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Java example source code file (TableModelComparator.java)

This example Java source code file (TableModelComparator.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

comparable, define, event, gui, jtable, object, swing, table, tablemodel, tablemodelcomparator, util

The TableModelComparator.java Java example source code

/*
 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.ui.table;

import java.util.*;

import javax.swing.table.TableModel;
import javax.swing.event.TableModelEvent;

/**
 * A comparator which compares rows in a table model
 */
public abstract class TableModelComparator implements Comparator {

    private boolean ascending;
    protected TableModel model;

    private int[] columns;

    public TableModelComparator(TableModel model) {
        this.model = model;

        // XXX - Should actually listen for column changes and resize
        columns = new int[model.getColumnCount()];
        columns[0] = -1;
    }

    /**
     * Add the column to the sort criteria
     */
    public void addColumn(int column) {
        // Shift columns in the array
        int[] tempArray = new int[model.getColumnCount()];
        System.arraycopy(columns, 1, tempArray, 0, columns.length - 1);

        columns = tempArray;
        columns[0] = column;
    }

    /**
     * Get the last column that was sorted
     */
    public int getColumn() {
        return columns[0];
    }

    public void setAscending(boolean ascending) {
        this.ascending = ascending;
    }

    public boolean isAscending() {
        return ascending;
    }

    /**
     * Implementation of the comparator method. A comparison is
     * made for rows.
     */
    public int compare(Object row1, Object row2) {
        for (int i = 0; i < columns.length; i++) {

            Object o1 = getValueForColumn(row1, columns[i]);
            Object o2 = getValueForColumn(row2, columns[i]);

            // If both values are null, return 0.
            if (o1 == null && o2 == null) {
                return 0;
            } else if (o1 == null) { // Define null less than everything.
                return -1;
            } else if (o2 == null) {
                return 1;
            }

            int result = 0;

            if (o1 instanceof Comparable) {
                Comparable c1 = (Comparable)o1;
                Comparable c2 = (Comparable)o2;

                result = c1.compareTo(c2);
            }

            // XXX Should have some sort of provision for determininte
            // if there is another way of comparing the objects.
            // Perhaps we should add the requirement that all table
            // values be Compabable.

            if (result != 0) {
                return ascending ? result : -result;
            }
        }
        return 0;
    }

    /**
     * Returns the value for the comparing object for the
     * column.
     *
     * @param obj Row object that was passed into Comparator.
     * @param column the column to retrieve
     */
    public abstract Object getValueForColumn(Object obj, int column);

}

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