Hash程式碼的實現

Employee實體類：

package com.test;

/**

* @author lizhangyu

* @date 2021/3/6 12:23

*/

public class Employee {

public int id;

public String name;

public Employee next;

public Employee(int id, String name) {

this.id = id;

this.name = name;

}

}

EmpLinkedList實體類

package com.test;

/**

* @author lizhangyu

* @date 2021/3/6 12:26

*/

public class EmpLinkedList {

private Employee head;

/**

* 新增

* @param employee

*/

public void add(Employee employee) {

if (head == null) {

head = employee;

return;

}

Employee cur = head;

while (true) {

if (cur.next == null) {

break;

}

cur = cur.next;

}

cur.next = employee;

}

/**

* 遍歷連結串列

* @param no

*/

public void list(int no) {

if (head == null) {

System.out.println("第" + (no + 1) + "條連結串列為空" );

return;

}

System.out.print("第" + (no + 1) + "條連結串列資訊為");

Employee cur = head;

while(true) {

System.out.printf("=> id=%d name=%s\t",cur.id, cur.name);

if (cur.next == null) {

break;

}

cur = cur.next;

}

System.out.println();

}

/**

* 查詢

* @param id

* @return

*/

public Employee find(int id) {

if (head == null) {

System.out.println("連結串列為空");

return null;

}

Employee cur = head;

while (true) {

if (cur.id == id) {

break;

}

if (cur.next == null) {

cur = null;

break;

}

cur = cur.next;

}

return cur;

}

}

HashTable實體類：

package com.test;

/**

* @author lizhangyu

* @date 2021/3/6 12:06

*/

public class HashTable {

private int size;

private EmpLinkedList[] empLinkedListArray;

public HashTable(int size) {

this.size = size;

this.empLinkedListArray = new EmpLinkedList[size];

//初始化連結串列

for (int i = 0; i < size ; i++) {

empLinkedListArray[i] = new EmpLinkedList();

}

}

/**

* 查詢

* @param id

*/

public void find(int id) {

int empLinkedListNO = hashFun(id);

Employee employee = empLinkedListArray[empLinkedListNO].find(id);

if (employee != null) {

System.out.printf("在第%d條連結串列中找到僱員id = %d\n", (empLinkedListNO + 1), id);

}else {

System.out.println("在雜湊表中中找到僱員");

}

}

/**

* 遍歷

*/

public void list() {

for (int i = 0; i < size; i++) {

empLinkedListArray[i].list(i);

}

}

/**

* 新增

* @param employee

*/

public void add(Employee employee) {

int employeeNo = hashFun(employee.id);

empLinkedListArray[employeeNo].add(employee);

}

/**

* 取模運算

* @param id

* @return

*/

public int hashFun(int id) {

return id % size;

}

}

HashTableDemo測試類

package com.test;

import java.util.Scanner;

/**

* @author lizhangyu

* @date 2021/3/6 12:45

*/

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: 新增僱員");

System.out.println("list: 顯示僱員");

System.out.println("find: 查詢僱員");

System.out.println("exit: 退出系統");

key = scanner.next();

switch (key) {

case "add" :

System.out.println("請輸入員工id");

int id = scanner.nextInt();

System.out.println("請輸入員工名字");

String name = scanner.next();

Employee employee = new Employee(id, name);

hashTable.add(employee);

break;

case "find" :

System.out.println("請輸入員工id");

id = scanner.nextInt();

hashTable.find(id);

break;

case "list" :

hashTable.list();

break;

case "exit" :

scanner.close();

System.exit(0);

default:

break;

}

}

}

}