303 lines
9.4 KiB
Java
303 lines
9.4 KiB
Java
/*
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* Copyright (C) 2008 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* 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 com.google.common.collect;
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import java.util.Collection;
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import java.util.Map;
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import java.util.Set;
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import javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.base.Objects;
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/**
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* A collection that associates an ordered pair of keys, called a row key and a
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* column key, with a single value. A table may be sparse, with only a small
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* fraction of row key / column key pairs possessing a corresponding value.
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*
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* <p>
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* The mappings corresponding to a given row key may be viewed as a {@link Map}
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* whose keys are the columns. The reverse is also available, associating a
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* column with a row key / value map. Note that, in some implementations, data
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* access by column key may have fewer supported operations or worse performance
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* than data access by row key.
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*
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* <p>
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* The methods returning collections or maps always return views of the
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* underlying table. Updating the table can change the contents of those
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* collections, and updating the collections will change the table.
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*
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* <p>
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* All methods that modify the table are optional, and the views returned by the
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* table may or may not be modifiable. When modification isn't supported, those
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* methods will throw an {@link UnsupportedOperationException}.
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*
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* <p>
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* See the Guava User Guide article on <a href=
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* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Table">
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* {@code Table}</a>.
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*
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* @author Jared Levy
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* @param <R> the type of the table row keys
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* @param <C> the type of the table column keys
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* @param <V> the type of the mapped values
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* @since 7.0
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*/
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@GwtCompatible
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public interface Table<R, C, V> {
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// TODO(jlevy): Consider adding methods similar to ConcurrentMap methods.
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// Accessors
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/**
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* Returns {@code true} if the table contains a mapping with the specified row
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* and column keys.
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*
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* @param rowKey key of row to search for
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* @param columnKey key of column to search for
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*/
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boolean contains(@Nullable Object rowKey, @Nullable Object columnKey);
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/**
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* Returns {@code true} if the table contains a mapping with the specified row
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* key.
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*
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* @param rowKey key of row to search for
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*/
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boolean containsRow(@Nullable Object rowKey);
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/**
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* Returns {@code true} if the table contains a mapping with the specified
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* column.
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*
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* @param columnKey key of column to search for
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*/
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boolean containsColumn(@Nullable Object columnKey);
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/**
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* Returns {@code true} if the table contains a mapping with the specified
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* value.
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*
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* @param value value to search for
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*/
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boolean containsValue(@Nullable Object value);
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/**
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* Returns the value corresponding to the given row and column keys, or
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* {@code null} if no such mapping exists.
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*
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* @param rowKey key of row to search for
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* @param columnKey key of column to search for
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*/
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V get(@Nullable Object rowKey, @Nullable Object columnKey);
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/** Returns {@code true} if the table contains no mappings. */
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boolean isEmpty();
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/**
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* Returns the number of row key / column key / value mappings in the table.
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*/
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int size();
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/**
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* Compares the specified object with this table for equality. Two tables are
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* equal when their cell views, as returned by {@link #cellSet}, are equal.
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*/
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@Override
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boolean equals(@Nullable Object obj);
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/**
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* Returns the hash code for this table. The hash code of a table is defined as
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* the hash code of its cell view, as returned by {@link #cellSet}.
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*/
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@Override
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int hashCode();
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// Mutators
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/** Removes all mappings from the table. */
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void clear();
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/**
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* Associates the specified value with the specified keys. If the table already
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* contained a mapping for those keys, the old value is replaced with the
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* specified value.
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*
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* @param rowKey row key that the value should be associated with
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* @param columnKey column key that the value should be associated with
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* @param value value to be associated with the specified keys
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* @return the value previously associated with the keys, or {@code null} if no
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* mapping existed for the keys
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*/
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V put(R rowKey, C columnKey, V value);
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/**
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* Copies all mappings from the specified table to this table. The effect is
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* equivalent to calling {@link #put} with each row key / column key / value
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* mapping in {@code table}.
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*
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* @param table the table to add to this table
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*/
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void putAll(Table<? extends R, ? extends C, ? extends V> table);
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/**
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* Removes the mapping, if any, associated with the given keys.
