大家一起来做个小项目啊！求助！

刘一锋 · 刘一锋

import java.util.*;
class Employee
{ private String name;
private char sex;
private int birthday;
private String degree;
private String title;
private String address;
private String telephone;
public Employee(String name , char sex, int birthday, String degree, String title, String telephone)
{ this.name =name;
this.sex =sex;
this.birthday =birthday;
this.degree =degree;
this.title =title;
this.title =title;
this.telephone=telephone;
}
public Employee(String name)
{
this.name =name;
}
public void setName(String name)
{ this.name =name; }
public void setSex(char sex)
{ this.sex =sex; }
public void setBirthday(int birthday)
{this.birthday =birthday; }
public void setDegree(String degree)
{ this.degree =degree;}
public void setTitle(String title)
{ this.title =title;}
public void setAddress(String address, String title)
{ this.title =title;}
public void setTelephone(String telephone)
{ this.telephone=telephone;}
public String getName()
{
return name;
}
public char getSex()
{
return sex;
}
public int getBirthday()
{
return birthday;
}
public String getDegree()
{
return degree;
}
public String getTitle()
{
return title;
}
public String getAddress()
{
return address;
}
public String getTelephone()
{
return telephone;
}
}
class EmployManager
{
private static HashMap<String, Object> EmployeeListHT = new HashMap<String, Object>();
public static boolean putEmployee(String employee,Object obj)
{
EmployeeListHT.put( employee,obj);
return true;
}
public void putEmployee(Employee employee, Object object, int i, String string2, String string3, String string4, String string5, String string6) {
// TODO Auto-generated method stub
}
public Set<?> keySet() {
// TODO Auto-generated method stub
return null;
}
/* public static boolean removeEmployee(String name)
{
EmployeeListHT.remove(name);
return true;
}
public static Employee getEmployee(String name )
{
EmployeeListHT.get(name) ;
return Employee;
}*/
}
class CommandStage
{
public static void sop(Object obj)
{System.out.println(obj);}
@SuppressWarnings("unchecked")
public static void main(String[] srgs)
{
EmployManager em = new EmployManager();
em.putEmployee(new Employee("刘一锋"),1,22,"22","2","22","22","22");
Set<Employee> keySet = (Set<Employee>) em.keySet();
Iterator<Employee> it = keySet.iterator();
while(it.hasNext())
{
Employee emp =(Employee) it.next();
sop(emp);
}
}
}

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李印东老师

/*
职工管理系统
需求，实现对某单位职工信息的管理，包括职工信息的增加，删除，查询功能，
1，职工信息包括
private String name;姓名
private char sex;性别
private int birthday;出生年月
private String degree;学历
private String title;职务
private String address;地址
private String telephone;联系电话
2新增职工功能，键盘录入新职工信息
3，删除职工，输入职工姓名，将职工从列表中删除
4查询，输入姓名，显示该员工的信息
（菜鸟写了点，可是总报错，所以向大家求助，不用GUI,）
Y应该是创建三个类，一个是职工类，一个是职工管理类，另一个是控制台类包含主函数的，
职工信息储存室用哈希表的*/
import java.util.*;
class Employee {
private String name;
private char sex;
private int birthday;
private String degree;
private String title;
private String address;
private String telephone;

public void setName(String name)
{ this.name =name;}
public void setSex(char sex)
{ this.sex =sex; }
public void setBirthday(int birthday)
{this.birthday =birthday; }
public void setDegree(String degree)
{ this.degree =degree;}
public void setTitle(String title)
{ this.title =title;}
public void setAddress(String address)
{ this.address =address;}
public void setTelephone(String telephone)
{ this.telephone=telephone;}


public String getName()
{
return name;
}

public char getSex()
{
return sex;
}

public int getBirthday()
{
return birthday;
}
public String getDegree()
{
return degree;
}

public String getTitle()
{
return title;
}

public String getAddress()
{
return address;
}

public String getTelephone()
{
return telephone;
}
      }

class EmployManager //extends Employee
{
private static Hashtable EmployeeListHT = new Hashtable();

public static boolean addEmployee(Employee )
{
EmployeeListHT.add(Employee);
return true;
}

public static boolean addEmployee(String name)
{
EmployeeListHT.remove(neme);
return true;
}
public static Employee getEmployee(String name )
{
EmployeeListHT.get(neme) ;
return Employee;
}

}
public class CommandStage// extends EmployManager
{
public static void sop(Object obj)
{System.out.println(obj);}
public static void main(String[] srgs)
{
EmployManager em= new EmployManager();
em.addEmployee(Employee("刘一锋"));
sop(em);
}
}
//错误太多了，又不会做，愁思我了，

