HSQLDB example source code file (Row.java)

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

Java - HSQLDB tags/keywords

cachedobject, hsqlexception, hsqlexception, intlookup, node, node, object, object, row, row

The HSQLDB Row.java source code

/*
 * For work developed by the HSQL Development Group:
 *
 * Copyright (c) 2001-2010, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 *
 * For work originally developed by the Hypersonic SQL Group:
 *
 * Copyright (c) 1995-2000, The Hypersonic SQL Group.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the Hypersonic SQL Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Hypersonic SQL Group.
 */


package org.hsqldb;

import org.hsqldb.lib.IntLookup;
import org.hsqldb.lib.java.JavaSystem;
import org.hsqldb.persist.CachedObject;
import org.hsqldb.rowio.RowOutputInterface;

// fredt@users 20020221 - patch 513005 by sqlbob@users (RMP)
// fredt@users 20020920 - patch 1.7.1 - refactoring to cut mamory footprint
// fredt@users 20021215 - doc 1.7.2 - javadoc comments

/**
 * Base class for a database row object implementing rows for
 * memory resident tables.<p>
 *
 * Subclass CachedRow implements rows for CACHED and TEXT tables
 *
 * @author Thomas Mueller (Hypersonic SQL Group)
 * @version 1.8.0
 * @since Hypersonic SQL
 */
public class Row implements CachedObject {

    int                tableId;
    int                iPos;
    protected Object[] oData;
    protected Node     nPrimaryNode;

    /**
     *  Default constructor used only in subclasses.
     */
    protected Row() {}

    /**
     *  Constructor for MEMORY table Row. The result is a Row with Nodes that
     *  are not yet linked with other Nodes in the AVL indexes.
     */
    Row(Table t, Object[] o) throws HsqlException {

        int index = t.getIndexCount();

        nPrimaryNode = Node.newNode(this, 0, t);

        Node n = nPrimaryNode;

        for (int i = 1; i < index; i++) {
            n.nNext = Node.newNode(this, i, t);
            n       = n.nNext;
        }

        tableId = t.getId();
        oData   = o;
    }

    /**
     * Returns the Node for a given Index, using the ordinal position of the
     * Index within the Table Object.
     */
    Node getNode(int index) {

        Node n = nPrimaryNode;

        while (index-- > 0) {
            n = n.nNext;
        }

        return n;
    }

    /**
     *  Returns the Node for the next Index on this database row, given the
     *  Node for any Index.
     */
    Node getNextNode(Node n) {

        if (n == null) {
            n = nPrimaryNode;
        } else {
            n = n.nNext;
        }

        return n;
    }

    /**
     * Returns the Row Object that currently represents the same database row.
     * In current implementations of Row, this is always the same as the this
     * Object for MEMORY tables, but could be a different Object for CachedRow
     * or CachedDataRow implementation. For example the Row Object that
     * represents a given database row can be freed from the Cache when other
     * rows need to be loaded into the Cache. getUpdatedRow() returns a
     * currently valid Row object that is in the Cache.
     */
    Row getUpdatedRow() throws HsqlException {
        return this;
    }

    /**
     * Returns the array of fields in the database row.
     */
    public Object[] getData() {
        return oData;
    }

    /**
     *  Is used only when the database row is deleted, not when it is freed
     *  from the Cache.
     */
    void delete() throws HsqlException {

        JavaSystem.memoryRecords++;

        nPrimaryNode = null;
    }

    void clearNodeLinks() {

        Node last;
        Node temp;

        last = nPrimaryNode;

        while (last.nNext != null) {
            temp       = last.nNext;
            last.nNext = null;
            last       = temp;
        }

        nPrimaryNode = null;
    }

    boolean isCascadeDeleted() {
        return nPrimaryNode == null;
    }

    public int getRealSize(RowOutputInterface out) {
        return 0;
    }

    public void setStorageSize(int size) {
        ;
    }

    public int getStorageSize() {
        return 0;
    }

    public long getId() {
        return ((long) tableId << 32) + ((long) iPos);
    }

    public static long getId(Table table, int pos) {
        return ((long) table.getId() << 32) + ((long) pos);
    }

    public int getPos() {
        return iPos;
    }

    public void setPos(int pos) {
        iPos = pos;
    }

    public boolean hasChanged() {
        return false;
    }

    public boolean isKeepInMemory() {
        return true;
    }

    public void keepInMemory(boolean keep) {}

    public boolean isInMemory() {
        return true;
    }

    public void setInMemory(boolean in) {}

    public void write(RowOutputInterface out) {}

    public void write(RowOutputInterface out, IntLookup lookup) {}

    /**
     * Lifetime scope of this method depends on the operations performed on
     * any cached tables since this row or the parameter were constructed.
     * If only deletes or only inserts have been performed, this method
     * remains valid. Otherwise it can return invalid results.
     *
     * @param obj row to compare
     * @return boolean
     */
    public boolean equals(Object obj) {

        if (obj == this) {
            return true;
        }

        if (obj instanceof Row) {
            return ((Row) obj).iPos == iPos;
        }

        return false;
    }

    /**
     * Hash code is valid only until a modification to the cache
     *
     * @return file position of row
     */
    public int hashCode() {
        return iPos;
    }
}