on ZonedDateTime and DateTime classes with an argument of a
Period to minus that period on the current DateTime.
What is a Duration?
A Duration object ( java. time. Duration ) represents a period of time between two Instant objects.
What is the output of a Duration?
If you print out the Duration object you will get something like this: PT1H18M. PT means period of
time, 1H18M, means 1 hour 18 minutes.
What is an Instance?
An instant represent an instant in time. (seconds and nano seconds)
How to create a LocalDate?
LocalDate.now();
LocalDate.of(2017, 8, 21);
LocalDate.parse(“2017-08-21”);
How to create a LocalTime?
LocalTime.now();
LocalTime.of(10, 19, 36);
LocalTime.parse(“10:19:36”);
How to create a LocalDateTime?
LocalDateTime.now();
LocalDateTime.of(aDate, aTime);
LocalDateTime.parse(“2017-04-08T10:19:36);
LocalDateTime.parse(aDateTime, a Formatter);
How to create a ZonedDateTime?
ZonedDateTime.now();
ZonedDateTime.of(aDateTime, ZoneId.of(aZoneString);
How to create a DateTimeFormatter?
DateTimeFormatter.ofPattern(“yyyy-MM-dd HH:mm”;
DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT).withLocale(aLocale);
How to create an Instant?
Instant.now();
zonedDateTime.toInstant();
aDateTime.toInstant();
how to create a Period?
Period.between(aDate1, aDate2);
Period.ofDays(2);
How to create a Duration?
Duration.between(aTime1, aTime2);
Duration.ofMinutes(3);
What are the key adjustments of LocalDate?
aDate.minusDays(3);
aDate.plusWeeks(2);
aDate.withYear(2018);
What are the key adjustments of LocalDate?
aTime.minus(3, ChronoUnit.MINUTES);
aTime.plusMinutes(3);
aTime.withHour(12);
What are the key adjustments of LocalDateTime?
aDateTime.minusDays(3);
aDateTime.plusMinutes(3);
aDateTime.plus(Duration.ofMinutes(4));
aDateTime.withMonth(2);
Which 2 Constructors does Locale have?
- Locale(String language)
- Locale(String language, String country)
What does getCountry(); return?
getCountry(); geeft de afkorting van het land terug.
What does getDisplayCountry() terug?
getDisplayCountry(); geeft de naam van het land
voluit terug. Geldt hetzelfde voor language.
Are DateTime object mutable?
- Datetime objects are immutable so you can’t modify it
When do you get ZoneRulesException?
- Je krijgt een ZoneRulesException bij een foute zoneId
Which 3 property files does java know?
- System level properties file (not on the exam)
- Java.util.Properties: makes it easy for a programmer to create and maintain property files for
whatever applications the programmer chooses.
- Java.util.ResourceBundle: that can use the Properties class to make it easier for a programmer to add localization and/or internationalization features to application.
What is the structure of a property file?
- Set of comments (# or !)
- Followed by a number of rows of tekst data (each row representing a key/value pair)
Key = value
Key : value
Key value
What wil the property.list(); return?
propertie.list(); will produce an output of a list of key/value pairs
What does the String getProperty(String key) method do?
Returns the property associated with the key
What does the void load(InputStream is) method do?
reads a property list (key and element pairs) from the input byte stream
What does the Object setProperty(String key, String value) method do?
This wel set the property
What does the void store(OutputStream out, String headerComment) method do?
writes this property list (key and element
pairs) in this Properties table to the output stream in a format suitable for loading into a Properties table using the
load(InputStream) method
What are 2 rules when using ResourceBundle?
- These files must end in “.properties”
- The end of the name before the “.properties” must be a string that start with an underscore
and then declares the Locale the file represents (for example: MyApp_nl.properties).
What happens when we use ResourceBundle.getBundle(); without a Locale?
- These files must end in “.properties”
- The end of the name before the “.properties” must be a string that start with an underscore
and then declares the Locale the file represents (for example: MyApp_nl.properties).
How does Java look for the bundles?
- Start with the full Locale requested (first .java then .properties)
- Then fallback to just Language (first .java then .properties)
- Then fallback to the default Locale (first .java then .properties)
- Then fallback to the default bundle (first .java then .properties)
- Then cry: MissingResourceException
