[LANG-501] There was a problem with inconsistent line endings in the last commit, so the svn:eol-style property was not set. Fixing now.
git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@883101 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Oliver Heger
parent
21df5c4fce
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63e4b09f23
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@ -1,127 +1,125 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang.concurrent;
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import java.util.concurrent.Callable;
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import java.util.concurrent.ExecutorService;
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/**
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* <p>
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* A specialized {@link BackgroundInitializer} implementation that wraps a
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* {@code Callable} object.
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* </p>
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* <p>
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* An instance of this class is initialized with a {@code Callable} object when
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* it is constructed. The implementation of the {@link #initialize()} method
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* defined in the super class delegates to this {@code Callable} so that the
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* {@code Callable} is executed in the background thread.
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* </p>
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* <p>
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* The {@code java.util.concurrent.Callable} interface is a standard mechanism
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* of the JDK to define tasks to be executed by another thread. The {@code
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* CallableBackgroundInitializer} class allows combining this standard interface
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* with the background initializer API.
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* </p>
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* <p>
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* Usage of this class is very similar to the default usage pattern of the
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* {@link BackgroundInitializer} class: Just create an instance and provide the
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* {@code Callable} object to be executed, then call the initializer's
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* {@link #start()} method. This causes the {@code Callable} to be executed in
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* another thread. When the results of the {@code Callable} are needed the
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* initializer's {@link #get()} method can be called (which may block until
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* background execution is complete). The following code fragment shows a
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* typical usage example:
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*
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* <pre>
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* // a Callable that performs a complex computation
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* Callable<Integer> computationCallable = new MyComputationCallable();
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* // setup the background initializer
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* CallableBackgroundInitializer<Integer> initializer =
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* new CallableBackgroundInitializer(computationCallable);
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* initializer.start();
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* // Now do some other things. Initialization runs in a parallel thread
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* ...
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* // Wait for the end of initialization and access the result
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* Integer result = initializer.get();
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* </pre>
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*
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* </p>
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*
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* @version $Id: $
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* @param <T> the type of the object managed by this initializer class
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*/
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public class CallableBackgroundInitializer<T> extends BackgroundInitializer<T> {
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/** The Callable to be executed. */
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private final Callable<T> callable;
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/**
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* Creates a new instance of {@code CallableBackgroundInitializer} and sets
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* the {@code Callable} to be executed in a background thread.
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*
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* @param call the {@code Callable} (must not be <b>null</b>)
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* @throws IllegalArgumentException if the {@code Callable} is <b>null</b>
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*/
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public CallableBackgroundInitializer(Callable<T> call) {
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checkCallable(call);
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callable = call;
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}
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/**
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* Creates a new instance of {@code CallableBackgroundInitializer} and
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* initializes it with the {@code Callable} to be executed in a background
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* thread and the {@code ExecutorService} for managing the background
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* execution.
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*
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* @param call the {@code Callable} (must not be <b>null</b>)
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* @param exec an external {@code ExecutorService} to be used for task
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* execution
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* @throws IllegalArgumentException if the {@code Callable} is <b>null</b>
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*/
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public CallableBackgroundInitializer(Callable<T> call, ExecutorService exec) {
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super(exec);
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checkCallable(call);
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callable = call;
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}
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/**
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* Performs initialization in a background thread. This implementation
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* delegates to the {@code Callable} passed at construction time of this
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* object.
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*
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* @return the result of the initialization
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* @throws Exception if an error occurs
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*/
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@Override
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protected T initialize() throws Exception {
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return callable.call();
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}
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/**
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* Tests the passed in {@code Callable} and throws an exception if it is
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* undefined.
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*
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* @param call the object to check
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* @throws IllegalArgumentException if the {@code Callable} is <b>null</b>
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*/
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private void checkCallable(Callable<T> call) {
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if (call == null) {
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throw new IllegalArgumentException("Callable must not be null!");
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}
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}
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}
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang.concurrent;
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import java.util.concurrent.Callable;
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import java.util.concurrent.ExecutorService;
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/**
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* <p>
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* A specialized {@link BackgroundInitializer} implementation that wraps a
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* {@code Callable} object.
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* </p>
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* <p>
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* An instance of this class is initialized with a {@code Callable} object when
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* it is constructed. The implementation of the {@link #initialize()} method
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* defined in the super class delegates to this {@code Callable} so that the
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* {@code Callable} is executed in the background thread.
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* </p>
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* <p>
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* The {@code java.util.concurrent.Callable} interface is a standard mechanism
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* of the JDK to define tasks to be executed by another thread. The {@code
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* CallableBackgroundInitializer} class allows combining this standard interface
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* with the background initializer API.
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* </p>
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* <p>
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* Usage of this class is very similar to the default usage pattern of the
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* {@link BackgroundInitializer} class: Just create an instance and provide the
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* {@code Callable} object to be executed, then call the initializer's
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* {@link #start()} method. This causes the {@code Callable} to be executed in
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* another thread. When the results of the {@code Callable} are needed the
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* initializer's {@link #get()} method can be called (which may block until
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* background execution is complete). The following code fragment shows a
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* typical usage example:
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*
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* <pre>
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* // a Callable that performs a complex computation
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* Callable<Integer> computationCallable = new MyComputationCallable();
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* // setup the background initializer
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* CallableBackgroundInitializer<Integer> initializer =
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* new CallableBackgroundInitializer(computationCallable);
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* initializer.start();
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* // Now do some other things. Initialization runs in a parallel thread
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* ...
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* // Wait for the end of initialization and access the result
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* Integer result = initializer.get();
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* </pre>
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*
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* </p>
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*
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* @version $Id$
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* @param <T> the type of the object managed by this initializer class
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*/
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public class CallableBackgroundInitializer<T> extends BackgroundInitializer<T> {
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/** The Callable to be executed. */
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private final Callable<T> callable;
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/**
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* Creates a new instance of {@code CallableBackgroundInitializer} and sets
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* the {@code Callable} to be executed in a background thread.
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*
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* @param call the {@code Callable} (must not be <b>null</b>)
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* @throws IllegalArgumentException if the {@code Callable} is <b>null</b>
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*/
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public CallableBackgroundInitializer(Callable<T> call) {
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checkCallable(call);
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callable = call;
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}
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/**
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* Creates a new instance of {@code CallableBackgroundInitializer} and
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* initializes it with the {@code Callable} to be executed in a background
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* thread and the {@code ExecutorService} for managing the background
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* execution.
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*
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* @param call the {@code Callable} (must not be <b>null</b>)
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* @param exec an external {@code ExecutorService} to be used for task
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* execution
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* @throws IllegalArgumentException if the {@code Callable} is <b>null</b>
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*/
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public CallableBackgroundInitializer(Callable<T> call, ExecutorService exec) {
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super(exec);
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checkCallable(call);
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callable = call;
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}
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/**
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* Performs initialization in a background thread. This implementation
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* delegates to the {@code Callable} passed at construction time of this
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* object.
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*
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* @return the result of the initialization
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* @throws Exception if an error occurs
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*/
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@Override
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protected T initialize() throws Exception {
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return callable.call();
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}
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/**
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* Tests the passed in {@code Callable} and throws an exception if it is
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* undefined.
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*
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* @param call the object to check
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* @throws IllegalArgumentException if the {@code Callable} is <b>null</b>
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*/
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private void checkCallable(Callable<T> call) {
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if (call == null) {
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throw new IllegalArgumentException("Callable must not be null!");
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}
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}
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}
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