@GwtCompatible(serializable=true) public class HashBasedTable<R,C,V> extends Object
Implementation of Table
using hash tables.
The views returned by column(C)
, columnKeySet()
, and columnMap()
have iterators that don’t support remove()
. Otherwise, all optional operations are supported. Null row keys, columns keys, and values are not supported.
Lookups by row key are often faster than lookups by column key, because the data is stored in a Map<R, Map<C, V>>
. A method call like column(columnKey).get(rowKey)
still runs quickly, since the row key is provided. However, column(columnKey).size()
takes longer, since an iteration across all row keys occurs.
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.
See the Guava User Guide article on Table
.
Table.Cell<R,C,V>
Modifier and Type | Method and Description |
---|---|
Set<Table.Cell<R,C,V>> |
cellSet()
Returns a set of all row key / column key / value triplets.
|
void |
clear()
Removes all mappings from the table.
|
Map<R,V> |
column(C columnKey)
Returns a view of all mappings that have the given column key.
|
Set<C> |
columnKeySet()
Returns a set of column keys that have one or more values in the table.
|
Map<C,Map<R,V>> |
columnMap()
Returns a view that associates each column key with the corresponding map from row keys to values.
|
boolean |
contains(Object rowKey,
Object columnKey)
Returns
true if the table contains a mapping with the specified row and column keys. |
boolean |
containsColumn(Object columnKey)
Returns
true if the table contains a mapping with the specified column. |
boolean |
containsRow(Object rowKey)
Returns
true if the table contains a mapping with the specified row key. |
boolean |
containsValue(Object value)
Returns
true if the table contains a mapping with the specified value. |
static <R,C,V> HashBasedTable<R,C,V> |
create()
Creates an empty
HashBasedTable . |
static <R,C,V> HashBasedTable<R,C,V> |
create(int expectedRows,
int expectedCellsPerRow)
Creates an empty
HashBasedTable with the specified map sizes. |
static <R,C,V> HashBasedTable<R,C,V> |
create(Table<? extends R,? extends C,? extends V> table)
Creates a
HashBasedTable with the same mappings as the specified table. |
boolean |
equals(Object obj)
Compares the specified object with this table for equality.
|
V |
get(Object rowKey,
Object columnKey)
Returns the value corresponding to the given row and column keys, or
null if no such mapping exists. |
int |
hashCode()
Returns the hash code for this table.
|
boolean |
isEmpty()
Returns
true if the table contains no mappings. |
V |
put(R rowKey,
C columnKey,
V value)
Associates the specified value with the specified keys.
|
void |
putAll(Table<? extends R,? extends C,? extends V> table)
Copies all mappings from the specified table to this table.
|
V |
remove(Object rowKey,
Object columnKey)
Removes the mapping, if any, associated with the given keys.
|
Map<C,V> |
row(R rowKey)
Returns a view of all mappings that have the given row key.
|
Set<R> |
rowKeySet()
Returns a set of row keys that have one or more values in the table.
|
Map<R,Map<C,V>> |
rowMap()
Returns a view that associates each row key with the corresponding map from column keys to values.
|
int |
size()
Returns the number of row key / column key / value mappings in the table.
|
String |
toString()
Returns the string representation
rowMap().toString() . |
Collection<V> |
values()
Returns a collection of all values, which may contain duplicates.
|
public static <R,C,V> HashBasedTable<R,C,V> create()
Creates an empty HashBasedTable
.
public static <R,C,V> HashBasedTable<R,C,V> create(int expectedRows, int expectedCellsPerRow)
Creates an empty HashBasedTable
with the specified map sizes.
expectedRows
- the expected number of distinct row keysexpectedCellsPerRow
- the expected number of column key / value mappings in each rowIllegalArgumentException
- if expectedRows
or expectedCellsPerRow
is negativepublic static <R,C,V> HashBasedTable<R,C,V> create(Table<? extends R,? extends C,? extends V> table)
Creates a HashBasedTable
with the same mappings as the specified table.
table
- the table to copyNullPointerException
- if any of the row keys, column keys, or values in table
is nullpublic boolean contains(@Nullable Object rowKey, @Nullable Object columnKey)
Table
Returns true
if the table contains a mapping with the specified row and column keys.
