单链表的增删改查

/*
链表的增、改、查、删
 */

public class LinkLIST {
    int size;//节点个数
    NewNode head;//头节点地址
    class NewNode{
        int val;//存放具体数据
        NewNode next;//存下一个节点的地址
        public NewNode(int val){
            this.val=val;
        }
    }
    public void addFirst(int val){//头插
        NewNode node=new NewNode(val);
        if(head==null){
            head=node;
        }else {
           node.next=head;
           head=node;
        }size++;

    }
    public void addIndex(int index,int val){
        //在index位置插入值val
        if(index<0||index>size){
            System.out.println("illegal！！！");
            return;
        }else {
            NewNode node=new NewNode(val);
            NewNode temp=head;
                for (int i = 0; i < index - 1; i++) {
                    node.next=temp.next;
                    temp.next=node;

                    size++;

                }

            }
        }
        private boolean rangeCheck (int index){///改查删时使用的判断,是否合法
        if(index<0||index>=size){
            return false;
        }else {
            return true;
        }
        }
        public int get(int index){//查找index位置元素
        if(rangeCheck(index)==true){
            NewNode temp=head;
            for (int i=0;i<index;i++){
                temp=temp.next;

        }
            return temp.val;}
        else {
            System.out.println("illedgr!!!");
        } return -1;

    }
    public boolean contains(int val){//查是否含有值val
        for(NewNode temp=head;temp!=null;temp=temp.next){
            if(temp.val==val){
                return true;
            }
        }return false;

    }
    public int set(int index,int newVal){//改
        if(rangeCheck(index)==true){
            NewNode node=head;
            for (int i = 0; i < index; i++) {
                node=node.next;
            }
            int oldVal=node.val;
            node.val=newVal;
            return oldVal;
        }else {
            return -1;
        }
    }

    public String toString(){
        String ret=" ";
        NewNode prev=head;
        while (prev!=null){
            ret+= prev.val;
            ret+="-->";
            prev=prev.next;
        }
        ret+="NULL";
        return ret;
    }


}


public class Test2 {
    public static void main(String[] args) {
        LinkLIST a=new LinkLIST();
        a.addFirst(2);
        a.addFirst(3);
        a.addFirst(1);
        a.addFirst(5);
        System.out.println(a);
        a.addIndex(2,7);
        System.out.println(a);
        System.out.println(a.get(2));
        System.out.println(a.get(9));
        System.out.println("-----------------");
        System.out.println(a.contains(5));
        System.out.println(a.contains(15));
        System.out.println(a.set(3,666));
    }
}

输出结果：

删除操作后续在更新啦