顺序队列的java实现

import java.util.Arrays;

public class SequenceQueue {
    private int DEFAULT_SIZE = 10;
    // 保存数组的长度。
    private int capacity;
    // 定义一个数组用于保存顺序队列的元素
    private Object[] elementData;
    // 保存顺序队列中元素的当前个数
    private int front = 0;
    private int rear = 0;

    // 以默认数组长度创建空顺序队列
    public SequenceQueue() {
        capacity = DEFAULT_SIZE;
        elementData = new Object[capacity];
    }

    // 以一个初始化元素来创建顺序队列
    public SequenceQueue(T element) {
        this();
        elementData[0] = element;
        rear++;
    }

    public SequenceQueue(T element, int initSize) {
        this.capacity = initSize;
        elementData = new Object[capacity];
        elementData[0] = element;
        rear++;
    }

    // 获取顺序队列的大小
    public int length() {
        return rear - front;
    }

    // 插入队列
    public void add(T element) {
        if (rear > capacity - 1) {
            throw new IndexOutOfBoundsException("队列已满的异常");
        }
        elementData[rear++] = element;
    }

    // 移除队列
    public T remove() {
        if (empty()) {
            throw new IndexOutOfBoundsException("空队列异常");
        }
        // 保留队列的rear端的元素的值
        T oldValue = (T) elementData[front];
        // 释放队列的rear端的元素
        elementData[front++] = null;
        return oldValue;
    }

    // 返回队列顶元素，但不删除队列顶元素
    public T element() {
        if (empty()) {
            throw new IndexOutOfBoundsException("空队列异常");
        }
        return (T) elementData[front];
    }

    // 判断顺序队列是否为空队列
    public boolean empty() {
        return rear == front;
    }

    // 清空顺序队列
    public void clear() {
        // 将底层数组所有元素赋为null
        Arrays.fill(elementData, null);
        front = 0;
        rear = 0;
    }

    public String toString() {
        if (empty()) {
            return "[]";
        } else {
            StringBuilder sb = new StringBuilder("[");
            for (int i = front; i < rear; i++) {
                sb.append(elementData[i].toString() + ", ");
            }
            int len = sb.length();
            return sb.delete(len - 2, len).append("]").toString();
        }
    }
}