HashBasedTable

java.lang.Object
- com.google.common.collect.HashBasedTable<R,C,V>

All Implemented Interfaces:

Table<R,C,V>, Serializable
```
@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.

Since:

7.0

See Also:

Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from interface com.google.common.collect.Table
  Table.Cell<R,C,V>

Method Summary

All Methods

Static Methods

Instance Methods

Concrete Methods
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.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Method Detail
  - create
```
public static <R,C,V> HashBasedTable<R,C,V> create()
```
    Creates an empty HashBasedTable.
  - create
```
public static <R,C,V> HashBasedTable<R,C,V> create(int expectedRows,
                                                   int expectedCellsPerRow)
```
    Creates an empty HashBasedTable with the specified map sizes.
    
    Parameters:
    
    expectedRows - the expected number of distinct row keys
    
    expectedCellsPerRow - the expected number of column key / value mappings in each row
    
    Throws:
    
    IllegalArgumentException - if expectedRows or expectedCellsPerRow is negative
  - create
```
public 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.
    
    Parameters:
    
    table - the table to copy
    
    Throws:
    
    NullPointerException - if any of the row keys, column keys, or values in table is null
  - contains
```
public boolean contains(Object rowKey,
                        Object columnKey)
```
    Description copied from interface: Table
    
    Returns true if the table contains a mapping with the specified row and column keys.
    
    Specified by:
    
    contains in interface Table<R,C,V>
    
    Parameters:
    
    rowKey - key of row to search for
    
    columnKey - key of column to search for
  - containsColumn
```
public boolean containsColumn(Object columnKey)
```
    Description copied from interface: Table
    
    Returns true if the table contains a mapping with the specified column.
    
    Specified by:
    
    containsColumn in interface Table<R,C,V>
    
    Parameters:
    
    columnKey - key of column to search for
  - containsRow
```
public boolean containsRow(Object rowKey)
```
    Description copied from interface: Table
    
    Returns true if the table contains a mapping with the specified row key.
    
    Specified by:
    
    containsRow in interface Table<R,C,V>
    
    Parameters:
    
    rowKey - key of row to search for
  - containsValue
```
public boolean containsValue(Object value)
```
    Description copied from interface: Table
    
    Returns true if the table contains a mapping with the specified value.
    
    Specified by:
    
    containsValue in interface Table<R,C,V>
    
    Parameters:
    
    value - value to search for
  - get
```
public V get(Object rowKey,
             Object columnKey)
```
    Description copied from interface: Table
    
    Returns the value corresponding to the given row and column keys, or null if no such mapping exists.
    
    Specified by:
    
    get in interface Table<R,C,V>
    
    Parameters:
    
    rowKey - key of row to search for
    
    columnKey - key of column to search for
  - equals
```
public boolean equals(Object obj)
```
    Description copied from interface: 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.
  - remove
```
public V remove(Object rowKey,
                Object columnKey)
```
    Description copied from interface: Table
    
    Removes the mapping, if any, associated with the given keys.
    
    Specified by:
    
    remove in interface Table<R,C,V>
    
    Parameters:
    
    rowKey - row key of mapping to be removed
    
    columnKey - column key of mapping to be removed
    
    Returns:
    
    the value previously associated with the keys, or null if no such value existed
  - isEmpty
```
public boolean isEmpty()
```
    Description copied from interface: Table
    
    Returns true if the table contains no mappings.
  - size
```
public int size()
```
    Description copied from interface: Table
    
    Returns the number of row key / column key / value mappings in the table.
  - clear
```
public void clear()
```
    Description copied from interface: Table
    
    Removes all mappings from the table.
  - put
```
public V put(R rowKey,
             C columnKey,
             V value)
```
    Description copied from interface: 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.
    
    Specified by:
    
    put in interface Table<R,C,V>
    
    Parameters:
    
    rowKey - row key that the value should be associated with
    
    columnKey - column key that the value should be associated with
    
    value - value to be associated with the specified keys
    
    Returns:
    
    the value previously associated with the keys, or null if no mapping existed for the keys
  - cellSet
```
public 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.
    
    Specified by:
    
    cellSet in interface Table<R,C,V>
    
    Returns:
    
    set of table cells consisting of row key / column key / value triplets
  - row
```
public Map<C,V> row(R rowKey)
```
    Description copied from interface: 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.
    
    Specified by:
    
    row in interface Table<R,C,V>
    
    Parameters:
    
    rowKey - key of row to search for in the table
    
    Returns:
    
    the corresponding map from column keys to values
  - column
```
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().
    
    Specified by:
    
    column in interface Table<R,C,V>
    
    Parameters:
    
    columnKey - key of column to search for in the table
    
    Returns:
    
    the corresponding map from row keys to values
  - rowKeySet
```
public Set<R> rowKeySet()
```
    Description copied from interface: 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.
    
    Specified by:
    
    rowKeySet in interface Table<R,C,V>
    
    Returns:
    
    set of row keys
  - columnKeySet
```
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.
    
    Specified by:
    
    columnKeySet in interface Table<R,C,V>
    
    Returns:
    
    set of column keys
  - values
```
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.
    
    Specified by:
    
    values in interface Table<R,C,V>
    
    Returns:
    
    collection of values
  - rowMap
```
public Map<R,Map<C,V>> rowMap()
```
    Description copied from interface: 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().
    
    Specified by:
    
    rowMap in interface Table<R,C,V>
    
    Returns:
    
    a map view from each row key to a secondary map from column keys to values
  - columnMap
```
public Map<C,Map<R,V>> columnMap()
```
    Description copied from interface: 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().
    
    Specified by:
    
    columnMap in interface Table<R,C,V>
    
    Returns:
    
    a map view from each column key to a secondary map from row keys to values
  - putAll
```
public void putAll(Table<? extends R,? extends C,? extends V> table)
```
    Description copied from interface: 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.
    
    Specified by:
    
    putAll in interface Table<R,C,V>
    
    Parameters:
    
    table - the table to add to this table
  - hashCode
```
public int hashCode()
```
    Description copied from interface: 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().
  - toString
```
public String toString()
```
    Returns the string representation rowMap().toString().

Class HashBasedTable<R,C,V>

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.common.collect.Table

Method Summary

Methods inherited from class java.lang.Object

Method Detail

create

create

create

contains

containsColumn

containsRow

containsValue

get

equals

remove

isEmpty

size

clear

put

cellSet

row

column

rowKeySet

columnKeySet

values

rowMap

columnMap

putAll

hashCode

toString