有序链表实现的优先级队列

package day1_29;

public class Link {

	public long dDate;
	public Link next;

	public Link(long dDate){
		this.dDate = dDate;
	}

	//打印链结点的方法
	public void displayLink(){

		System.out.println("["+dDate+"]");

	}

}
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package day1_29;

public class SortedList {

	private Link first;

	public SortedList(){
		first = null;
	}

	//判断链表是不是为空
	public boolean isEmpty(){
		if(first == null){
			return true;
		}else{
			return false;
		}
	}

	//插入一个元素的实现
	public void insert(long key){
		Link newLink = new Link(key);
		Link current = first;
		Link previous = null;
		while(current != null && key >current.dDate){
			previous = current;
			current = current.next;

		}
		if(previous == null){//在头节点的时候
			first = newLink;
		}else
			previous.next = newLink;

		newLink.next = current;

	}

	//删除节点的实现
	public Link remove(){//删除头结点的方法，只能删除头节点，为了符合队列的性质
		Link temp = first;
		first = first.next;
		return temp;

	}

	//打印链表的实现
	public void displayList(){

		Link current = first;
		while(current != null){

			current.displayLink();
			current = current.next;

		}
		System.out.println();

	}

}
================================================
package day1_29;

public class PriorityQ {

	private SortedList sortedList;

	public PriorityQ(){
		sortedList = new SortedList();

	}

	//队列的插入方法
	public void insert(long item){
		sortedList.insert(item);
	}

	//删除的方法
	public long remove(){

		return sortedList.remove().dDate;
	}

	//判断是不是为空
	public boolean isEmpty(){
		return sortedList.isEmpty();
	}

	//打印的方法
	public void display(){
		sortedList.displayList();
	}

}
==========================================
package day1_29;

public class Practice5_1 {

	/**
	 * 实现一个基于有序链表的优先级队列，队列的删除操作应该删除具有最小关键字
	 * 的链结点
	 */
	public static void main(String[] args) {
		PriorityQ priorityQ = new PriorityQ();
		priorityQ.insert(11);
		priorityQ.insert(33);
		priorityQ.insert(22);
		priorityQ.insert(55);
		priorityQ.insert(44);

		priorityQ.display();

	}

}