Java数据结构——双端链表

//=================================================
// File Name       :	FirstLastList_demo
//------------------------------------------------------------------------------
// Author          :	Common

//类名：FirstLastList
//属性：
//方法：
class FirstLastList{
private Link first;
private Link last;

public FirstLastList() {			//构造函数
this.first = null;
this.last = null;
}

public boolean isEmpty(){
return (first == null);
}

public void insertFirst(int id,double dd){		//从链表的头开始插入
Link newLink = new Link(id,dd);
if(isEmpty()){
last = newLink;				//不用改变first
}
newLink.next = first;
first = newLink;
}

public void insertLast(int id,double dd){		//从链表的尾开始插入
Link newLink = new Link(id,dd);
if(isEmpty()){
first = newLink;			//不用改变last
}else{
last.next = newLink;		//在last后面添加新元素，并修改last的位置
}
last = newLink;						//注意：只有一个元素的时候，插入要把last也赋为newLink
}

public Link deleteFirst(){
Link temp = first;		//暂存first
if(first.next == null){		//如果只有一个元素，把last也赋为null
last = null;
}
first = first.next;			//把next设为first
return temp;				//返回原来的first
}

public void displayList(){
System.out.println("List(first-->last):");
Link current = first;			//用于不断改变位置实现遍历
while(current != null){
current.displayLink();
current = current.next;
}
}

}

//主类
//Function        : 	FirstLastList_demo
public class FirstLastList_demo {

public static void main(String[] args) {
// TODO 自动生成的方法存根
FirstLastList theList = new FirstLastList();
theList.insertFirst(11, 11.1);
theList.insertFirst(22, 22.2);
theList.insertFirst(33, 33.3);
theList.insertFirst(44, 44.4);
theList.insertFirst(55, 55.5);
theList.displayList();

theList.deleteFirst();
theList.deleteFirst();
theList.deleteFirst();
theList.displayList();

}

}