@GwtCompatible public final class Tables extends Object
Table.
See the Guava User Guide article on Tables.
| Modifier and Type | Method and Description |
|---|---|
static <R |
immutableCell(R rowKey, C columnKey, V value)
Returns an immutable cell with the specified row key, column key, and value.
|
static <R |
newCustomTable(Map
Creates a table that uses the specified backing map and factory.
|
static <R |
transformValues(Table
Returns a view of a table where each value is transformed by a function.
|
static <R |
transpose(Table
Creates a transposed view of a given table that flips its row and column keys.
|
static <R |
unmodifiableRowSortedTable(RowSortedTable
Returns an unmodifiable view of the specified row-sorted table.
|
static <R |
unmodifiableTable(Table
Returns an unmodifiable view of the specified table.
|
public static <R,C ,V> Table .Cell <R ,C ,V> immutableCell(R rowKey, C columnKey, V value)
The returned cell is serializable.
rowKey - the row key to be associated with the returned cell
columnKey - the column key to be associated with the returned cell
value - the value to be associated with the returned cell
public static <R,C ,V> Table <C ,R ,V> transpose(Table <R ,C ,V> table)
get(columnKey, rowKey) on the generated table always returns the same value as calling
get(rowKey, columnKey) on the original table. Updating the original table changes the contents of the transposed table and vice versa.
The returned table supports update operations as long as the input table supports the analogous operation with swapped rows and columns. For example, in a HashBasedTable instance, rowKeySet().iterator() supports remove() but columnKeySet().iterator() doesn't. With a transposed HashBasedTable, it's the other way around.
@Beta public static <R,C ,V> Table <R ,C ,V> newCustomTable(Map <R ,Map <C ,V>> backingMap, Supplier <? extends Map <C ,V>> factory)
Map classes.
The factory-generated and backingMap classes determine the table iteration order. However, the table's row() method returns instances of a different class than factory.get() does.
Call this method only when the simpler factory methods in classes like HashBasedTable and TreeBasedTable won't suffice.
The views returned by the Table methods Table, Table, and Table 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.
The table is serializable if backingMap, factory, the maps generated by factory, and the table contents are all serializable.
Note: the table assumes complete ownership over of backingMap and the maps returned by factory. Those objects should not be manually updated and they should not use soft, weak, or phantom references.
backingMap - place to store the mapping from each row key to its corresponding column key / value map
factory - supplier of new, empty maps that will each hold all column key / value mappings for a given row key
IllegalArgumentException - if
backingMap is not empty
@Beta public static <R,C ,V1 ,V2> Table <R ,C ,V2> transformValues(Table <R ,C ,V1> fromTable, Function <? super V1 ,V2> function)
Changes in the underlying table are reflected in this view. Conversely, this view supports removal operations, and these are reflected in the underlying table.
It's acceptable for the underlying table to contain null keys, and even null values provided that the function is capable of accepting null input. The transformed table might contain null values, if the function sometimes gives a null result.
The returned table is not thread-safe or serializable, even if the underlying table is.
The function is applied lazily, invoked when needed. This is necessary for the returned table to be a view, but it means that the function will be applied many times for bulk operations like Table and Table.toString(). For this to perform well, function should be fast. To avoid lazy evaluation when the returned table doesn't need to be a view, copy the returned table into a new table of your choosing.
public static <R,C ,V> Table <R ,C ,V> unmodifiableTable(Table <? extends R ,? extends C ,? extends V> table)
UnsupportedOperationException.
The returned table will be serializable if the specified table is serializable.
Consider using an ImmutableTable, which is guaranteed never to change.
table - the table for which an unmodifiable view is to be returned
@Beta public static <R,C ,V> RowSortedTable <R ,C ,V> unmodifiableRowSortedTable(RowSortedTable <R ,? extends C ,? extends V> table)
UnsupportedOperationException.
The returned table will be serializable if the specified table is serializable.
table - the row-sorted table for which an unmodifiable view is to be returned