weka.gui.JListHelper.java Source code

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Here is the source code for weka.gui.JListHelper.java

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/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * JListHelper.java
 * Copyright (C) 2005-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.gui;

import javax.swing.DefaultListModel;
import javax.swing.JList;

/**
 * A helper class for JList GUI elements with DefaultListModel or 
 * derived models.
 *
 * @author  FracPete (fracpete at waikato dot ac dot nz)
 * @version $Revision$
 * @see     JList
 * @see     DefaultListModel
 */
public class JListHelper {

    /** moves items up */
    public final static int MOVE_UP = 0;

    /** moves items down */
    public final static int MOVE_DOWN = 1;

    /**
     * moves the selected items by a certain amount of items in a given direction
     *
     * @param list        the JList to work on
     * @param moveby      the number of items to move by
     * @param direction   the direction to move in
     * @see               #MOVE_UP
     * @see               #MOVE_DOWN
     */
    protected static void moveItems(JList list, int moveby, int direction) {
        int[] indices;
        int i;
        Object o;
        DefaultListModel model;

        model = (DefaultListModel) list.getModel();

        switch (direction) {
        case MOVE_UP:
            indices = list.getSelectedIndices();
            for (i = 0; i < indices.length; i++) {
                if (indices[i] == 0)
                    continue;
                o = model.remove(indices[i]);
                indices[i] -= moveby;
                model.insertElementAt(o, indices[i]);
            }
            list.setSelectedIndices(indices);
            break;

        case MOVE_DOWN:
            indices = list.getSelectedIndices();
            for (i = indices.length - 1; i >= 0; i--) {
                if (indices[i] == model.getSize() - 1)
                    continue;
                o = model.remove(indices[i]);
                indices[i] += moveby;
                model.insertElementAt(o, indices[i]);
            }
            list.setSelectedIndices(indices);
            break;

        default:
            System.err.println(JListHelper.class.getName() + ": direction '" + direction + "' is unknown!");
        }
    }

    /**
     * moves the selected items up by 1
     *
     * @param list        the JList to work on
     */
    public static void moveUp(JList list) {
        if (canMoveUp(list))
            moveItems(list, 1, MOVE_UP);
    }

    /**
     * moves the selected item down by 1
     *
     * @param list        the JList to work on
     */
    public static void moveDown(JList list) {
        if (canMoveDown(list))
            moveItems(list, 1, MOVE_DOWN);
    }

    /**
     * moves the selected items to the top
     *
     * @param list        the JList to work on
     */
    public static void moveTop(JList list) {
        int[] indices;
        int diff;

        if (canMoveUp(list)) {
            indices = list.getSelectedIndices();
            diff = indices[0];
            moveItems(list, diff, MOVE_UP);
        }
    }

    /**
     * moves the selected items to the end
     *
     * @param list        the JList to work on
     */
    public static void moveBottom(JList list) {
        int[] indices;
        int diff;

        if (canMoveDown(list)) {
            indices = list.getSelectedIndices();
            diff = list.getModel().getSize() - 1 - indices[indices.length - 1];
            moveItems(list, diff, MOVE_DOWN);
        }
    }

    /**
     * checks whether the selected items can be moved up
     *
     * @param list        the JList to work on
     */
    public static boolean canMoveUp(JList list) {
        boolean result;
        int[] indices;

        result = false;

        indices = list.getSelectedIndices();
        if (indices.length > 0) {
            if (indices[0] > 0)
                result = true;
        }

        return result;
    }

    /**
     * checks whether the selected items can be moved down
     *
     * @param list        the JList to work on
     */
    public static boolean canMoveDown(JList list) {
        boolean result;
        int[] indices;

        result = false;

        indices = list.getSelectedIndices();
        if (indices.length > 0) {
            if (indices[indices.length - 1] < list.getModel().getSize() - 1)
                result = true;
        }

        return result;
    }
}