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*
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* @param rowKey row key of mapping to be removed
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* @param columnKey column key of mapping to be removed
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* @return the value previously associated with the keys, or {@code null} if no
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* such value existed
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*/
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V remove(@Nullable Object rowKey, @Nullable Object columnKey);
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// Views
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/**
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* Returns a view of all mappings that have the given row key. For each row key
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* / column key / value mapping in the table with that row key, the returned map
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* associates the column key with the value. If no mappings in the table have
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* the provided row key, an empty map is returned.
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*
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* <p>
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* Changes to the returned map will update the underlying table, and vice versa.
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*
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* @param rowKey key of row to search for in the table
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* @return the corresponding map from column keys to values
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*/
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Map<C, V> row(R rowKey);
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/**
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* Returns a view of all mappings that have the given column key. For each row
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* key / column key / value mapping in the table with that column key, the
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* returned map associates the row key with the value. If no mappings in the
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* table have the provided column key, an empty map is returned.
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*
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* <p>
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* Changes to the returned map will update the underlying table, and vice versa.
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*
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* @param columnKey key of column to search for in the table
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* @return the corresponding map from row keys to values
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*/
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Map<R, V> column(C columnKey);
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/**
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* Returns a set of all row key / column key / value triplets. Changes to the
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* returned set will update the underlying table, and vice versa. The cell set
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* does not support the {@code add} or {@code addAll} methods.
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*
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* @return set of table cells consisting of row key / column key / value
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* triplets
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*/
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Set<Cell<R, C, V>> cellSet();
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/**
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* Returns a set of row keys that have one or more values in the table. Changes
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* to the set will update the underlying table, and vice versa.
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*
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* @return set of row keys
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*/
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Set<R> rowKeySet();
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/**
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* Returns a set of column keys that have one or more values in the table.
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* Changes to the set will update the underlying table, and vice versa.
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*
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* @return set of column keys
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*/
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Set<C> columnKeySet();
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/**
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* Returns a collection of all values, which may contain duplicates. Changes to
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* the returned collection will update the underlying table, and vice versa.
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*
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* @return collection of values
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*/
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Collection<V> values();
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/**
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* Returns a view that associates each row key with the corresponding map from
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* column keys to values. Changes to the returned map will update this table.
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* The returned map does not support {@code put()} or {@code putAll()}, or
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* {@code setValue()} on its entries.
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*
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* <p>
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* In contrast, the maps returned by {@code rowMap().get()} have the same
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* behavior as those returned by {@link #row}. Those maps may support {@code
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* setValue()}, {@code put()}, and {@code putAll()}.
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*
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* @return a map view from each row key to a secondary map from column keys to
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* values
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*/
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Map<R, Map<C, V>> rowMap();
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/**
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* Returns a view that associates each column key with the corresponding map
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* from row keys to values. Changes to the returned map will update this table.
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* The returned map does not support {@code put()} or {@code putAll()}, or
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* {@code setValue()} on its entries.
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*
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* <p>
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* In contrast, the maps returned by {@code columnMap().get()} have the same
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* behavior as those returned by {@link #column}. Those maps may support
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* {@code setValue()}, {@code put()}, and {@code putAll()}.
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*
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* @return a map view from each column key to a secondary map from row keys to
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* values
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*/
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Map<C, Map<R, V>> columnMap();
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/**
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* Row key / column key / value triplet corresponding to a mapping in a table.
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*
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* @since 7.0
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*/
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interface Cell<R, C, V> {
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/**
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* Returns the row key of this cell.
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*/
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R getRowKey();
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/**
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* Returns the column key of this cell.
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*/
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C getColumnKey();
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/**
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* Returns the value of this cell.
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*/
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V getValue();
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/**
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* Compares the specified object with this cell for equality. Two cells are
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* equal when they have equal row keys, column keys, and values.
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*/
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@Override
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boolean equals(@Nullable Object obj);
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/**
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* Returns the hash code of this cell.
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*
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* <p>
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* The hash code of a table cell is equal to
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* {@link Objects#hashCode}{@code (e.getRowKey(), e.getColumnKey(), e.getValue())}.
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*/
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@Override
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int hashCode();
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}
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}
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