林国锋 · 林国锋

Student.java

package com.linguofeng.model;
import java.io.Serializable;
/**
* 学生类
*
* @author 林国锋
* @since 2011-9-23 {@link http://www.linguofeng.com}
*
*/
public class Student implements Serializable {
private static final long serialVersionUID = 1L;
private int id;// 学生编号
private String name;// 学生姓名
private String num;// 学生学号
private int sex;// 学生性别 1为男 0为女
public Student() {
}
public Student(int id, String name, String num, int sex) {
this.id = id;
this.name = name;
this.num = num;
this.sex = sex;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getNum() {
return num;
}
public void setNum(String num) {
this.num = num;
}
public int getSex() {
return sex;
}
public void setSex(int sex) {
this.sex = sex;
}
@Override
public String toString() {
return "Student:@id:" + this.id + "\t@name:" + this.name + "\t@num:"
+ this.num + "\t@sex:" + ((this.sex == 0) ? "女" : "男");
}
}

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StudentDao.java

package com.linguofeng.dao;
import java.util.TreeMap;
import com.linguofeng.model.Student;
/**
* 学生对象操作接口类
*
* @author 林国锋
* @since 2011-9-24 {@link http://www.linguofeng.com}
*
*/
public interface StudentDao {
/**
* 添加学生对象
*
* @param stuMap
* 学生对象集合
*/
public void addStu(TreeMap<String, Student> stuMap);
/**
* 更新学生对象
*
* @param stuMap
* 新的学生对象集合
*/
public void updateStu(TreeMap<String, Student> stuMap);
/**
* 查找所有学生对象
*
* @return 所有学生对象集合
*/
public TreeMap<String, Student> findAll();
/**
* 删除所有学生对象
*/
public void delAll();
/**
* 根据学生学号删除学生对象
*
* @param num
*/
public boolean delByNum(String num);
/**
* 根据学生学号查询学生对象信息
*
* @param num
* @return
*/
public Student findByNum(String num);
public void updateByNum(String num,Student student);
}

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StudentDao.java

package com.linguofeng.dao.impl;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Iterator;
import java.util.TreeMap;
import com.linguofeng.dao.StudentDao;
import com.linguofeng.model.Student;
/**
* 学生对象操作实现类
*
* @author 林国锋
* @since 2011-9-24 {@link http://www.linguofeng.com}
*
*/
public class StudentDaoImpl implements StudentDao {
private static final String file = "student.dat";
/**
* 添加学生
*/
@Override
public void addStu(TreeMap<String, Student> stuMap) {
/* 把原来的数据也加入去 */
Iterator<Student> iterator = findAll().values().iterator();
while (iterator.hasNext()) {
Student student = iterator.next();
stuMap.put(student.getNum(), student);
}
FileOutputStream fos = null;
ObjectOutputStream out = null;
try {
fos = new FileOutputStream(file);
out = new ObjectOutputStream(fos);
Iterator<Student> it = stuMap.values().iterator();
while (it.hasNext()) {
out.writeObject(it.next());
}
out.writeObject(null);
out.flush();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 查找所有学生对象
*/
@Override
public TreeMap<String, Student> findAll() {
FileInputStream fis = null;
ObjectInputStream in = null;
TreeMap<String, Student> stuMap = null;
try {
fis = new FileInputStream(file);
in = new ObjectInputStream(fis);
Student student = null;
stuMap = new TreeMap<String, Student>();
while ((student = (Student) (in.readObject())) != null) {
stuMap.put(student.getNum(), student);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return stuMap;
}
/**
* 删除所有学生对象
*/
@Override
public void delAll() {
FileOutputStream fos = null;
ObjectOutputStream out = null;
try {
fos = new FileOutputStream(file);
out = new ObjectOutputStream(fos);
out.writeObject(null);
out.flush();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 更新学生对象
*/
@Override
public void updateStu(TreeMap<String, Student> stuMap) {
FileOutputStream fos = null;
ObjectOutputStream out = null;
try {
fos = new FileOutputStream(file);
out = new ObjectOutputStream(fos);
Iterator<Student> it = stuMap.values().iterator();
while (it.hasNext()) {
out.writeObject(it.next());
}
out.writeObject(null);
out.flush();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public boolean delByNum(String num) {
boolean flag = false;
TreeMap<String, Student> stuMap = findAll();
if (stuMap.remove(num) != null) {
updateStu(stuMap);
flag = true;
}
return flag;
}
@Override
public Student findByNum(String num) {
return findAll().get(num);
}
@Override
public void updateByNum(String num, Student student) {
TreeMap<String, Student> stuMap = findAll();
stuMap.get(num).setId(student.getId());
stuMap.get(num).setName(student.getName());
stuMap.get(num).setNum(student.getNum());
stuMap.get(num).setSex(student.getSex());
updateStu(stuMap);
}
}

