com.google.common.cache.AbstractLoadingCache Maven / Gradle / Ivy
Show all versions of guava Show documentation
/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.common.cache;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.common.util.concurrent.UncheckedExecutionException;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
/**
* This class provides a skeletal implementation of the {@code Cache} interface to minimize the
* effort required to implement this interface.
*
* To implement a cache, the programmer needs only to extend this class and provide an
* implementation for the {@link #get(Object)} and {@link #getIfPresent} methods. {@link
* #getUnchecked}, {@link #get(Object, Callable)}, and {@link #getAll} are implemented in terms of
* {@code get}; {@link #getAllPresent} is implemented in terms of {@code getIfPresent}; {@link
* #putAll} is implemented in terms of {@link #put}, {@link #invalidateAll(Iterable)} is implemented
* in terms of {@link #invalidate}. The method {@link #cleanUp} is a no-op. All other methods throw
* an {@link UnsupportedOperationException}.
*
* @author Charles Fry
* @since 11.0
*/
@GwtIncompatible
public abstract class AbstractLoadingCache extends AbstractCache
implements LoadingCache {
/** Constructor for use by subclasses. */
protected AbstractLoadingCache() {}
@Override
public V getUnchecked(K key) {
try {
return get(key);
} catch (ExecutionException e) {
throw new UncheckedExecutionException(e.getCause());
}
}
@Override
public ImmutableMap getAll(Iterable keys) throws ExecutionException {
Map result = Maps.newLinkedHashMap();
for (K key : keys) {
if (!result.containsKey(key)) {
result.put(key, get(key));
}
}
return ImmutableMap.copyOf(result);
}
@Override
public final V apply(K key) {
return getUnchecked(key);
}
@Override
public void refresh(K key) {
throw new UnsupportedOperationException();
}
}