程序包 java.time.temporal

接口 TemporalQuery<R>

类型参数:

R - the type returned from the query

函数接口:

这是一个函数接口, 因此可用作 lambda 表达式或方法引用的赋值目标。

@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.

从以下版本开始:

1.8

方法概要

限定符和类型	方法	说明
R	queryFrom(TemporalAccessor temporal)	Queries the specified temporal object.

方法详细资料

queryFrom

R queryFrom(TemporalAccessor temporal)

Queries the specified temporal object.

This queries the specified temporal object to return an object using the logic encapsulated in the implementing class. 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.

There are two equivalent ways of using this method. The first is to invoke this method 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.

参数:

temporal - the temporal object to query, not null

返回:

the queried value, may return null to indicate not found

抛出:

DateTimeException - if unable to query

ArithmeticException - if numeric overflow occurs