/*
* 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 static com.google.common.collect.
CollectPreconditions.checkNonnegative;
import com.google.common.annotations.
GwtCompatible;
import com.google.common.base.
Supplier;
import java.io.
Serializable;
import java.util.
HashMap;
import java.util.
Map;
import javax.annotation.
Nullable;
/**
* Implementation of {@link Table} using hash tables.
*
* <p>The views returned by {@link #column}, {@link #columnKeySet()}, and {@link
* #columnMap()} have iterators that don't support {@code remove()}. Otherwise,
* all optional operations are supported. Null row keys, columns keys, and
* values are not supported.
*
* <p>Lookups by row key are often faster than lookups by column key, because
* the data is stored in a {@code Map<R, Map<C, V>>}. A method call like {@code
* column(columnKey).get(rowKey)} still runs quickly, since the row key is
* provided. However, {@code column(columnKey).size()} takes longer, since an
* iteration across all row keys occurs.
*
* <p>Note that this implementation is not synchronized. If multiple threads
* access this table concurrently and one of the threads modifies the table, it
* must be synchronized externally.
*
* <p>See the Guava User Guide article on <a href=
* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Table">
* {@code Table}</a>.
*
* @author Jared Levy
* @since 7.0
*/
@
GwtCompatible(serializable = true)
public class
HashBasedTable<R, C, V> extends
StandardTable<R, C, V> {
private static class
Factory<C, V>
implements
Supplier<
Map<C, V>>,
Serializable {
final int
expectedSize;
Factory(int
expectedSize) {
this.
expectedSize =
expectedSize;
}
@
Override
public
Map<C, V>
get() {
return
Maps.
newHashMapWithExpectedSize(
expectedSize);
}
private static final long
serialVersionUID = 0;
}
/**
* Creates an empty {@code HashBasedTable}.
*/
public static <R, C, V>
HashBasedTable<R, C, V>
create() {
return new
HashBasedTable<R, C, V>(
new
HashMap<R,
Map<C, V>>(), new
Factory<C, V>(0));
}
/**
* Creates an empty {@code HashBasedTable} with the specified map sizes.
*
* @param expectedRows the expected number of distinct row keys
* @param expectedCellsPerRow the expected number of column key / value
* mappings in each row
* @throws IllegalArgumentException if {@code expectedRows} or {@code
* expectedCellsPerRow} is negative
*/
public static <R, C, V>
HashBasedTable<R, C, V>
create(
int
expectedRows, int
expectedCellsPerRow) {
checkNonnegative(
expectedCellsPerRow, "expectedCellsPerRow");
Map<R,
Map<C, V>>
backingMap =
Maps.
newHashMapWithExpectedSize(
expectedRows);
return new
HashBasedTable<R, C, V>(
backingMap, new
Factory<C, V>(
expectedCellsPerRow));
}
/**
* Creates a {@code HashBasedTable} with the same mappings as the specified
* table.
*
* @param table the table to copy
* @throws NullPointerException if any of the row keys, column keys, or values
* in {@code table} is null
*/
public static <R, C, V>
HashBasedTable<R, C, V>
create(
Table<? extends R, ? extends C, ? extends V>
table) {
HashBasedTable<R, C, V>
result =
create();
result.
putAll(
table);
return
result;
}
HashBasedTable(
Map<R,
Map<C, V>>
backingMap,
Factory<C, V>
factory) {
super(
backingMap,
factory);
}
// Overriding so NullPointerTester test passes.
@
Override public boolean
contains(
@
Nullable Object rowKey, @
Nullable Object columnKey) {
return super.contains(
rowKey,
columnKey);
}
@
Override public boolean
containsColumn(@
Nullable Object columnKey) {
return super.containsColumn(
columnKey);
}
@
Override public boolean
containsRow(@
Nullable Object rowKey) {
return super.containsRow(
rowKey);
}
@
Override public boolean
containsValue(@
Nullable Object value) {
return super.containsValue(
value);
}
@
Override public V
get(@
Nullable Object rowKey, @
Nullable Object columnKey) {
return super.get(
rowKey,
columnKey);
}
@
Override public boolean
equals(@
Nullable Object obj) {
return super.equals(
obj);
}
@
Override public V
remove(
@
Nullable Object rowKey, @
Nullable Object columnKey) {
return super.remove(
rowKey,
columnKey);
}
private static final long
serialVersionUID = 0;
}