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林国锋 · 林国锋

StudentMain.java

package com.linguofeng.main;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Iterator;
import java.util.TreeMap;
import com.linguofeng.dao.StudentDao;
import com.linguofeng.dao.impl.StudentDaoImpl;
import com.linguofeng.model.Student;
public class StudentMain {
static StudentDao dao;
static BufferedReader br;
public static void main(String[] args) {
/* 启动时判断数据文件是否存在,如不存在则新建. */
File file = new File("student.dat");
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
dao = new StudentDaoImpl();
/* 获得控制台输入流 */
br = new BufferedReader(new InputStreamReader(System.in));
/* 进行死循环 */
while (true) {
System.out.println(getLine());
System.out.println("=[0]主菜单\t\t\t\t\t\t=");
System.out.println("=[1]查找学生\t\t\t\t\t\t=");
System.out.println("=[2]增加学生\t\t\t\t\t\t=");
System.out.println("=[3]删除一个学生\t\t\t\t\t=");
System.out.println("=[4]删除所有学生\t\t\t\t\t=");
System.out.println("=[5]学生列表\t\t\t\t\t\t=");
System.out.println("=[6]更新学生\t\t\t\t\t\t=");
System.out.println("=[x]退出\t\t\t\t\t\t=");
System.out.println(getLine());
System.out.print("请选择操作:");
/* 获得控制台输入的内容 */
String input = getInput();
if (input.equals("")) {
input = "x";
}
switch (input.charAt(0)) {
case '2' :
addStu();
break;
case 'x' :
System.out.println("退出成功,欢迎再次使用!");
System.exit(0);
break;
case '5' :
findAll();
break;
case '4' :
delAll();
break;
case '3' :
delByNum();
break;
case '1' :
findByNum();
break;
case '6' :
updateByNum();
break;
default :
System.out.println("不支持的系统指令,请重新输入!");
break;
}
}
}
/**
* 根据学生学号查询学生对象信息
*/
public static void findByNum() {
System.out.print("请输入要查询的学生学号:");
while (true) {
String input = getInput();
if (dao.findByNum(input) != null) {
System.out.println(dao.findByNum(input));
return;
} else if (input.equals("")) {
return;
} else {
System.out.print("查询失败,不存在该学生,请重新输入要删除的学生学号:");
}
}
}
/**
* 根据学生学号删除学生对象
*/
public static void delByNum() {
System.out.println(getLine());
findAll();/* 显示所有学生信息方便进行删除操作 */
System.out.println(getLine());
System.out.println("如需取消留空直接按回车.");
System.out.print("请输入要删除的学生学号:");
while (true) {
String input = getInput();
if (dao.delByNum(input)) {
System.out.println("删除成功!");
findAll();
return;
} else if (input.equals("")) {
return;
} else {
System.out.print("删除失败,不存在该学生,请重新输入要删除的学生学号:");
}
}
}
/**
* 学生列表
*/
public static void findAll() {
TreeMap<String, Student> stuMap = dao.findAll();
Iterator<Student> iterator = stuMap.values().iterator();
if (!iterator.hasNext()) {
System.out.println("数据库为空");
}
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
}
/**
* 删除所有学生对象
*/
public static void delAll() {
while (true) {
System.out.print("是否要删除所有学生信息,确定请输入YES,否请输入NO：");
String input = getInput();
if (input.equals("YES") || input.equals("yes")) {
dao.delAll();
System.out.println("清空成功");
return;
} else if (input.equals("NO") || input.equals("no")) {
return;
} else {
System.out.println("输入有误,请重新输入!");
}
}
}
/**
* 添加学生
*/
public static void addStu() {
while (true) {
System.out.print("请输入要添加学生的个数:");
String ch = null;
try {
ch = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}
if (ch.equals("")) {
System.out.println("输入有误,请重新输入!");
} else {
int size = Integer.parseInt(ch);
TreeMap<String, Student> stuMap = new TreeMap<String, Student>();
for (int i = 0; i < size; i++) {
Student student = new Student();
try {
System.out.print("请输入第 " + (i + 1) + " 个学生的姓名:");
student.setName(br.readLine());
System.out.print("请输入第 " + (i + 1) + " 个学生的学号:");
student.setNum(br.readLine());
System.out.print("请输入第 " + (i + 1)
+ " 个学生的性别(男输:1;女输:0):");
student.setSex(Integer.parseInt(br.readLine()));
} catch (IOException e) {
e.printStackTrace();
}
stuMap.put(student.getNum(), student);
}
dao.addStu(stuMap);
findAll();
return;
}
}
}

