Java tutorial
/* * Copyright 2015 Open Networking Laboratory * * 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 org.onosproject.store.consistent.impl; import java.util.Collection; import java.util.Map; import java.util.Set; import java.util.function.BiConsumer; import java.util.function.BiFunction; import java.util.function.Function; import java.util.stream.Collectors; import org.onosproject.store.service.ConsistentMap; import org.onosproject.store.service.Versioned; import com.google.common.collect.Collections2; import com.google.common.collect.Maps; /** * Standard java Map backed by a ConsistentMap. * * @param <K> key type * @param <V> value type */ public final class ConsistentMapBackedJavaMap<K, V> implements Map<K, V> { private final ConsistentMap<K, V> backingMap; public ConsistentMapBackedJavaMap(ConsistentMap<K, V> backingMap) { this.backingMap = backingMap; } @Override public int size() { return backingMap.size(); } @Override public boolean isEmpty() { return backingMap.isEmpty(); } @Override public boolean containsKey(Object key) { return backingMap.containsKey((K) key); } @Override public boolean containsValue(Object value) { return backingMap.containsValue((V) value); } @Override public V get(Object key) { return Versioned.valueOrElse(backingMap.get((K) key), null); } @Override public V getOrDefault(Object key, V defaultValue) { return Versioned.valueOrElse(backingMap.get((K) key), defaultValue); } @Override public V put(K key, V value) { return Versioned.valueOrElse(backingMap.put(key, value), null); } @Override public V putIfAbsent(K key, V value) { return Versioned.valueOrElse(backingMap.putIfAbsent(key, value), null); } @Override public V remove(Object key) { return Versioned.valueOrElse(backingMap.remove((K) key), null); } @Override public boolean remove(Object key, Object value) { return backingMap.remove((K) key, (V) value); } @Override public V replace(K key, V value) { throw new UnsupportedOperationException(); } @Override public boolean replace(K key, V oldValue, V newValue) { return backingMap.replace(key, oldValue, newValue); } @Override public void putAll(Map<? extends K, ? extends V> m) { m.forEach((k, v) -> { backingMap.put(k, v); }); } @Override public void clear() { backingMap.clear(); } @Override public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { return Versioned.valueOrElse(backingMap.compute(key, remappingFunction), null); } @Override public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) { return Versioned.valueOrElse(backingMap.computeIfAbsent(key, mappingFunction), null); } @Override public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { return Versioned.valueOrElse(backingMap.computeIfPresent(key, remappingFunction), null); } @Override public Set<K> keySet() { return backingMap.keySet(); } @Override public Collection<V> values() { return Collections2.transform(backingMap.values(), v -> v.value()); } @Override public Set<java.util.Map.Entry<K, V>> entrySet() { return backingMap.entrySet().stream() .map(entry -> Maps.immutableEntry(entry.getKey(), entry.getValue().value())) .collect(Collectors.toSet()); } @Override public void forEach(BiConsumer<? super K, ? super V> action) { entrySet().forEach(e -> action.accept(e.getKey(), e.getValue())); } @Override public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) { return computeIfPresent(key, (k, v) -> v == null ? value : remappingFunction.apply(v, value)); } }