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HSQLDB example source code file (NumberSequence.java)

This example HSQLDB source code file (NumberSequence.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

hsqlname, hsqlname, integer, integer, long, numbersequence, numbersequence, object, object, string

The HSQLDB NumberSequence.java source code

/* Copyright (c) 2001-2008, 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.
 */


package org.hsqldb;

import org.hsqldb.HsqlNameManager.HsqlName;

/**
 * Maintains a sequence of numbers.
 *
 * @author  fredt@users
 * @since 1.7.2
 * @version 1.7.2
 */
public class NumberSequence {

    HsqlName name;

    // original start value - used in CREATE and ALTER commands
    private long startValue;

    // present value
    private long currValue;

    // last value
    private long lastValue;
    private long increment;
    private int  dataType;

    /**
     * constructor with initial value and increment;
     */
    public NumberSequence(HsqlName name, long value, long increment,
                          int type) {

        this.name      = name;
        startValue     = currValue = lastValue = value;
        this.increment = increment;
        dataType       = type;
    }

    /**
     * principal getter for the next sequence value
     */
    synchronized long getValue() {

        long value = currValue;

        currValue += increment;

        return value;
    }

    /**
     * getter for a given value
     */
    synchronized long getValue(long value) {

        if (value >= currValue) {
            currValue = value;
            currValue += increment;

            return value;
        } else {
            return value;
        }
    }

    /** @todo fredt - check against max value of type */
    Object getValueObject() {

        long value = currValue;

        currValue += increment;

        Object result;

        if (dataType == Types.INTEGER) {
            result = new Integer((int) value);
        } else {
            result = new Long(value);
        }

        return result;
    }

    /**
     * reset to start value
     */
    void reset() {

        // no change if called before getValue() or called twice
        lastValue = currValue = startValue;
    }

    /**
     * get next value without incrementing
     */
    public long peek() {
        return currValue;
    }

    /**
     * true if one or more values were retreived since the last resetWasUsed
     */
    boolean wasUsed() {
        return lastValue != currValue;
    }

    /**
     * reset the wasUsed flag
     */
    void resetWasUsed() {
        lastValue = currValue;
    }

    /**
     * reset to new initial value
     */
    public void reset(long value) {
        startValue = currValue = lastValue = value;
    }

    void reset(long value, long increment) {

        reset(value);

        this.increment = increment;
    }

    int getType() {
        return dataType;
    }

    public HsqlName getName() {
        return name;
    }

    public String getSchemaName() {
        return name.schema.name;
    }

    long getIncrement() {
        return increment;
    }
}

Other HSQLDB examples (source code examples)

Here is a short list of links related to this HSQLDB NumberSequence.java source code file:

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