Link to Java 21 documentation

administration/logging.md

@@ -168,7 +168,7 @@ An example output of the last log statement above is:
 2016-06-04 16:28:39.482 [DEBUG] [org.openhab.core.model.script.heating] Bedroom: Temperature 21.3°C, Mode NORMAL
 ```
 
-Note that, in the last example above, inclusion and formatting of values is done using [Java Formatter String Syntax](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/Formatter.html).
+Note that, in the last example above, inclusion and formatting of values is done using [Java Formatter String Syntax](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/Formatter.html).
 
 ## Log4j configuration and logging into separate files
 

configuration/actions.md

@@ -61,7 +61,7 @@ You have different options to execute a command through an action.
   For example you could run `var ScriptResponse = executeCommandLine(Duration.ofSeconds(60), "path/to/my/script.sh");` would get executed and wait 1 minute for the output to be responded back and write it into the `ScriptResponse` variable.
 
 Other Durations than `ofSeconds` units are possible too.
-Check out the [Java Documentation](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/time/Duration.html?is-external=true) for possible units.
+Check out the [Java Documentation](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/time/Duration.html?is-external=true) for possible units.
 
 #### Scripts with parameters
 

configuration/items.md

@@ -257,7 +257,7 @@ If no square brackets are given and the Item is not linked to a channel, the Ite
 No text between the square brackets also implies no textual presentation.
 This is often meaningful when an Item is presented by a non-textual UI elements like a switch or a diagram.
 
-Formatting of the presentation is done applying [Java formatter class syntax](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/Formatter.html#syntax).
+Formatting of the presentation is done applying [Java formatter class syntax](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/Formatter.html#syntax).
 
 If square brackets are given, the leading `%` and the trailing formatter conversion are mandatory.
 Free text, like a unit, can be added before or after the formatter string.

configuration/jsr223.md

@@ -258,11 +258,11 @@ With `scriptExtension.get("automationManager")` the `automationManager` can be m
 |-------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `State`                 | [`org.openhab.core.types.State`](https://www.openhab.org/javadoc/latest/org/openhab/core/types/state)                                                                                                       |
 | `Command`               | [`org.openhab.core.types.Command`](https://www.openhab.org/javadoc/latest/org/openhab/core/types/command)                                                                                                   |
-| `URLEncoder`            | [`java.net.URLEncoder`](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/net/URLEncoder.html)                                                                                              |
-| `File`                  | [`java.io.File`](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/File.html)                                                                                                            |
-| `Files`                 | [`java.nio.file.Files`](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/nio/file/Files.html)                                                                                              |
-| `Path`                  | [`java.nio.file.Path`](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/nio/file/Path.html)                                                                                                |
-| `Paths`                 | [`java.nio.file.Paths`](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/nio/file/Paths.html)                                                                                              |
+| `URLEncoder`            | [`java.net.URLEncoder`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/net/URLEncoder.html)                                                                                              |
+| `File`                  | [`java.io.File`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html)                                                                                                            |
+| `Files`                 | [`java.nio.file.Files`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html)                                                                                              |
+| `Path`                  | [`java.nio.file.Path`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Path.html)                                                                                                |
+| `Paths`                 | [`java.nio.file.Paths`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Paths.html)                                                                                              |
 | `IncreaseDecreaseType`  | [`org.openhab.core.library.types.IncreaseDecreaseType`](https://www.openhab.org/javadoc/latest/org/openhab/core/library/types/increasedecreasetype)                                                         |
 | `DECREASE`              | `IncreaseDecreaseType` enum item                                                                                                                                                                            |
 | `INCREASE`              | `IncreaseDecreaseType` enum item                                                                                                                                                                            |

developers/guidelines.md

@@ -159,7 +159,7 @@ See [Default libraries](#default-libraries) for more details.
 1. Creation of threads must be avoided.
   Instead, resort into using existing schedulers which use pre-configured thread pools.
   If there is no suitable scheduler available, start a discussion in the forum about it rather than creating a thread by yourself.
