數組實現隊列

import java.util.Arrays;/** * 用數組實現隊列 */@SuppressWarnings("unchecked")public class Queue<T> {private int DEFAULT_SIZE = 10;private int capacity;private Object[] elementData;private int front = 0;private int rear = 0;public Queue(){capacity = DEFAULT_SIZE;elementData = new Object[capacity];}public Queue(T element){this();elementData[0] = element;rear++;}public Queue(T element , int initSize){this.capacity = initSize;elementData = new Object[capacity];elementData[0] = element;rear++;}public int size(){return rear - front;}public void add(T element){if (rear > capacity - 1){throw new IndexOutOfBoundsException("the queue is full!");}elementData[rear++] = element;}    public T remove(){if (empty()){throw new IndexOutOfBoundsException("queue is empty");}T oldValue = (T)elementData[front];elementData[front++] = null; return oldValue;}    public T element() {          if (empty()){              throw new IndexOutOfBoundsException("queue is empty");          }          return (T)elementData[front];      }  public boolean empty(){return rear == front;}public void clear(){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();}}public static void main(String[] args){Queue<String> queue = new Queue<String>("ABs", 20);queue.add("DEF");queue.add("egg");//System.out.println(queue.empty());//System.out.println(queue.size());System.out.println(queue.element());//queue.clear();//System.out.println(queue.empty());//System.out.println(queue.size());}}