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HSQLDB example source code file (HsqlDeque.java)

This example HSQLDB source code file (HsqlDeque.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

baselist, default_initial_capacity, hsqldeque, hsqldeque, hsqllist, indexoutofboundsexception, indexoutofboundsexception, nosuchelementexception, nosuchelementexception, object, object, util

The HSQLDB HsqlDeque.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.lib;

import java.util.NoSuchElementException;

// fredt@users 20020130 - patch 1.7.0 by fredt - new class

/**
 * jdk 1.1 compatible minimal implementation of a list object suitable for
 * stack, queue and deque usage patterns backed by an Object[].
 * The memory footprint of the HsqlDeque doubles when it gets full
 * but does not shrink when it gets empty.
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version 1.9.0
 * @since 1.7.0
 */
public class HsqlDeque extends BaseList implements HsqlList {

    private Object[] list;
    private int      firstindex = 0;    // index of first list element
    private int      endindex   = 0;    // index of last list element + 1

    // can grow to fill list
    // if elementCount == 0 then firstindex == endindex
    private static final int DEFAULT_INITIAL_CAPACITY = 10;

    public HsqlDeque() {
        list = new Object[DEFAULT_INITIAL_CAPACITY];
    }

    public int size() {
        return elementCount;
    }

    public boolean isEmpty() {
        return elementCount == 0;
    }

    public Object getFirst() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        return list[firstindex];
    }

    public Object getLast() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        return list[endindex - 1];
    }

    public Object get(int i) throws IndexOutOfBoundsException {

        int index = getInternalIndex(i);

        return list[index];
    }

    public void add(int i, Object o) throws IndexOutOfBoundsException {
        throw new java.lang.RuntimeException();
    }

    public Object set(int i, Object o) throws IndexOutOfBoundsException {

        int    index  = getInternalIndex(i);
        Object result = list[index];

        list[index] = o;

        return result;
    }

    public Object removeFirst() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        Object o = list[firstindex];

        list[firstindex] = null;

        firstindex++;
        elementCount--;

        if (elementCount == 0) {
            firstindex = endindex = 0;
        } else if (firstindex == list.length) {
            firstindex = 0;
        }

        return o;
    }

    public Object removeLast() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        endindex--;

        Object o = list[endindex];

        list[endindex] = null;

        elementCount--;

        if (elementCount == 0) {
            firstindex = endindex = 0;
        } else if (endindex == 0) {
            endindex = list.length;
        }

        return o;
    }

/*
    public Object remove(int i){
        return get(i);
    }

    public void add(int i, Object o) {

    }
*/
    public boolean add(Object o) {

        resetCapacity();

        if (endindex == list.length) {
            endindex = 0;
        }

        list[endindex] = o;

        elementCount++;
        endindex++;

        return true;
    }

    public boolean addLast(Object o) {
        return add(o);
    }

    public boolean addFirst(Object o) {

        resetCapacity();

        firstindex--;

        if (firstindex < 0) {
            firstindex = list.length - 1;

            if (endindex == 0) {
                endindex = list.length;
            }
        }

        list[firstindex] = o;

        elementCount++;

        return true;
    }

    public void clear() {

        if (elementCount == 0) {
            return;
        }

        firstindex = endindex = elementCount = 0;

        for (int i = 0; i < list.length; i++) {
            list[i] = null;
        }
    }

    public int indexOf(Object value) {

        for (int i = 0; i < elementCount; i++) {
            int index = firstindex + i;

            if (index >= list.length) {
                index -= list.length;
            }

            if (list[index] == value) {
                return i;
            }
        }

        return -1;
    }

    public Object remove(int index) {

        int    target = getInternalIndex(index);
        Object value  = list[target];

        if (target == firstindex) {
            list[firstindex] = null;

            firstindex++;

            if (firstindex == list.length) {
                firstindex = 0;
            }
        } else if (target > firstindex) {
            System.arraycopy(list, firstindex, list, firstindex + 1,
                             target - firstindex);

            list[firstindex] = null;

            firstindex++;

            if (firstindex == list.length) {
                firstindex = 0;
            }
        } else {
            System.arraycopy(list, target + 1, list, target,
                             endindex - target - 1);

            endindex--;

            list[endindex] = null;

            if (endindex == 0) {
                endindex = list.length;
            }
        }

        elementCount--;

        if (elementCount == 0) {
            firstindex = endindex = 0;
        }

        return value;
    }

    private int getInternalIndex(int i) throws IndexOutOfBoundsException {

        if (i < 0 || i >= elementCount) {
            throw new IndexOutOfBoundsException();
        }

        int index = firstindex + i;

        if (index >= list.length) {
            index -= list.length;
        }

        return index;
    }

    private void resetCapacity() {

        if (elementCount < list.length) {
            return;
        }

        Object[] newList = new Object[list.length * 2];

        System.arraycopy(list, firstindex, newList, firstindex,
                         list.length - firstindex);

        if (endindex <= firstindex) {
            System.arraycopy(list, 0, newList, list.length, endindex);

            endindex = list.length + endindex;
        }

        list = newList;
    }

    public void toArray(Object[] array) {
        int tempCount = list.length - firstindex;

        if (tempCount > elementCount) {
            tempCount = elementCount;
        }

        System.arraycopy(list, firstindex, array, 0, tempCount);

        if (endindex <= firstindex) {
            System.arraycopy(list, 0, array, tempCount, endindex);

            endindex = list.length + endindex;
        }

    }
}

Other HSQLDB examples (source code examples)

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