自己实现的线性队列

package hjj.queue;

public class MyQueue<T> {
	private int size;
	private int capacity;
	private Object[] queue;
 	
	public MyQueue() {
		this(16);
		
	}
	public MyQueue(int capacity) {
		if(capacity < 0) {
			throw new RuntimeException("队列初始大小不能小于0");
		}
		this.capacity = capacity;
		queue = new Object[capacity];
	}
	
	public void extendsCapacity() {
		if(size == capacity) {
			Object[] newQueue = new Object[capacity * 2 + 1];
			
			for(int i=0; i<size; i++) {
				newQueue[i] = queue[i]; 
			}
			capacity = capacity * 2 + 1;
			queue = newQueue;
		}
	}
	public boolean enQueue(T obj) {
		extendsCapacity();
		queue[size] = obj;
		size++;
		return true;
	}
	
	public T quitQueue() {
		if(size == 0) {
			return null;
		}
		T obj = (T)queue[0];
		for(int i=0; i<size-1; i++) {
			queue[i] = queue[i+1];
		}
		queue[size-1] = null;
		size--;
		return obj;
	}
	
	public int indexOf(T obj) {
		for(int i=0; i<size; i++) {
			if(queue[i].equals(obj)) {
				return i;
			}
		}
		
		return -1;
	}
	
	public T get(int index) {
		if(index >= size) {
			return null;
		}
		
		return (T)queue[index];
	}
	public int size() {
		return size;
	}
	public int capacity() {
		return capacity;
	}
}