fila.java

FTPCommand是一个在嵌入式环境（WindowsCE

package util;

public class Fila {
    
    public Node top;
    private Node tail;
    public int length;
    
    public Fila() {
        length = 0;
        top = null;
        tail = null;
    }
    
    public void enfileirar(Object object) {
        Node n = new Node(object, null);
        
        if (top != null) {
            Node t = tail;
            t.next = n;
            tail = n;
        } else top = tail = n;
        
        length++;
    }
    
    /**
     * @return null if queue is Empty;
     */
    
    public Object desenfileirar() {
        if (length == 0) return null;
        else if (length == 1) {
            Node t = top;
            top = tail = null;
            length--;
            
            return t.object;
        } else {
            Node t = top;
            top = t.next;
            length--;
            
            return t.object;
        }
    }
}

class Node {
    public Object object;
    public Node next;
    
    public Node(Object object, Node next) {
        this.object = object;
        this.next = next;
    }
}