哈希表

哈希表

public class HashTableDemo {
    public static void main(String[] args) {

        HashTable hashTable = new HashTable(7);

        String key = "";
        Scanner scanner = new Scanner(System.in);
        while (true){
            System.out.printf("add ：添加节点	");
            System.out.printf("list ：显示所有节点	");
            System.out.printf("find ：查找节点	");
            System.out.printf("del ：删除节点	");
            System.out.printf("exit ：退出程序
");

            key = scanner.next();
            switch (key){
                case "add" :
                    System.out.println("请输入id:");
                    int id = scanner.nextInt();
                    System.out.println("请输入name:");
                    String name = scanner.next();
                    Node node = new Node(id, name);
                    hashTable.add(node);
                    break;
                case "list" :
                    hashTable.list();
                    break;
                case "exit" :
                    scanner.close();
                    System.exit(0);
                case "find" :
                    System.out.print("请输入要查找的id:");
                    id = scanner.nextInt();
                    hashTable.findNode(id);
                    break;
                case "del" :
                    System.out.print("请输入要删除的id:");
                    id = scanner.nextInt();
                    hashTable.delNode(id);
                default:
                    break;
            }
        }
    }
}

class Node{
    public int id;
    public String name;
    public Node next;
    public Node(int id, String name) {
        this.id = id;
        this.name = name;
    }
}
class LinkedList{
    private Node head;
    //添加节点
    public void add(Node node){
        if (head == null){
            head = node;
            return;
        }
        //声明一个辅助指针，定位到最后
        Node temp = head;
        while (true){
            if (temp.next == null){
                break;
            }
            temp = temp.next;
        }
        temp.next = node;
    }
    //遍历链表
    public void list(int no){
        if (head == null){
            System.out.println("第"+no+"条链表为空！");
            return;
        }
        System.out.print("第"+no+"条链表信息为：");
        Node temp = head;
        while (true){
            System.out.printf("=> id =%d  name=%s	" , temp.id , temp.name);
            if (temp.next == null){
                break;
            }
            temp = temp.next;
        }
        System.out.println();
    }
    //查找
    public Node findNode(int id){
        if (head == null){
            System.out.println("链表为空");
            return null;
        }
        Node temp = head;
        while (true){
            if (temp.id == id){
                break;
            }
            if (temp.next == null){
                temp = null;//改变了最后一个数
                break;
            }
            temp = temp.next;
        }
        return temp;
    }
    //删除
    public void delNode(int id){
        if (head == null){
            System.out.println("链表为空,你要删除的节点不存在");
            return;
        }
        Node temp = head;
        while (true){
            if (head.id == id){
                head = head.next;
                System.out.println("删除成功");
                break;
            }
            if (temp.next == null){
                System.out.println("要删除的节点不存在");
                break;
            }
            if (temp.next.id == id){
                temp.next = temp.next.next;
                System.out.println("删除成功");
                break;
            }
            temp = temp.next;
        }


    }
}
//创建哈希表
class HashTable{
    private LinkedList[] linkedListsArr;
    private int size;//表示有多少条链表

    public HashTable(int size) {
        this.size = size;
        linkedListsArr = new LinkedList[size];
        for (int i = 0; i < size; i++) {
            linkedListsArr[i] = new LinkedList();
        }
    }

    //添加节点
    public void add(Node node){
        int linkListNo = hashFun(node.id);
        linkedListsArr[linkListNo].add(node);
    }
    //编写散列函数，取模法
    public int hashFun(int id){
        return id % size;
    }
    //遍历哈希表
    public void list(){
        for (int i = 0; i < size; i++) {
            linkedListsArr[i].list(i);
        }
    }
    //查找
    public void findNode(int id){
        int linkListNo = hashFun(id);
        Node node = linkedListsArr[linkListNo].findNode(id);
        if (node != null){
            System.out.println("在第"+(linkListNo+1)+"条链表找到该节点");
        }else {
            System.out.println("在哈希表中没有找到该节点");
        }
    }
    //删除节点
    public void delNode(int id){
        int linkListNo = hashFun(id);
        linkedListsArr[linkListNo].delNode(id);
    }
}