java 单向链表和双向链表

java的单向链表~其实和c的链表思想差不多

package com.oracle.test;

import java.util.Iterator;

public class SingleLink implements Iterable{
        private int size;
        private Node first;//首节点
        /**
         * 
         * 节点内部类
         *
         */
        private class Node{
             Object data;
             Node next;
            public Node(Object data,Node next){
                this.data=data;
                this.next=next;
            }
        }
        /**
         * 根据指定索引查找节点
         * @param index
         * @return
         */
        private Node node(int index){
            Node c=first;
            for(int i=0;i<index;i++){
                c=c.next;
            }
            return c;
        }
        /**
         * 添加方法
         * @param obj
         */
        public void add(Object obj){
             Node newNode=new Node(obj,null);
             if(first==null){
                 first=newNode;
             }else{
                 Node last=node(size-1);
                 last.next=newNode;
             }
             size++;
        }
        public Object get(int index){
            this.checkIndex(index);
            return node(index).data;
        }
        public void del(int index){
            this.checkIndex(index);
            Node last=node(index-1);
            last.next=last.next=last.next.next;
            size--;
        }
        /**
         * 检查下标是否正确的方法
         * @param index
         */
        private void  checkIndex(int index){
            if(index<0){
                throw new IndexOutOfBoundsException("is negative number! "+index);
            }
            if(index>=size){
                throw new IndexOutOfBoundsException("index out of bounds "+index);
            }
        }
        /**
         * 返回大小的方法
         * @return
         */
        public int size(){
            return size;
        }

        private class Iter implements Iterator{
            private Node cNode=first;
            private int cursor=0;
            @Override
            public boolean hasNext() {
                return cursor!=size;
            }
            @Override
            public Object next() {
                Object o=cNode.data;
                cNode=cNode.next;
                cursor++;
                return o;
            }
        }
        @Override
        public Iterator iterator() {
            return new Iter() ;
        }
        /**
         * 在指定位置插入一个新的节点
         * @param obj
         */
        public void insert(Object obj,int index){
            this.checkIndex(index);
            if(index==0){
                Node newNode=new Node(obj,first);
                first=newNode;
            }else{
                Node target=node(index);
                Node newNode=new Node(obj,target);
                Node pre=node(index-1);
                pre.next=newNode;
            }
            size++;
        }
}

测试：

package com.oracle.test;

import java.util.Iterator;

public class TestLink {

    public static void main(String[] args) {
        SingleLink  sl=new SingleLink();
        sl.add("aa");
        sl.add("bb");
        sl.add("cc");
        for(int i=0;i<sl.size();i++){
            System.out.println(sl.get(i));
        }
        sl.insert("xxx",1);


        sl.del(2);
        //System.out.println(sl.get(2));
//      for(Object o:sl){
//          System.out.println(o);
//      }


        System.out.println("==========");
        Iterator  it=sl.iterator();
        while(it.hasNext()){
            System.out.println(it.next());
        }

        //System.out.println(sl.get(-100));
    }
}

运行截图：

其实双向链表没有改变都少，就是多加了一个向前的指针

package com.oracle.test;

import java.util.Iterator;

public class DoubleLink implements Iterable{
        private int size;
        private Node first;//首节点
        /**
         * 
         * 节点内部类
         *
         */
        private class Node{
             Object data;
             Node next;
             Node pre;
            public Node(Object data,Node next,Node pre){
                this.data=data;
                this.next=next;
                this.pre=pre;
            }
        }
        /**
         * 根据指定索引查找节点
         * @param index
         * @return
         */
        private Node node(int index){
            Node c=first;
            for(int i=0;i<index;i++){
                c=c.next;
            }
            return c;
        }
        /**
         * 添加方法
         * @param obj
         */
        public void add(Object obj){
             Node newNode=new Node(obj,null,null);
             if(first==null){
                 first=newNode;
             }else{
                 Node last=node(size-1);
                 newNode.pre=last;
                 newNode.next=last.next;
                 last.next=newNode;
             }
             size++;
        }
        public Object get(int index){
            this.checkIndex(index);
            return node(index).data;
        }
        public void del(int index){
            this.checkIndex(index);
            Node last=node(index-1);
            last.next=last.next.next;
            size--;
        }
        /**
         * 检查下标是否正确的方法
         * @param index
         */
        private void  checkIndex(int index){
            if(index<0){
                throw new IndexOutOfBoundsException("is negative number! "+index);
            }
            if(index>=size){
                throw new IndexOutOfBoundsException("index out of bounds "+index);
            }
        }
        /**
         * 返回大小的方法
         * @return
         */
        public int size(){
            return size;
        }

        private class Iter implements Iterator{
            private Node cNode=first;
            private int cursor=0;
            @Override
            public boolean hasNext() {
                return cursor!=size;
            }
            @Override
            public Object next() {
                Object o=cNode.data;
                cNode=cNode.next;
                cursor++;
                return o;
            }
        }
        @Override
        public Iterator iterator() {
            return new Iter() ;
        }
        /**
         * 在指定位置插入一个新的节点
         * @param obj
         */
        public void insert(Object obj,int index){
            this.checkIndex(index);
            if(index==0){
                Node newNode=new Node(obj,first,null);
                first=newNode;
            }else{
                Node target=node(index);
                Node newNode=new Node(obj,target,null);
                target.pre.next=newNode;
                newNode.pre=target.pre;
                target.pre=newNode;
            }
            size++;
        }
}

测试代码跟单向的都是一样，结果也是一样。