-  For periodically executed jobs that do not require a fixed rate [scheduleWithFixedDelay](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/ScheduledExecutorService.html#scheduleWithFixedDelay(java.lang.Runnable,long,long,java.util.concurrent.TimeUnit)) should be preferred over [scheduleAtFixedRate](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/ScheduledExecutorService.html#scheduleAtFixedRate(java.lang.Runnable,long,long,java.util.concurrent.TimeUnit)).
+  For periodically executed jobs that do not require a fixed rate [scheduleWithFixedDelay](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/concurrent/ScheduledExecutorService.html#scheduleWithFixedDelay(java.lang.Runnable,long,long,java.util.concurrent.TimeUnit)) should be preferred over [scheduleAtFixedRate](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/concurrent/ScheduledExecutorService.html#scheduleAtFixedRate(java.lang.Runnable,long,long,java.util.concurrent.TimeUnit)).
 1. Bundles need to cleanly start and stop without throwing exceptions or malfunctioning.
   This can be tested by manually starting and stopping the bundle from the console (```stop <bundle-id>``` resp. ```start <bundle-id>```).
 1. Bundles must not require any substantial CPU time.

developers/osgi/osgi.md

@@ -42,7 +42,7 @@ More details about the OSGi architecture can be found at <https://www.osgi.org/d
 Modules (called **bundles**) are the smallest unit of modularization.
 Technically a bundle is a JAR file with additional meta information.
 This information is stored in file called [**manifest**](#important-definitions) file.
-The manifest file is part of the standard [JAR specification](https://docs.oracle.com/en/java/javase/17/docs/specs/jar/jar.html#jar-manifest), but OSGi adds additional metadata to it in form of specific headers.
+The manifest file is part of the standard [JAR specification](https://docs.oracle.com/en/java/javase/21/docs/specs/jar/jar.html#jar-manifest), but OSGi adds additional metadata to it in form of specific headers.
 The _Bundle-SymbolicName_ and the _Bundle-Version_ headers uniquely identify a bundle.
 In OSGi is allowed to have **bundles with same name, but different version running at the same time.**
 

developers/utils/events.md

@@ -152,7 +152,7 @@ A string representation of an event type can be found by a public member `TYPE`
 To subscribe to all available event types, use the public member `ALL_EVENT_TYPES` of the event subscriber interface.
 
 The event subscriber provides a `TopicEventFilter` which is a default openHAB `EventFilter` implementation that ensures filtering of events based on a topic.
-The argument of the filter is a [Java regular expression](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/regex/Pattern.html).
+The argument of the filter is a [Java regular expression](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/regex/Pattern.html).
 The filter method `EventFilter.apply()` will be called for each event on the event bus to which the event subscriber is subscribed (in the example above `ItemStateEvent` and `ItemCommandEvent`).
 If the filter applies (in the given example for all item events with the item name "ItemX"), the event will be received by the `EventSubscriber.receive()` method.
 Received events can be cast to the event implementation class for further processing.
@@ -167,7 +167,7 @@ The listing below summarizes some best practices in order to implement event sub
     To provide an event filter the method `getEventFilter()` can be overridden.
 - openHAB provides an `AbstractItemEventSubscriber` class in order to receive `ItemStateEvents` and `ItemCommandEvents` (more information can be obtained in the next chapter).
 - To filter events based on a topic the  `org.openhab.core.events.TopicEventFilter` implementation from the openHAB core bundle can be used.
-    The filtering is based on [Java regular expression](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/regex/Pattern.html).
+    The filtering is based on [Java regular expression](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/regex/Pattern.html).
 - The subscribed event types and the filter should be stored as class members (see example above) due to performance reasons.
 - If the subscribed event types are sufficient in order to receive all interested events, do not return any filter (in that case the method getFilter() returns null) due to performance reasons.
 - Avoid the creation of too many event subscribers.

ui/sitemaps.md

@@ -633,7 +633,7 @@ Adds a time-series chart object for the display of logged data.
 - `forceasitem` is used to show the value of a `Group` instead of showing a graph for each member (which is the default).
 
 - `yAxisDecimalPattern` is used to format the values on the y axis.
-    It accepts [DecimalFormat](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/text/DecimalFormat.html).
+    It accepts [DecimalFormat](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/text/DecimalFormat.html).
     For example with `#.##` a number has to decimals.
 
 **Other options to look out for:**