org.tinygroup.queue.impl.QueueImpl Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of org.tinygroup.queue Show documentation
The newest version!
/**
 * Copyright (c) 2012-2016, www.tinygroup.org ([email protected]).
 *
 *  Licensed under the GPL, Version 3.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.gnu.org/licenses/gpl.html
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.tinygroup.queue.impl;

import org.tinygroup.commons.exceptions.NotExistException;
import org.tinygroup.queue.Queue;

/**
 * Created by IntelliJ IDEA. User: luoguo Date: 11-3-30 Time: 下午1:37 To change
 * this template use File | Settings | File Templates.
 */
public class QueueImpl implements Queue {

    private int maxSize;
    private E[] queueArray;
    private int offerPosition = 0;
    private int size = 0;
    private int pollPosition = 0;
    private String name;

    /**
     * 构造函数
     */
    public QueueImpl() {
        this(Queue.DEFAULT_QUEUE_SIZE);
    }

    /**
     * 构造函数
     *
     * @param name
     */
    public QueueImpl(String name) {
        this(name, Queue.DEFAULT_QUEUE_SIZE);
    }

    /**
     * 构造函数
     *
     * @param name
     * @param size
     */
    @SuppressWarnings("unchecked")
    public QueueImpl(String name, int size) {
        this.name = name;
        this.maxSize = size;
        queueArray = (E[]) (new Object[size]);
    }

    /**
     * 构造函数
     *
     * @param size
     */
    public QueueImpl(int size) {
        this(null, size);
    }

    /**
     * 添加元素到队列中
     *
     * @param o
     * @return boolean
     */
    public void offer(E o) {
        synchronized (queueArray) {
            if (size >= maxSize) {
                throw new RuntimeException("优先队列已满！");
            } else {
                queueArray[offerPosition++] = o;
                if (offerPosition == maxSize) {
                    offerPosition = 0;
                }
                size++;
            }
        }
    }

    /**
     * 元素出队，并删除 返回所删除的元素
     *
     * @return E
     */
    public E poll() {
        synchronized (queueArray) {
            if (size == 0) {
                throw new RuntimeException("队列为空！");
            } else {
                E e = queueArray[pollPosition];
                queueArray[pollPosition] = null;
                pollPosition++;
                if (pollPosition == maxSize) {
                    pollPosition = 0;
                }
                size--;
                return e;
            }
        }
    }

    /**
     * 元素出队，并删除 返回所删除的元素
     *
     * @return E
     */
    public E remove() {
        synchronized (queueArray) {
            if (size == 0) {
                throw new NotExistException();
            } else {
                E e = queueArray[pollPosition];
                queueArray[pollPosition] = null;
                pollPosition++;
                if (pollPosition == maxSize) {
                    pollPosition = 0;
                }
                size--;
                return e;
            }
        }
    }

    /**
     * 获取队列头元素
     *
     * @return E
     */
    public E peek() {
        synchronized (queueArray) {
            if (maxSize == 0) {
                throw new RuntimeException("队列为空！");
            } else {
                return queueArray[pollPosition];
            }
        }
    }

    /**
     * 获取队列头元素
     *
     * @return E
     */
    public E element() {
        synchronized (queueArray) {
            if (isEmpty()) {
                throw new NotExistException();
            } else {
                return queueArray[pollPosition];
            }
        }
    }

    /**
     * 检查队列是否为空
     */
    public boolean isEmpty() {
        synchronized (queueArray) {
            return size == 0;
        }
    }

    /**
     * 检查队列是否为满
     */
    public boolean isFull() {
        synchronized (queueArray) {
            return size == maxSize;
        }
    }

    /**
     * 获取队列名称
     *
     * @return String
     */
    public String getName() {
        if (name != null) {
            return name;
        } else {
            return this.getClass().getSimpleName();
        }
    }

    /**
     * 设置队列名称
     *
     * @param name
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * 获取队列长度
     *
     * @return int
     */
    public int getSize() {
        return maxSize;
    }

    /**
     * 获取已用队列长度
     *
     * @return int
     */
    public int getUsingSize() {
        synchronized (queueArray) {
            return size;
        }
    }

    /**
     * 获取空闲队列长度
     *
     * @return int
     */
    public int getIdleSize() {
        synchronized (queueArray) {
            return maxSize - size;
        }
    }

    public int size() {
        return size;
    }
}