java开始到熟悉103-104

本次内容：linkedlist（）

此次是承接上次arraylist（），自己实现linkedlist（）（内容较少）

package list;
/**
 * 自定义linkedlist类
 * @author acer
 *
 */
public class mylinkedlist {
    private Node first;
    private Node last;
    private int size;
    public void add(Object obj)
    {
        Node n=new Node();
        if(first==null)
        {
            n.setPrevious(null);
            n.setObj(obj);
            n.setNext(null);
            first=n;
            last=n;
        }
        else
        {
            n.setPrevious(last);
            n.setObj(obj);
            n.setNext(null);
            last.setNext(n);
            last=n;
        }
        size++;
    }
    public void add(int index,Object obj)
    {
        Node temp=null;
        Node newNode=new Node();
        newNode.setObj(obj);
        if(first!=null)
        {
            temp=first;
            for(int i=0;i<index;i++)
            {
                temp=temp.getNext();
            }
        }
        newNode.setPrevious(temp.getPrevious());
        temp.getPrevious().setNext(newNode);
        newNode.setNext(temp);
        temp.setPrevious(newNode);
        size++;
        
    }
    public Object get(int index)
    {
        rangeCheck(index);
        Node temp=null;
        if(first!=null)
        {
            temp=first;
            for(int i=0;i<index;i++)
            {
                temp=temp.getNext();
            }
        }
        return temp.getObj();
    }
    public void removefirst()
    {
        Node temp=null;
        temp=first;
        temp=temp.getNext();
        temp.setPrevious(null);
        first.setNext(null);
        first=temp;
    }
    public void remove(int index)
    {
        rangeCheck(index);
        Node temp=null;
        if(first!=null)
        {
            temp=first;
            for(int i=0;i<index;i++)
            {
                temp=temp.getNext();
            }
        }
        if(temp!=null)
        {
            Node pre=temp.getPrevious();
            Node ne=temp.getNext();
            pre.setNext(ne);
            ne.setPrevious(pre);
            size--;
        }
        
    }
    public void rangeCheck(int index)
    {
        if(index<0||index>=size)
        {
            try {
                throw new Exception();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    public int size()
    {
        return size;
    }
    public static void main(String[] args)
    {
        mylinkedlist list=new mylinkedlist(); 
        list.add("aaa");
        list.add("bbb");
        list.add("ccc");
        list.add("ddd");
        System.out.println(list.size());
        System.out.println(list.get(1));
        list.removefirst();
        System.out.println(list.get(0));
    }
}


class Node
{
    private Node previous;
    private Object obj;
    private Node next;
    public Node()
    {
    }
    public Node(Node previous, Object obj, Node next) {
        super();
        this.previous = previous;
        this.obj = obj;
        this.next = next;
    }
    public Node getPrevious() {
        return previous;
    }
    public void setPrevious(Node previous) {
        this.previous = previous;
    }
    public Object getObj() {
        return obj;
    }
    public void setObj(Object obj) {
        this.obj = obj;
    }
    public Node getNext() {
        return next;
    }
    public void setNext(Node next) {
        this.next = next;
    }
}

运行结果：

4
bbb
bbb