T - the type of the object managed by this initializer classpublic class CallableBackgroundInitializer<T> extends BackgroundInitializer<T>
A specialized BackgroundInitializer implementation that wraps a
Callable object.
An instance of this class is initialized with a Callable object when
it is constructed. The implementation of the initialize() method
defined in the super class delegates to this Callable so that the
Callable is executed in the background thread.
The java.util.concurrent.Callable interface is a standard mechanism
of the JDK to define tasks to be executed by another thread. The CallableBackgroundInitializer class allows combining this standard interface
with the background initializer API.
Usage of this class is very similar to the default usage pattern of the
BackgroundInitializer class: Just create an instance and provide the
Callable object to be executed, then call the initializer's
BackgroundInitializer.start() method. This causes the Callable to be executed in
another thread. When the results of the Callable are needed the
initializer's BackgroundInitializer.get() method can be called (which may block until
background execution is complete). The following code fragment shows a
typical usage example:
// a Callable that performs a complex computation
Callable<Integer> computationCallable = new MyComputationCallable();
// setup the background initializer
CallableBackgroundInitializer<Integer> initializer =
new CallableBackgroundInitializer(computationCallable);
initializer.start();
// Now do some other things. Initialization runs in a parallel thread
...
// Wait for the end of initialization and access the result
Integer result = initializer.get();
| Constructor and Description |
|---|
CallableBackgroundInitializer(Callable<T> call)
Creates a new instance of
CallableBackgroundInitializer and sets
the Callable to be executed in a background thread. |
CallableBackgroundInitializer(Callable<T> call,
ExecutorService exec)
Creates a new instance of
CallableBackgroundInitializer and
initializes it with the Callable to be executed in a background
thread and the ExecutorService for managing the background
execution. |
| Modifier and Type | Method and Description |
|---|---|
protected T |
initialize()
Performs initialization in a background thread.
|
get, getActiveExecutor, getExternalExecutor, getFuture, getTaskCount, isStarted, setExternalExecutor, startpublic CallableBackgroundInitializer(Callable<T> call)
CallableBackgroundInitializer and sets
the Callable to be executed in a background thread.call - the Callable (must not be null)IllegalArgumentException - if the Callable is nullpublic CallableBackgroundInitializer(Callable<T> call, ExecutorService exec)
CallableBackgroundInitializer and
initializes it with the Callable to be executed in a background
thread and the ExecutorService for managing the background
execution.call - the Callable (must not be null)exec - an external ExecutorService to be used for task
executionIllegalArgumentException - if the Callable is nullprotected T initialize() throws Exception
Callable passed at construction time of this
object.initialize in class BackgroundInitializer<T>Exception - if an error occursCopyright © 2001–2016 The Apache Software Foundation. All rights reserved.