双向不带头不循环链表

//定义接口
public interface 双向不循环链表 {
//头插法
void addFirst(int data);
//尾插法
void addLast(int data);
//任意位置插入,第一个数据节点为0号下标
boolean addindex(int index,int data);
//查找是否包含关键字key是否在单链表当中
boolean contains(int key);
//删除第一次出现关键字为key的节点
int remove(int key);
//删除所有值为key的节点
void removeAllKey(int key);
//得到单链表的长度
int getLength();
void display();
void clear();
}
//接口的实现
public class DoubleLinkedListImpl implements IDoubleLinked {
class Node{
private int data;
private Node next;
private Node prev;
public Node(int data){
this.data=data;
this.next=null;
this.prev=null;
}
}
private Node head;
private Node last;
public DoubleLinkedListImpl(){
this.head=null;
this.last=null;
}
@Override
public void addFirst(int data) {
Node node=new Node ( data );
if(this.head==null){
this.head=node;
this.last=node;
}
else{
node.next=this.head;
this.head.prev=node;
this.head=node;
}
}

@Override
public void addLast(int data) {
    Node node=new Node(data);
    if(this.head==null){
        this.head=node;
        this.last=node;
    }
    else{
        this.last.next=node;
        node.prev=this.last;
        this.last=node;
    }

}
//判断index是否合法
private  void checkIndex(int index){
    if(index<0||index>getLength ()){
        throw new UnsupportedOperationException ("Index不合法！"  );
    }
}
private  Node searchIndex(int index){
    checkIndex ( index );
    Node cur=this.head;
    for(int count=0;count<index;++count){
        cur=cur.next;
    }
    return  cur;
}

@Override
public boolean addindex(int index, int data) {
    if(index==0){
        addFirst ( data );
        return true;
    }
    if(index==getLength ()){
        addLast ( data );
        return true;
    }
   Node  node=new Node ( data );
        Node cur=searchIndex ( index );
        node.next=cur;
        node.prev=cur.prev;
        node.next.prev=node;
        node.prev.next=node;
        return false;
}

@Override
public boolean contains(int key) {
    Node cur=this.head;
    while(cur!=null){
        if(cur.data==key){
            return  true;
        }
        cur=cur.next;
    }
    return false;
}

@Override
public int remove(int key) {
    Node cur = this.head;
    while (cur != null) {
        if (cur.data == key) {
            int oldData = cur.data;
            if (cur == this.head) {
                this.head = this.head.next;
                this.head.prev = null;
            } else {
                cur.prev.next = cur.next;
                if (cur.next == null) {
                    cur.next.prev = cur.prev;
                } else {
                    this.last = cur.prev;
                }
            }
            return oldData;

        }
        cur = cur.next;
    }
    return  -1;
}


@Override
public void removeAllKey(int key) {
    Node cur=this.head;

while(cur!=null){
if(cur.datakey){
if(curthis.head){
this.head=this.head.next;
this.head.prev=null;
}
else{
cur.prev.next=cur.next;
if(cur.next!=null){
cur.next.prev=cur.prev;
}
else{
this.last=cur.prev;
}
}
}
cur=cur.next;
}

}

@Override
public int getLength() {
    int count=0;
    Node cur=this.head;
    while(cur!=null){
       count++;
       cur=cur.next;
    }
    return count;


}

@Override
public void display() {
   Node cur=this.head;
   while(cur!=null){
       System.out.print (cur.data+" " );
      cur=cur.next;
   }
    System.out.println ( );

}

@Override
public void clear() {

while(this.head.next!=null){
Node cur=this.head.next;
this.head.next=cur.next;
cur.prev=null;
}
this.head=null;
this.last=null;
}
}
//测试
public class Test {
public static void main(String[] args) {
DoubleLinkedListImpl doubleLinked=new DoubleLinkedListImpl();
doubleLinked.addFirst ( 10 );
doubleLinked.addFirst ( 20 );
doubleLinked.addFirst ( 30 );
doubleLinked.addFirst ( 40 );
doubleLinked.addFirst ( 50 );
doubleLinked.addindex ( 0,60 );
doubleLinked.addLast ( 90 );
doubleLinked.addLast ( 100 );
doubleLinked.addLast ( 70 );
doubleLinked.addLast ( 60 );
doubleLinked.remove ( 4 );
doubleLinked.removeAllKey ( 2);
doubleLinked.display ();
System.out.println (doubleLinked.getLength ());

}

}