雇员信息的增删改查

注意事项：给这个hash数组初始化的时候内外都要进行初始化
next和nextline的区别：next和nextline的注意事项

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

package com.hebut.liyiwei.hashTable;


import java.util.Scanner;

/**
 * @className: HashTableDemo
 * @author: Liyiwei
 * @date: 2024/10/26 下午4:04
 * @Version: 1.0
 * @description: 哈希表
 */

public class HashTableDemo {
    
    
    public static void main(String[] args) {
    
    
        HashTable hashTable = new HashTable(7);
        Scanner scanner = new Scanner(System.in);
        while (true) {
    
    
            System.out.println("add:增加雇员");
            System.out.println("getnamebyid:查找雇员");
            System.out.println("delnamebyid:删除雇员");
            System.out.println("list:遍历雇员");
            System.out.println("exit:退出程序");
            String input = scanner.next();
            switch (input) {
    
    
                case "add":
                    System.out.println("请输入id");
                    int id = scanner.nextInt();
                    System.out.println("请输入名字");
                    String name = scanner.next();
                    hashTable.add(new Emp(id,name));
                    break;
                case "getnamebyid":
                    System.out.println("请输入id");
                    int empid = scanner.nextInt();
                    String empName = hashTable.getEmpName(empid);
                    System.out.println(empName);
                    break;
                case "delnamebyid":
                    System.out.println("请输入id");
                    int delid = scanner.nextInt();
                    hashTable.delEmpName(delid);
                    break;
                case "list":
                    hashTable.display();
                    break;
                case "exit":
                    scanner.close();
                    System.exit(0);
            }
        }
    }
}
class HashTable {
    
    
    private EmpLinkedList[] empLinkedLists;
    public int size;
    public HashTable(int size) {
    
    
        empLinkedLists = new EmpLinkedList[size];
        this.size = size;
        for (int i = 0; i < empLinkedLists.length; i++) {
    
    
            empLinkedLists[i] = new EmpLinkedList();
        }
    }

    public void add(Emp emp) {
    
    
        int index = getHash(emp);
        empLinkedLists[index].addEmp(emp);
    }
    public void display() {
    
    
        for (int i = 0; i < empLinkedLists.length; i++) {
    
    
            if (empLinkedLists[i].getHead() == null) {
    
    
                System.out.print("第"+(i+1)+"条链表为空");
            }
            empLinkedLists[i].display();
            System.out.println();
        }
    }
    public int getHash(Emp emp) {
    
    
        int hash = emp.id % size;
        return hash;
    }
    public int getHash(int id) {
    
    
        int hash = id % size;
        return hash;
    }

    public String getEmpName(int id) {
    
    
        int index = getHash(id);
        Emp emp = empLinkedLists[index].getHead();
        if (emp == null) {
    
    
            return null;
        }
        return empLinkedLists[index].getEmp(id).getName();
    }

    public void delEmpName(int id) {
    
    
        int index = getHash(id);
        Emp emp = empLinkedLists[index].getHead();
        if (emp == null) {
    
    
            System.out.println("该人员不存在");
        }
        empLinkedLists[index].delEmp(id);
    }
}
class Emp{
    
    
    public int id;
    public String name;
    public Emp next;

    public Emp(int id, String name) {
    
    
        super();
        this.id = id;
        this.name = name;
    }

    public String getName() {
    
    
        return name;
    }
}

class EmpLinkedList{
    
    
    private Emp head;

    public void addEmp(Emp emp){
    
    
        if(head == null){
    
    
            head = emp;
        }else {
    
    
            Emp temp = head;
            while(temp.next != null){
    
    
                temp = temp.next;
            }
            temp.next = emp;
        }
    }
    public Emp getEmp(int id){
    
    
        Emp temp = head;
        while(temp != null){
    
    
            if(temp.id == id){
    
    
                return temp;
            }
        }
        return null;
    }
    public void delEmp(int id){
    
    
        Emp temp = head;
        if(temp.id == id){
    
    
            head = head.next;
        }
        while(temp.next != null){
    
    
            if(temp.next.id == id){
    
    
                temp.next = temp.next.next;
            }
        }
    }
    public void display(){
    
    
        Emp temp = head;
        while(temp != null){
    
    
            System.out.print("["+temp.id+","+temp.name+"] ");
            temp = temp.next;
        }
    }

    public Emp getHead() {
    
    
        return head;
    }
}