JAVA TreeSet TreeMap Queue Deque PriorityQueue

public static void main(String[] args) {

		List<Integer> list = Arrays.asList(45,23,12,88,5,16);
		NavigableSet<Integer> nset = new TreeSet<Integer>(list);
		System.out.println(nset);
		
		for(Iterator<Integer> itr  = nset.descendingIterator(); itr.hasNext();){
			System.out.print(itr.next()+"\t");
		}
		System.out.println();
		
		out.println(nset.first() + "\t" + nset.last());
		//---lower than 88 and most closed
		System.out.println(nset.lower(88));
		//--- <=
		System.out.println(nset.floor(88));
		//--- >
		System.out.println(nset.higher(56));
		//---- >=
		System.out.println(nset.ceiling(45));
		System.out.println("=============");
		
        NavigableMap<String, Integer> map = new TreeMap<String, Integer>();  
        
        map.put("56", 91);  
        map.put("8", 22);  
        map.put("86", 3);  
        map.put("22", 88); 
        
        out.println(map.ceilingKey("56"));
        out.println(map.ceilingEntry("56"));
        
        //-- others are similarity
        out.println(map.firstKey() + "\t" +map.firstEntry());
        
        out.println("Before pollFrist==>");
        out.println(map);
        map.pollFirstEntry();
        out.println("After==>"+map+"\n");
        
        //-----set
        out.println(nset);
        nset.pollFirst();
        out.println(nset+"\n"+"=====================");
        
        //---queue linkedlist 实现了 queue 和 list interface
        Queue<String> queue = new LinkedList<String>();
        queue.offer("star");
        queue.offer("tmac");
        queue.offer("kobe");
        out.println(queue.size()+"\t"+queue);
        //head element 
        out.println(queue.peek()+"\t"+queue);
        //get the head element and delete
        out.println(queue.poll()+"\t"+queue);
        //--note: 避免使用add remove elment 方法
        //----Deque 双端队列
        
        Deque<String> ld = new LinkedList<String>();
        Deque<Integer> ad = new ArrayDeque<Integer>();
        
        //---ld
        ld.offer("kobe");
        ld.offerFirst("frist");
        ld.offerLast("last");
        out.println(ld);
        ld.pollFirst();
        out.println(ld);
        out.println(ld.peekFirst());
        ld.removeFirstOccurrence("kobe");
        out.println(ld);
        
        //---------pirorityQueue
        PriorityQueue<GregorianCalendar> pq = new PriorityQueue<GregorianCalendar>();
        pq.offer(new GregorianCalendar(1906,Calendar.DECEMBER,9));
        pq.offer(new GregorianCalendar(1902,Calendar.JULY,9));
        pq.offer(new GregorianCalendar(1916,Calendar.DECEMBER,7));
        pq.offer(new GregorianCalendar(2206,Calendar.JUNE,9));
        
        for(GregorianCalendar date : pq){
        	out.println(date.get(Calendar.YEAR));
        }
        out.println("===========");
        while(!pq.isEmpty()){
        	out.println(pq.remove().get(Calendar.YEAR));
        }