Stay organized with collections
Save and categorize content based on your preferences.
TemporalQuery
public
interface
TemporalQuery
| java.time.temporal.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.
Summary
Public methods
queryFrom
public abstract 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.
Implementation Requirements:
- The implementation must take the input object and query it.
The implementation defines the logic of the query and is responsible for
documenting that logic.
It may use any method on
TemporalAccessor to determine the result.
The input object must not be altered.
The input temporal object may be in a calendar system other than ISO.
Implementations may choose to document compatibility with other calendar systems,
or reject non-ISO temporal objects by querying the chronology.
This method may be called from multiple threads in parallel.
It must be thread-safe when invoked.
| Parameters |
|---|
temporal |
TemporalAccessor: the temporal object to query, not null |
| Returns |
|---|
R |
the queried value, may return null to indicate not found |
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-02-10 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-02-10 UTC."],[],[],null,["# TemporalQuery\n\nAdded in [API level 26](/guide/topics/manifest/uses-sdk-element#ApiLevels) \n\nTemporalQuery\n=============\n\n\n`\npublic\n\n\ninterface\nTemporalQuery\n`\n\n\n`\n\n\n`\n\n|---------------------------------------|\n| java.time.temporal.TemporalQuery\\\u003cR\\\u003e |\n\n\u003cbr /\u003e\n\n*** ** * ** ***\n\nStrategy for querying a temporal object.\n\n\nQueries are a key tool for extracting information from temporal objects.\nThey exist to externalize the process of querying, permitting different\napproaches, as per the strategy design pattern.\nExamples might be a query that checks if the date is the day before February 29th\nin a leap year, or calculates the number of days to your next birthday.\n\n\nThe [TemporalField](/reference/java/time/temporal/TemporalField) interface provides another mechanism for querying\ntemporal objects. That interface is limited to returning a `long`.\nBy contrast, queries can return any type.\n\n\nThere are two equivalent ways of using a `TemporalQuery`.\nThe first is to invoke the method on this interface directly.\nThe second is to use [TemporalAccessor.query(TemporalQuery)](/reference/java/time/temporal/TemporalAccessor#query(java.time.temporal.TemporalQuery\u003cR\u003e)): \n\n```\n // these two lines are equivalent, but the second approach is recommended\n temporal = thisQuery.queryFrom(temporal);\n temporal = temporal.query(thisQuery);\n \n```\nIt is recommended to use the second approach, `query(TemporalQuery)`, as it is a lot clearer to read in code.\n\n\nThe most common implementations are method references, such as\n`LocalDate::from` and `ZoneId::from`.\nAdditional common queries are provided as static methods in [TemporalQueries](/reference/java/time/temporal/TemporalQueries).\n\nSummary\n-------\n\n| ### Public methods ||\n|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| ` abstract R` | ` `[queryFrom](/reference/java/time/temporal/TemporalQuery#queryFrom(java.time.temporal.TemporalAccessor))`(`[TemporalAccessor](/reference/java/time/temporal/TemporalAccessor)` temporal) ` Queries the specified temporal object. |\n\nPublic methods\n--------------\n\n### queryFrom\n\nAdded in [API level 26](/guide/topics/manifest/uses-sdk-element#ApiLevels) \n\n```\npublic abstract R queryFrom (TemporalAccessor temporal)\n```\n\nQueries the specified temporal object.\n\n\nThis queries the specified temporal object to return an object using the logic\nencapsulated in the implementing class.\nExamples might be a query that checks if the date is the day before February 29th\nin a leap year, or calculates the number of days to your next birthday.\n\n\nThere are two equivalent ways of using this method.\nThe first is to invoke this method directly.\nThe second is to use [TemporalAccessor.query(TemporalQuery)](/reference/java/time/temporal/TemporalAccessor#query(java.time.temporal.TemporalQuery\u003cR\u003e)): \n\n```\n // these two lines are equivalent, but the second approach is recommended\n temporal = thisQuery.queryFrom(temporal);\n temporal = temporal.query(thisQuery);\n \n```\nIt is recommended to use the second approach, `query(TemporalQuery)`, as it is a lot clearer to read in code.\n\n\u003cbr /\u003e\n\n\u003cbr /\u003e\n\n##### Implementation Requirements:\n\n- The implementation must take the input object and query it. The implementation defines the logic of the query and is responsible for documenting that logic. It may use any method on `TemporalAccessor` to determine the result. The input object must not be altered.\n\n\n The input temporal object may be in a calendar system other than ISO.\n Implementations may choose to document compatibility with other calendar systems,\n or reject non-ISO temporal objects by [querying the chronology](/reference/java/time/temporal/TemporalQueries#chronology()).\n\n\n This method may be called from multiple threads in parallel.\n It must be thread-safe when invoked.\n\n| Parameters ||\n|------------|-------------------------------------------------------------------|\n| `temporal` | `TemporalAccessor`: the temporal object to query, not null \u003cbr /\u003e |\n\n| Returns ||\n|-----|-----------------------------------------------------------------|\n| `R` | the queried value, may return null to indicate not found \u003cbr /\u003e |\n\n| Throws ||\n|-----------------------------------------------------------------|----------------------------|\n| [DateTimeException](/reference/java/time/DateTimeException) | if unable to query |\n| [ArithmeticException](/reference/java/lang/ArithmeticException) | if numeric overflow occurs |"]]
