基本数据结构——队列

//定义一个数组来实现队列
public class Queue {
    private Object[] objs;
    private int head = 0;    //指向第一个元素
    private int tail = 0;    //指向新元素将要插入的位置
    
    public Queue() {
    }
    
    public Queue(int n) {
        objs = new Object[n];    //初始化数组大小
    }
    
    public boolean isEmpty() {　　
        if(tail == head) {
            return true;
        }
        else{
            return false;
        }
    }
    
    public boolean isFull() {
        if(head == 0 && tail == objs.length-1){
            return true;
        }
        if(head == tail+1){
            return true;
        }else{
            return false;
        }
    }
    
    public boolean enqueue(Object obj) {
        if(!isFull()) {
            objs[tail] = obj;
            if(tail == objs.length-1) {
                tail = 0;
            }else{
                tail += 1;                
            }
            return true;
        }else{
            return false;
        }
    }
    
    public Object dequeue() {
        if(isEmpty()) {
            return null;
        }else{
            Object o = objs[head];
            if(head == objs.length-1) {
                head = 0;
            }else{
                head = head+1;                
            }
            return o;
        }
    }
    
    public static void main(String[] args) {
        Queue q = new Queue(10);
        
        for(int i=0;i<11;i++) {
            if(q.enqueue(i)) {
                System.out.println(i);
            }
        }        
        System.out.println();
        for(int i=0;i<11;i++) {
            System.out.println(q.dequeue());
        }
    }
    
}