/*
 * 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 static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import java.util.AbstractMap.SimpleImmutableEntry;
import org.checkerframework.checker.nullness.qual.Nullable;

A notification of the removal of a single entry. The key and/or value may be null if they were
already garbage collected.
Like other Entry instances associated with CacheBuilder, this class holds strong references to the key and value, regardless of the type of references the cache may be using. 
Author:
Charles Fry
Since:
10.0/**
 * A notification of the removal of a single entry. The key and/or value may be null if they were
 * already garbage collected.
 *
 * <p>Like other {@code Entry} instances associated with {@code CacheBuilder}, this class holds
 * strong references to the key and value, regardless of the type of references the cache may be
 * using.
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible
public final class RemovalNotification<K, V> extends SimpleImmutableEntry<K, V> {
  private final RemovalCause cause;

  
Creates a new RemovalNotification for the given key/value pair, with the given cause for the removal. The key and/or value may be 
null if they were already garbage collected. 
Since:
19.0/**
   * Creates a new {@code RemovalNotification} for the given {@code key}/{@code value} pair, with
   * the given {@code cause} for the removal. The {@code key} and/or {@code value} may be {@code
   * null} if they were already garbage collected.
   *
   * @since 19.0
   */
  public static <K, V> RemovalNotification<K, V> create(
      @Nullable K key, @Nullable V value, RemovalCause cause) {
    return new RemovalNotification(key, value, cause);
  }

  private RemovalNotification(@Nullable K key, @Nullable V value, RemovalCause cause) {
    super(key, value);
    this.cause = checkNotNull(cause);
  }

  
Returns the cause for which the entry was removed. /** Returns the cause for which the entry was removed. */
  public RemovalCause getCause() {
    return cause;
  }

  
Returns true if there was an automatic removal due to eviction (the cause is neither RemovalCause.EXPLICIT nor RemovalCause.REPLACED). /**
   * Returns {@code true} if there was an automatic removal due to eviction (the cause is neither
   * {@link RemovalCause#EXPLICIT} nor {@link RemovalCause#REPLACED}).
   */
  public boolean wasEvicted() {
    return cause.wasEvicted();
  }

  private static final long serialVersionUID = 0;
}