Package org.bardframework.time.temporal

Class TemporalQueriesJalali

java.lang.Object
org.bardframework.time.temporal.TemporalQueriesJalali
public final class TemporalQueriesJalali extends Object
Common implementations of TemporalQuery.

This class provides common implementations of TemporalQuery. These are defined here as they must be constants, and the definition of lambdas does not guarantee that. By assigning them once here, they become 'normal' Java constants.

Queries are a key tool for extracting information from temporal objects. They exist to externalize the process of querying, permitting different approaches, as per the strategy design pattern. Examples might be a query that checks if the date is the day before February 29th in a leap year, or calculates the number of days to your next birthday.

The TemporalField interface provides another mechanism for querying temporal objects. That interface is limited to returning a long. By contrast, queries can return any type.

There are two equivalent ways of using a TemporalQuery. The first is to invoke the method on this interface directly. The second is to use TemporalAccessor.query(TemporalQuery): 

   // these two lines are equivalent, but the second approach is recommended
   temporal = thisQuery.queryFrom(temporal);
   temporal = temporal.query(thisQuery);
It is recommended to use the second approach, query(TemporalQuery), as it is a lot clearer to read in code.

The most common implementations are method references, such as LocalDateJalali::from and ZoneId::from. Additional common queries are provided to return:

  • a LocalDateJalali,

  • Method Details

    • localDate

      public static TemporalQuery<LocalDateJalali> localDate()
      A query for LocalDateJalali returning null if not found.

      This returns a TemporalQuery that can be used to query a temporal object for the local date. The query will return null if the temporal object cannot supply a local date.

      The query implementation examines the EPOCH_DAY field and uses it to create a LocalDateJalali.

      The method ZoneOffset.from(TemporalAccessor) can be used as a TemporalQuery via a method reference, LocalDateJalali::from. This query and LocalDateJalali::from will return the same result if the temporal object contains a date. If the temporal object does not contain a date, then the method reference will throw an exception, whereas this query will return null.

      Returns:
      a query that can obtain the date of a temporal, not null