TemporalQuery

@FunctionalInterface interface TemporalQuery<R : Any!>

Strategy for querying a temporal object.

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);
  

The most common implementations are method references, such as LocalDate::from and ZoneId::from. Additional common queries are provided as static methods in TemporalQueries.

Summary

Public methods

abstract fun queryFrom(temporal: TemporalAccessor!): R

// these two lines are equivalent, but the second approach is recommended
    temporal = thisQuery.queryFrom(temporal);
    temporal = temporal.query(thisQuery);