src/java.desktop/share/classes/javax/swing/table/TableRowSorter.java

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 * particular file as subject to the "Classpath" exception as provided
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * accompanied this code).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package javax.swing.table;

import java.text.Collator;
import java.util.*;
import javax.swing.DefaultRowSorter;
import javax.swing.RowFilter;
import javax.swing.SortOrder;

/**
 * An implementation of <code>RowSorter</code> that provides sorting
 * and filtering using a <code>TableModel</code>.
 * The following example shows adding sorting to a <code>JTable</code>:
 * <pre>
 *   TableModel myModel = createMyTableModel();
 *   JTable table = new JTable(myModel);
 *   table.setRowSorter(new TableRowSorter(myModel));
 * </pre>
 * This will do all the wiring such that when the user does the appropriate
 * gesture, such as clicking on the column header, the table will
 * visually sort.
 * <p>
 * <code>JTable</code>'s row-based methods and <code>JTable</code>'s
 * selection model refer to the view and not the underlying
 * model. Therefore, it is necessary to convert between the two.  For
 * example, to get the selection in terms of <code>myModel</code>
 * you need to convert the indices:
 * <pre>
 *   int[] selection = table.getSelectedRows();
 *   for (int i = 0; i &lt; selection.length; i++) {
 *     selection[i] = table.convertRowIndexToModel(selection[i]);
 *   }
 * </pre>
 * Similarly to select a row in <code>JTable</code> based on
 * a coordinate from the underlying model do the inverse:
 * <pre>
 *   table.setRowSelectionInterval(table.convertRowIndexToView(row),
 *                                 table.convertRowIndexToView(row));
 * </pre>
 * <p>
 * The previous example assumes you have not enabled filtering.  If you
 * have enabled filtering <code>convertRowIndexToView</code> will return
 * -1 for locations that are not visible in the view.
 * <p>
 * <code>TableRowSorter</code> uses <code>Comparator</code>s for doing
 * comparisons. The following defines how a <code>Comparator</code> is
 * chosen for a column:
 * <ol>
 * <li>If a <code>Comparator</code> has been specified for the column by the
 *     <code>setComparator</code> method, use it.
 * <li>If the column class as returned by <code>getColumnClass</code> is
 *     <code>String</code>, use the <code>Comparator</code> returned by
 *     <code>Collator.getInstance()</code>.
 * <li>If the column class implements <code>Comparable</code>, use a
 *     <code>Comparator</code> that invokes the <code>compareTo</code>
 *     method.
 * <li>If a <code>TableStringConverter</code> has been specified, use it
 *     to convert the values to <code>String</code>s and then use the
 *     <code>Comparator</code> returned by <code>Collator.getInstance()</code>.
 * <li>Otherwise use the <code>Comparator</code> returned by
 *     <code>Collator.getInstance()</code> on the results from
 *     calling <code>toString</code> on the objects.
 * </ol>
 * <p>
 * In addition to sorting <code>TableRowSorter</code> provides the ability
 * to filter.  A filter is specified using the <code>setFilter</code>
 * method. The following example will only show rows containing the string
 * "foo":
 * <pre>
 *   TableModel myModel = createMyTableModel();
 *   TableRowSorter sorter = new TableRowSorter(myModel);
 *   sorter.setRowFilter(RowFilter.regexFilter(".*foo.*"));
 *   JTable table = new JTable(myModel);
 *   table.setRowSorter(sorter);
 * </pre>
 * <p>
 * If the underlying model structure changes (the
 * <code>modelStructureChanged</code> method is invoked) the following
 * are reset to their default values: <code>Comparator</code>s by
 * column, current sort order, and whether each column is sortable. The default
 * sort order is natural (the same as the model), and columns are
 * sortable by default.
 * <p>
 * <code>TableRowSorter</code> has one formal type parameter: the type
 * of the model.  Passing in a type that corresponds exactly to your
 * model allows you to filter based on your model without casting.
 * Refer to the documentation of <code>RowFilter</code> for an example
 * of this.
 * <p>
 * <b>WARNING:</b> <code>DefaultTableModel</code> returns a column
 * class of <code>Object</code>.  As such all comparisons will
 * be done using <code>toString</code>.  This may be unnecessarily
 * expensive.  If the column only contains one type of value, such as
 * an <code>Integer</code>, you should override <code>getColumnClass</code> and
 * return the appropriate <code>Class</code>.  This will dramatically
 * increase the performance of this class.
 *
 * @param <M> the type of the model, which must be an implementation of
 *            <code>TableModel</code>
 * @see javax.swing.JTable
 * @see javax.swing.RowFilter
 * @see javax.swing.table.DefaultTableModel
 * @see java.text.Collator
 * @see java.util.Comparator
 * @since 1.6
 */
public class TableRowSorter<M extends TableModel> extends DefaultRowSorter<M, Integer> {
    /**
     * Comparator that uses compareTo on the contents.
     */
    private static final Comparator<?> COMPARABLE_COMPARATOR =
            new ComparableComparator();

