public int getColumnIndex(Comparable key) {
        // defer null argument check
        return this.data.getColumnIndex(key);
    }

    /**
     * Returns a column key.
     *
     * @param column  the column index (zero-based).
     *
     * @return The column key.
     */
    public Comparable getColumnKey(int column) {
        return this.data.getColumnKey(column);
    }

    /**
     * Returns the column keys.
     *
     * @return The keys.
     */
    public List getColumnKeys() {
        return this.data.getColumnKeys();
    }

    /**
     * Returns the row index for a given key.
     *
     * @param key  the row key (<code>null</code> not permitted).
     *
     * @return The row index.
     */
    public int getRowIndex(Comparable key) {
        // defer null argument check
        return this.data.getRowIndex(key);
    }

    /**
     * Returns a row key.
     *
     * @param row  the row index (zero-based).
     *
     * @return The row key.
     */
    public Comparable getRowKey(int row) {
        return this.data.getRowKey(row);
    }

    /**
     * Returns the row keys.
     *
     * @return The keys.
     */
    public List getRowKeys() {
        return this.data.getRowKeys();
    }

    /**
     * Returns the number of rows in the table.
     *
     * @return The row count.
     * 
     * @see #getColumnCount()
     */
    public int getRowCount() {
        return this.data.getRowCount();
    }

    /**
     * Returns the number of columns in the table.
     *
     * @return The column count.
     * 
     * @see #getRowCount()
     */
    public int getColumnCount() {
        return this.data.getColumnCount();