队列及循环队列（Java实现）

package ch03;

/*
 * 队列类
 */
public class MyQueue {
    // 底层实现是一个数组
    private long[] arr;
    // 有效数据大小
    private int elements;
    // 队头
    private int front;
    // 队尾
    private int end;

    /**
     * 默认构造方法
     */
    public MyQueue() {
        arr = new long[10];
        elements = 0;
        front = 0;
        end = -1;
    }

    /**
     * 带参数的构造方法，参数为数组的大小
     */
    public MyQueue(int maxsize) {
        arr = new long[maxsize];
        elements = 0;
        front = 0;
        end = -1;
    }

    /**
     * 添加数据，从队尾插入
     */
    public void insert(long value) {
        arr[++end] = value;
        elements++;
    }

    /**
     * 删除数据，从队头删除
     */
    public long remove() {
        elements--;
        return arr[front++];
    }

    /**
     * 查看数据，从队头查看
     */
    public long peek() {
        return arr[front];
    }

    /**
     * 判断是否为空
     */
    public boolean isEmpty() {
        return elements == 0;
    }

    /**
     * 判断是否满了
     */
    public boolean isFull() {
        return elements == arr.length;
    }
}

package ch03;

/*
 * 循环队列类
 */
public class MyCycleQueue {
    // 底层实现是一个数组
    private long[] arr;
    // 有效数据大小
    private int elements;
    // 队头
    private int front;
    // 队尾
    private int end;

    /**
     * 默认构造方法
     */
    public MyCycleQueue() {
        arr = new long[10];
        elements = 0;
        front = 0;
        end = -1;
    }

    /**
     * 带参数的构造方法，参数为数组的大小
     */
    public MyCycleQueue(int maxsize) {
        arr = new long[maxsize];
        elements = 0;
        front = 0;
        end = -1;
    }

    /**
     * 添加数据，从队尾插入
     */
    public void insert(long value) {
        if (end == arr.length - 1) {
            end = -1;
        }
        arr[++end] = value;
        elements++;
    }

    /**
     * 删除数据，从队头删除
     */
    public long remove() {
        long value = arr[front++];
        if (front == arr.length) {
            front = 0;
        }
        elements--;
        return value;
    }

    /**
     * 查看数据，从队头查看
     */
    public long peek() {
        return arr[front];
    }

    /**
     * 判断是否为空
     */
    public boolean isEmpty() {
        return elements == 0;
    }

    /**
     * 判断是否满了
     */
    public boolean isFull() {
        return elements == arr.length;
    }
}

package ch03;

public class TestMyQueue {
    public static void main(String[] args) {
        MyCycleQueue mq = new MyCycleQueue(4);
        mq.insert(23);
        mq.insert(45);
        mq.insert(13);
        mq.insert(1);

        System.out.println(mq.isFull());
        System.out.println(mq.isEmpty());

        System.out.println(mq.peek());
        System.out.println(mq.peek());

        while (!mq.isEmpty()) {
            System.out.print(mq.remove() + " ");
        }
        System.out.println();

        mq.insert(23);
        mq.insert(45);
        mq.insert(13);
        mq.insert(1);

        while (!mq.isEmpty()) {
            System.out.print(mq.remove() + " ");
        }
    }
}