    /**
     * Underlying model.
     */
    private M tableModel;

    /**
     * For toString conversions.
     */
    private TableStringConverter stringConverter;


    /**
     * Creates a <code>TableRowSorter</code> with an empty model.
     */
    public TableRowSorter() {
        this(null);
    }

    /**
     * Creates a <code>TableRowSorter</code> using <code>model</code>
     * as the underlying <code>TableModel</code>.
     *
     * @param model the underlying <code>TableModel</code> to use,
     *        <code>null</code> is treated as an empty model
     */
    public TableRowSorter(M model) {
        setModel(model);
    }

    /**
     * Sets the <code>TableModel</code> to use as the underlying model
     * for this <code>TableRowSorter</code>.  A value of <code>null</code>
     * can be used to set an empty model.
     *
     * @param model the underlying model to use, or <code>null</code>
     */
    public void setModel(M model) {
        tableModel = model;
        setModelWrapper(new TableRowSorterModelWrapper());
    }

    /**
     * Sets the object responsible for converting values from the
     * model to strings.  If non-<code>null</code> this
     * is used to convert any object values, that do not have a
     * registered <code>Comparator</code>, to strings.
     *
     * @param stringConverter the object responsible for converting values
     *        from the model to strings
     */
    public void setStringConverter(TableStringConverter stringConverter) {
        this.stringConverter = stringConverter;
    }

    /**
     * Returns the object responsible for converting values from the
     * model to strings.
     *
     * @return object responsible for converting values to strings.
     */
    public TableStringConverter getStringConverter() {
        return stringConverter;
    }

    /**
     * Returns the <code>Comparator</code> for the specified
     * column.  If a <code>Comparator</code> has not been specified using
     * the <code>setComparator</code> method a <code>Comparator</code>
     * will be returned based on the column class
     * (<code>TableModel.getColumnClass</code>) of the specified column.
     * If the column class is <code>String</code>,
     * <code>Collator.getInstance</code> is returned.  If the
     * column class implements <code>Comparable</code> a private
     * <code>Comparator</code> is returned that invokes the
     * <code>compareTo</code> method.  Otherwise
     * <code>Collator.getInstance</code> is returned.
     *
     * @throws IndexOutOfBoundsException {@inheritDoc}
     */
    public Comparator<?> getComparator(int column) {
        Comparator<?> comparator = super.getComparator(column);
        if (comparator != null) {
            return comparator;
        }
        Class<?> columnClass = getModel().getColumnClass(column);
        if (columnClass == String.class) {
            return Collator.getInstance();
        }
        if (Comparable.class.isAssignableFrom(columnClass)) {
            return COMPARABLE_COMPARATOR;
        }
        return Collator.getInstance();
    }

    /**
     * {@inheritDoc}
     *
     * @throws IndexOutOfBoundsException {@inheritDoc}
     */
    protected boolean useToString(int column) {
        Comparator<?> comparator = super.getComparator(column);
        if (comparator != null) {
            return false;
        }
        Class<?> columnClass = getModel().getColumnClass(column);
        if (columnClass == String.class) {
            return false;
        }
        if (Comparable.class.isAssignableFrom(columnClass)) {
            return false;
        }
        return true;
    }

    /**
     * Implementation of DefaultRowSorter.ModelWrapper that delegates to a
     * TableModel.
     */
    private class TableRowSorterModelWrapper extends ModelWrapper<M,Integer> {
        public M getModel() {
            return tableModel;
        }

        public int getColumnCount() {
            return (tableModel == null) ? 0 : tableModel.getColumnCount();
        }

        public int getRowCount() {
            return (tableModel == null) ? 0 : tableModel.getRowCount();
        }

        public Object getValueAt(int row, int column) {
            return tableModel.getValueAt(row, column);
        }

        public String getStringValueAt(int row, int column) {
            TableStringConverter converter = getStringConverter();
            if (converter != null) {
                // Use the converter
                String value = converter.toString(
                        tableModel, row, column);
                if (value != null) {
                    return value;
                }
                return "";
            }

            // No converter, use getValueAt followed by toString
            Object o = getValueAt(row, column);
            if (o == null) {
                return "";
            }
            String string = o.toString();
            if (string == null) {
                return "";
            }
            return string;
        }

        public Integer getIdentifier(int index) {
            return index;
        }
    }


    private static class ComparableComparator implements Comparator<Object> {
        @SuppressWarnings("unchecked")
        public int compare(Object o1, Object o2) {
            return ((Comparable)o1).compareTo(o2);
        }
    }
}