java 作业题7

没空敲了 代码是别人的轮子 稍微改了改

把单链表全实现了

package Test;


public class Linked <T>{
    
    private class Node{
        private T t;
        private Node next;
        public Node(T t,Node next){
            this.t = t;
            this.next = next;
        }
        public Node(T t){
            this(t,null);
        }
    }
    private Node head;            //头结点
    private int size;            //链表元素个数
    //构造函数
    public Linked(){
        this.head = null;
        this.size = 0;
    }
    
    //获取链表元素的个数
    public int getSize(){
        return this.size;
    }
    //判断链表是否为空
    public boolean isEmpty(){
        return this.size == 0;
    }
    //链表头部添加元素
    public void addFirst(T t){
        Node node = new Node(t);    //节点对象
        node.next = this.head;
        this.head = node;
        // this.head = new Node(e,head);等价上述代码
        this.size++;
    }
    //向链表尾部插入元素
    public void addLast(T t){
        this.add(t, this.size);
    }
    //向链表中间插入元素
    public void add(T t,int index){
        if (index <0 || index >size){
            throw new IllegalArgumentException("index is error");
        }
        if (index == 0){
            this.addFirst(t);
            return;
        }
        Node preNode = this.head;
        //找到要插入节点的前一个节点
        for(int i = 0; i < index-1; i++){
            preNode = preNode.next;
        }
        Node node = new Node(t);
        //要插入的节点的下一个节点指向preNode节点的下一个节点
        node.next = preNode.next;
        //preNode的下一个节点指向要插入节点node
        preNode.next = node;
        this.size++;
    }
    //删除链表元素
    public void remove(T t){
        if(head == null){
            System.out.println("无元素可删除");
            return;
        }
        //要删除的元素与头结点的元素相同
        while(head != null && head.t.equals(t)){
            head = head.next;
            this.size--;
        }
        /**
         * 上面已经对头节点判别是否要进行删除
         * 所以要对头结点的下一个结点进行判别
         */
        Node cur = this.head;
        while(cur != null && cur.next != null){
            if(cur.next.t.equals(t)){
                this.size--;
                cur.next = cur.next.next;
            }
            else cur = cur.next;
        }
        
    }
    //删除链表第一个元素
    public T removeFirst(){
        if(this.head == null){
            System.out.println("无元素可删除");
            return null;
        }
        Node delNode = this.head;
        this.head = this.head.next;
        delNode.next =null;
        this.size--;
        return delNode.t;
    }
    //删除链表的最后一个元素
    public T removeLast(){
        if(this.head == null){
            System.out.println("无元素可删除");
            return null;
        }
        //只有一个元素
        if(this.getSize() == 1){
            return this.removeFirst();
        }
        Node cur = this.head;    //记录当前结点
        Node pre = this.head;    //记录要删除结点的前一个结点
        while(cur.next != null){
            pre = cur;
            cur = cur.next;
        }
        pre.next = cur.next;
        this.size--;
        return cur.t;
    }
    //链表中是否包含某个元素
    public boolean contains(T t){
        Node cur = this.head;
        while(cur != null){
            if(cur.t.equals(t)){
                return true;
            }
            else cur = cur.next;
        }
        return false;
    }
    @Override
    public String toString() {
        StringBuffer sb = new StringBuffer();
        Node cur = this.head;
        while(cur != null){
            sb.append(cur.t+"->");
            cur = cur.next;
        }
        sb.append("NULL");
        return sb.toString();
    }
    
    public static void main(String[] args) 
    
    {
        Linked<Integer> linked = new Linked<Integer>();
        for(int i = 0; i < 10; i++){
            linked.addFirst(i);
            System.out.println(linked);
        }
        linked.addLast(33);
        linked.addFirst(33);
        linked.add(33, 5);
        System.out.println(linked);
        linked.remove(33);
        System.out.println(linked);
        System.out.println("删除第一个元素："+linked.removeFirst());
        System.out.println(linked);
        System.out.println("删除最后一个元素："+linked.removeLast());
        System.out.println(linked);
    }
}