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.println("add:添加雇员");
            System.out.println("list:查看雇员");
            System.out.println("find:查找雇员");
            System.out.println("del:删除雇员");
            System.out.println("exit:退出");
                    
            key = scanner.next();
            switch (key) {
            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();
                
                Emp emp = new Emp(id, name);
                hashTable.add(emp);
                break;
            case "list":
                hashTable.list();
                break;
            case "find":
                System.out.println("请输入id:");
                int id2 = scanner.nextInt();
                hashTable.findEmpById(id2);
                break;
            case "del":
                System.out.println("请输入id:");
                int id3 = scanner.nextInt();
                hashTable.del(id3);
                break;
            case "exit":
                System.exit(10);
            default:
                break;
            }
        }
    }
}

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

// EmpLinkedList
class EmpLinkedList{
    // 头指针，执行第一个Emp，因此我们这个链表的head，是直接指向第一个Emp
    private Emp head;
    
    // id是自增长的
    public void add(Emp emp) {
        // 如果是添加一个雇员
        if(head == null) {
            head = emp;
            return;
        }
        // 如果不是第一个
        Emp curEmp = head;
        while(true) {
            if(curEmp.next == null) {
                break;
            }
            curEmp = curEmp.next;
        }
        curEmp.next = emp;
    }
    
    public void list(int no) {
        if(head == null) {
            System.out.println("第" + (no+1) +  "条链表为空！");
            return;
        }
        System.out.println("第" + (no+1) +  "条链表信息为：");
        Emp curEmp = head;
        while(true) {
            System.out.printf("=> id=%d name=%s\t",curEmp.id,curEmp.name);
            if(curEmp.next == null) {
                break;
            }
            curEmp = curEmp.next;
        }
        System.out.println();
    }
    
    // 根据id查找雇员
    public Emp findEmpByid(int id) {
        if(head == null) {
            System.out.println("链表为空");
            return null;
        }
        Emp curEmp = head;
        while(true) {
            if(curEmp.id == id) {
                break;
            }
            if(curEmp.next == null) {
                System.out.println("遍历完了，没有找到！");
                curEmp = null;
                break;
            }
            curEmp = curEmp.next;
        }
        return curEmp;
    }
    
    // 根据id进行删除
    public boolean del(int id) {
        boolean flag = false;
        if(head == null) {
            System.out.println("当前链表为空！");
            return flag;
        }
        if(head.id == id) {
            head = null;
            flag = true;
            return flag;
        }
        Emp curEmp = head;
        while(true) {
            // 找到了改雇员
            if(curEmp.next.id == id) {
                curEmp.next = curEmp.next.next;
                curEmp.next = null;
                return (flag == false);
            }
            // 没有找到
            if(curEmp.next == null) {
                System.out.println("没有找改雇员！");
                curEmp = null;
                return flag;
            }
            curEmp = curEmp.next;
        }
    }
}

// 哈希表
class HashTable{
    
    private EmpLinkedList[] empLinkedListArr;
    private int size;
    public HashTable(int size) {
        super();
        this.size = size;
        empLinkedListArr = new EmpLinkedList[size];
        
        for(int i = 0; i < size; i++){
            empLinkedListArr[i] = new EmpLinkedList();
        }
    }
    
    // 添加雇员
    public void add(Emp emp) {
        // 根据员工的id得到改员工应该添加到哪条链表
        int empLinkedListNo = hashFun(emp.id);
        // 将emp添加到对应的链表中
        empLinkedListArr[empLinkedListNo].add(emp);
    }
    
    public void list() {
        for (int i = 0; i < empLinkedListArr.length; i++) {
            empLinkedListArr[i].list(i);
        }
    }
    
    public void findEmpById(int id) {
        int empLinkedListNo = hashFun(id);
        Emp emp = empLinkedListArr[empLinkedListNo].findEmpByid(id);
        if(emp != null) {
            System.out.println("在第" + (empLinkedListNo+1) + "条链表中找到id = " + id + "雇员");
        } else {
            System.out.println("在哈希表中没有找到");
        }
    }
    
    public void del(int id) {
        int empLinkedListNo = hashFun(id);
        boolean flag = empLinkedListArr[empLinkedListNo].del(id);
        if(flag == true) {
            System.out.println("在第" + (empLinkedListNo+1) + "条链表中删除了id = " + id + "雇员");
        } else {
            System.out.println("在哈希表中没有找到");
        }
        
    }
    
    public int hashFun(int id) {
        return id %size;
    }
}