assertSame(Ordering.natural(), sortedTable.rowMap().comparator());

    sortedTable = TreeBasedTable.create(Collections.reverseOrder(), Ordering.usingToString());
    assertSame(Collections.reverseOrder(), sortedTable.rowMap().comparator());
  }

  public void testRowMapFirstKey() {
    sortedTable = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertSame("bar", sortedTable.rowMap().firstKey());
  }

    return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.
    ImmutableMap<R, ImmutableMap<C, V>> rowMap = this.rowMap;
    return ImmutableMap.<R, Map<C, V>>copyOf(rowMap);
  }

  @Override
  @CheckForNull
  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {

    return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.
    ImmutableMap<R, ImmutableMap<C, V>> rowMap = this.rowMap;
    return ImmutableMap.<R, Map<C, V>>copyOf(rowMap);
  }

  @Override
  @CheckForNull
  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {

      return super.put(key, value);
    }
  }

  // rowKeySet() and rowMap() are defined here so they appear in the Javadoc.

  @Override
  public SortedSet<R> rowKeySet() {
    return super.rowKeySet();
  }

  @Override
  public SortedMap<R, Map<C, V>> rowMap() {
    return super.rowMap();
  }

  /** Overridden column iterator to return columns values in globally sorted order. */

    }

    @Override
    public Map<R, Map<C, V2>> rowMap() {
      Function<Map<C, V1>, Map<C, V2>> rowFunction =
          new Function<Map<C, V1>, Map<C, V2>>() {
            @Override
            public Map<C, V2> apply(Map<C, V1> row) {
              return Maps.transformValues(row, function);
            }
          };
      return Maps.transformValues(fromTable.rowMap(), rowFunction);
    }

    @Override

    original.put(1, "foo", 'a');
    assertSame(original.columnKeySet(), transpose.rowKeySet());
    assertSame(original.rowKeySet(), transpose.columnKeySet());
    assertSame(original.columnMap(), transpose.rowMap());
    assertSame(original.rowMap(), transpose.columnMap());
    assertSame(original.values(), transpose.values());
    assertEquals(original.row(1), transpose.column(1));
    assertEquals(original.row(2), transpose.column(2));

  }

  @LazyInit @CheckForNull private transient RowMap rowMap;

  @Override
  public Map<R, Map<C, @Nullable V>> rowMap() {
    RowMap map = rowMap;
    return (map == null) ? rowMap = new RowMap() : map;
  }

  @WeakOuter
  private class RowMap extends ArrayMap<R, Map<C, @Nullable V>> {
    private RowMap() {
      super(rowKeyToIndex);
    }

    @Override

    public Set<R> rowKeySet() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.rowKeySet();
    }

    @Override
    public Map<R, Map<C, V>> rowMap() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.rowMap();
    }

    private static final long serialVersionUID = 0;
  }

  @Override
  protected Table<String, Integer, Character> create(@Nullable Object... data) {

    public Set<R> rowKeySet() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.rowKeySet();
    }

    @Override
    public Map<R, Map<C, V>> rowMap() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.rowMap();
    }

    private static final long serialVersionUID = 0;
  }

  @Override
  protected Table<String, Integer, Character> create(@Nullable Object... data) {

    Table<String, Integer, Character> table = HashBasedTable.create();
    table.put("foo", 1, 'a');
    table.put("bar", 1, 'b');
    table.put("foo", 3, 'c');
    return unmodifiableTable(table).rowMap();
  }