Java实现单链表

简单实现带有头结点的单链表以及操作链表的基本方法

package 链表;

public class SingleLinkedListDemo {
    public static void main(String[] args) {
        SingleLinkedList singleLinkedList = new SingleLinkedList();
        singleLinkedList.add(2);
        singleLinkedList.add(3);
        singleLinkedList.add(1, 1);
        singleLinkedList.show();
        System.out.println("=========================");

        singleLinkedList.add(5, 3);
        singleLinkedList.add(4, 123);
        singleLinkedList.show();
        System.out.println("=========================");

        singleLinkedList.update(0, 3);
        singleLinkedList.show();
        System.out.println("=========================");

        singleLinkedList.delete(3);
        singleLinkedList.show();
        System.out.println("=========================");
    }
}


class SingleLinkedList {
    //初始化头结点，头结点val存放列表长度
    private final SingleLinkedListNode headNode = new SingleLinkedListNode(0);

    
    public void add(int val) {
        SingleLinkedListNode temp = headNode;
        while (temp.nextNode != null)
            temp = temp.nextNode;
        temp.nextNode = new SingleLinkedListNode(val);
        //插入节点后，链表长度+1
        headNode.val++;

    }

    
    public void add(int val, int loc) {
        SingleLinkedListNode temp = headNode;
        for (int i = 1; i < loc; i++) {
            if (temp.nextNode == null)
                break;
            temp = temp.nextNode;
        }
        SingleLinkedListNode newNode = new SingleLinkedListNode(val);
        newNode.nextNode = temp.nextNode;
        temp.nextNode = newNode;
        headNode.val++;
    }

    
    public void delete(int loc) {
        if (loc > headNode.val)
            throw new RuntimeException("超出链表长度");
        SingleLinkedListNode temp = headNode;
        for (int i = 1; i < loc; i++)
            temp = temp.nextNode;
        temp.nextNode = temp.nextNode.nextNode;
        headNode.val--;
    }

    
    public void update(int val, int loc) {
        if (loc > headNode.val)
            throw new RuntimeException("超出链表长度");
        SingleLinkedListNode temp = headNode.nextNode;
        for (int i = 1; i < loc; i++)
            temp = temp.nextNode;
        temp.val = val;

    }


    
    public void show() {
        if (headNode.nextNode == null) {
            System.out.println("链表为空！");
            return;
        }
        SingleLinkedListNode temp = headNode.nextNode;
        while (temp != null) {
            System.out.print(temp.val + "  ");
            temp = temp.nextNode;
        }
        System.out.println();
    }

}



class SingleLinkedListNode {
    public int val;
    public SingleLinkedListNode nextNode;

    public SingleLinkedListNode(int val) {
        this.val = val;
        this.nextNode = null;
    }

    @Override
    public String toString() {
        return "SingleLinkedListNode{" +
                "val=" + val +
                ", nextNode=" + nextNode +
                '}';
    }
}