public boolean containsColumn(@Nullable Object columnKey)
Table
Returns true
if the table contains a mapping with the specified column.
containsColumn
in interface Table<R,C,V>
columnKey
- key of column to search forpublic boolean containsRow(@Nullable Object rowKey)
Table
Returns true
if the table contains a mapping with the specified row key.
containsRow
in interface Table<R,C,V>
rowKey
- key of row to search forpublic boolean containsValue(@Nullable Object value)
Table
Returns true
if the table contains a mapping with the specified value.
containsValue
in interface Table<R,C,V>
value
- value to search forpublic V get(@Nullable Object rowKey, @Nullable Object columnKey)
Table
Returns the value corresponding to the given row and column keys, or null
if no such mapping exists.
public boolean equals(@Nullable Object obj)
Table
Compares the specified object with this table for equality. Two tables are equal when their cell views, as returned by Table.cellSet()
, are equal.
public V remove(@Nullable Object rowKey, @Nullable Object columnKey)
Table
Removes the mapping, if any, associated with the given keys.
public boolean isEmpty()
Table
Returns true
if the table contains no mappings.
public int size()
Table
Returns the number of row key / column key / value mappings in the table.
public void clear()
Table
Removes all mappings from the table.
public V put(R rowKey, C columnKey, V value)
Table
Associates the specified value with the specified keys. If the table already contained a mapping for those keys, the old value is replaced with the specified value.
put
in interface Table<R,C,V>
rowKey
- row key that the value should be associated withcolumnKey
- column key that the value should be associated withvalue
- value to be associated with the specified keysnull
if no mapping existed for the keyspublic Set<Table.Cell<R,C,V>> cellSet()
Returns a set of all row key / column key / value triplets. Changes to the returned set will update the underlying table, and vice versa. The cell set does not support the add
or addAll
methods.
The set's iterator traverses the mappings for the first row, the mappings for the second row, and so on.
Each cell is an immutable snapshot of a row key / column key / value mapping, taken at the time the cell is returned by a method call to the set or its iterator.
public Map<C,V> row(R rowKey)
Table
Returns a view of all mappings that have the given row key. For each row key / column key / value mapping in the table with that row key, the returned map associates the column key with the value. If no mappings in the table have the provided row key, an empty map is returned.
Changes to the returned map will update the underlying table, and vice versa.
public Map<R,V> column(C columnKey)
Returns a view of all mappings that have the given column key. For each row key / column key / value mapping in the table with that column key, the returned map associates the row key with the value. If no mappings in the table have the provided column key, an empty map is returned.
Changes to the returned map will update the underlying table, and vice versa.
The returned map's views have iterators that don't support
remove()
.
public Set<R> rowKeySet()
Table
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.
public Set<C> columnKeySet()
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.
The returned set has an iterator that does not support remove()
.
The set's iterator traverses the columns of the first row, the columns of the second row, etc., skipping any columns that have appeared previously.
columnKeySet
in interface Table<R,C,V>
public Collection<V> values()
Returns a collection of all values, which may contain duplicates. Changes to the returned collection will update the underlying table, and vice versa.
The collection's iterator traverses the values for the first row, the values for the second row, and so on.
public Map<R,Map<C,V>> rowMap()
Table
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 put()
or putAll()
, or setValue()
on its entries.
In contrast, the maps returned by rowMap().get()
have the same behavior as those returned by Table.row(R)
. Those maps may support setValue()
, put()
, and putAll()
.
public Map<C,Map<R,V>> columnMap()
Table
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 put()
or putAll()
, or setValue()
on its entries.
In contrast, the maps returned by columnMap().get()
have the same behavior as those returned by Table.column(C)
. Those maps may support setValue()
, put()
, and putAll()
.
public void putAll(Table<? extends R,? extends C,? extends V> table)
Table
Copies all mappings from the specified table to this table. The effect is equivalent to calling Table.put(R, C, V)
with each row key / column key / value mapping in table
.
public int hashCode()
Table
Returns the hash code for this table. The hash code of a table is defined as the hash code of its cell view, as returned by Table.cellSet()
.