Java example source code file (Table.java)

This example Java source code file (Table.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, canignorereturnvalue, cell, collection, gwtcompatible, map, nullable, object, override, set, table, util

The Table.java Java example source code

/*
 * Copyright (C) 2008 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.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Objects;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

import java.util.Collection;
import java.util.Map;
import java.util.Set;

import javax.annotation.Nullable;

/**
 * A collection that associates an ordered pair of keys, called a row key and a
 * column key, with a single value. A table may be sparse, with only a small
 * fraction of row key / column key pairs possessing a corresponding value.
 *
 * <p>The mappings corresponding to a given row key may be viewed as a {@link
 * Map} whose keys are the columns. The reverse is also available, associating a
 * column with a row key / value map. Note that, in some implementations, data
 * access by column key may have fewer supported operations or worse performance
 * than data access by row key.
 *
 * <p>The methods returning collections or maps always return views of the
 * underlying table. Updating the table can change the contents of those
 * collections, and updating the collections will change the table.
 *
 * <p>All methods that modify the table are optional, and the views returned by
 * the table may or may not be modifiable. When modification isn't supported,
 * those methods will throw an {@link UnsupportedOperationException}.
 *
 * <p>See the Guava User Guide article on  cellSet();

  /**
   * Returns a set of row keys that have one or more values in the table.
   * Changes to the set will update the underlying table, and vice versa.
   *
   * @return set of row keys
   */
  Set<R> rowKeySet();

  /**
   * Returns a set of column keys that have one or more values in the table.
   * Changes to the set will update the underlying table, and vice versa.
   *
   * @return set of column keys
   */
  Set<C> columnKeySet();

  /**
   * Returns a collection of all values, which may contain duplicates. Changes
   * to the returned collection will update the underlying table, and vice
   * versa.
   *
   * @return collection of values
   */
  Collection<V> values();

  /**
   * Returns a view that associates each row key with the corresponding map from
   * column keys to values. Changes to the returned map will update this table.
   * The returned map does not support {@code put()} or {@code putAll()}, or
   * {@code setValue()} on its entries.
   *
   * <p>In contrast, the maps returned by {@code rowMap().get()} have the same
   * behavior as those returned by {@link #row}. Those maps may support {@code
   * setValue()}, {@code put()}, and {@code putAll()}.
   *
   * @return a map view from each row key to a secondary map from column keys to
   *     values
   */
  Map<R, Map rowMap();

  /**
   * Returns a view that associates each column key with the corresponding map
   * from row keys to values. Changes to the returned map will update this
   * table. The returned map does not support {@code put()} or {@code putAll()},
   * or {@code setValue()} on its entries.
   *
   * <p>In contrast, the maps returned by {@code columnMap().get()} have the
   * same behavior as those returned by {@link #column}. Those maps may support
   * {@code setValue()}, {@code put()}, and {@code putAll()}.
   *
   * @return a map view from each column key to a secondary map from row keys to
   *     values
   */
  Map<C, Map columnMap();

  /**
   * Row key / column key / value triplet corresponding to a mapping in a table.
   *
   * @since 7.0
   */
  interface Cell<R, C, V> {
    /**
     * Returns the row key of this cell.
     */
    @Nullable
    R getRowKey();

    /**
     * Returns the column key of this cell.
     */
    @Nullable
    C getColumnKey();

    /**
     * Returns the value of this cell.
     */
    @Nullable
    V getValue();

    /**
     * Compares the specified object with this cell for equality. Two cells are
     * equal when they have equal row keys, column keys, and values.
     */
    @Override
    boolean equals(@Nullable Object obj);

    /**
     * Returns the hash code of this cell.
     *
     * <p>The hash code of a table cell is equal to {@link
     * Objects#hashCode}{@code (e.getRowKey(), e.getColumnKey(), e.getValue())}.
     */
    @Override
    int hashCode();
  }
}