Module java.base
Package java.time.temporal

Interface TemporalQuery<R>

Type Parameters:
R - the type returned from the query
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface TemporalQuery<R>
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);
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 LocalDate::from and ZoneId::from. Additional common queries are provided as static methods in TemporalQueries.

Implementation Requirements:
This interface places no restrictions on the mutability of implementations, however immutability is strongly recommended.
Since:
1.8