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由于字数限制，请接下面的代码。

林国锋 · 林国锋

public static void updateByNum() {
findAll();
System.out.print("请输入要修改的学生学号:");
while (true) {
String input = getInput();
String num = input;
Student student = dao.findByNum(num);
if (student != null) {
System.out.println(student);
System.out.println("如不修改直接留空按回车!");
System.out.print("请输入学生的新姓名:");
input = getInput();
if (!input.equals(""))
student.setName(input);
System.out.print("请输入学生的新学号:");
input = getInput();
if (!input.equals(""))
student.setNum(input);
System.out.print("请输入学生的新版性别(男输:1;女输:0):");
input = getInput();
if (!input.equals(""))
student.setSex(Integer.parseInt(input));
dao.updateByNum(num, student);
System.out.println("更新成功,更新后的数据:");
System.out.println(dao.findByNum(student.getNum()));
return;
} else if (input.equals("")) {
return;
} else {
System.out.print("查询失败,不存在该学生,请重新输入要修改的学生学号:");
}
}
}
public static void addTest() {
TreeMap<String, Student> stuMap = new TreeMap<String, Student>();
for (int i = 0; i < 10000; i++) {
Student student = new Student(i, "A" + i, "NUM" + i, 0);
stuMap.put(student.getNum(), student);
}
dao.addStu(stuMap);
return;
}
/**
* 获得===========分割符
*
* @return
*/
public static String getLine() {
return "=========================================================";
}
/**
* 获得控制台输入
*
* @return
*/
public static String getInput() {
String ch = "";
try {
ch = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}
return ch;
}
}

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这是我写的一个学生信息管理系统，使用的时候注意包路径和文件名，最好是导入到Eclipse工程中运行。

姚志华 · 姚志华

时间原因,不能给你写一个,但可以给你个相似的,你可以看下
USER类:
public class User {
private int  userid;
private String username;
private String password;

private String unum;

private String sex;

private String age;
private String tel;

private String purview;

private String address;

public int getUserid() {
return userid;
}

public void setUserid(int userid) {
this.userid = userid;
}

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public String getUnum() {
return unum;
}

public void setUnum(String unum) {
this.unum = unum;
}

public String getSex() {
return sex;
}

public void setSex(String sex) {
this.sex = sex;
}

public String getAge() {
return age;
}

public void setAge(String age) {
this.age = age;
}

public String getTel() {
return tel;
}

public void setTel(String tel) {
this.tel = tel;
}

public String getPurview() {
return purview;
}

public void setPurview(String purview) {
this.purview = purview;
}

public String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}
userdao接口:
public int updateUserByUserID(User user);
public int addUser(User user);
public User queryUserById(int  userid);
public int deleteUser(int id );
public List<User> queryAllUser(String username, int pageNumber, int pageSize);
public int queryAllUserCount(String username);
public int updatePassword(User user);实现类:public User loginUser(User user) {
PreparedStatement pstmt=null;
ResultSet rs=null;
String sql="select * from shop_user where username=? and password=?";
User users=new User();

try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
pstmt.setString(1,user.getUsername());
pstmt.setString(2, user.getPassword());
rs=pstmt.executeQuery();
if(rs.next()){

users.setUserid(rs.getInt("userid"));
users.setUsername(rs.getString("username"));
users.setPassword(rs.getString("password"));
users.setUnum(rs.getString("unum"));
users.setSex(rs.getString("sex"));
users.setAge(rs.getString("age"));
users.setTel(rs.getString("tel"));
users.setPurview(rs.getString("purview"));
users.setAddress(rs.getString("address"));
}else{
users = null;
}

} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
rs.close();

} catch (SQLException e) {

e.printStackTrace();
}
}

return users;
}
public int updateUserByUserID(User user) {
int rows=0;
PreparedStatement pstmt=null;
int i=0;
String sql="update shop_user set username=?,password=?,unum=?,sex=?,age=?,tel=?,purview=?,address=? where userid=?";
try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
pstmt.setString(++i, user.getUsername());
pstmt.setString(++i, user.getPassword());
pstmt.setString(++i, user.getUnum());
pstmt.setString(++i, user.getSex());
pstmt.setString(++i, user.getAge());
pstmt.setString(++i, user.getTel());
pstmt.setString(++i, user.getPurview());
pstmt.setString(++i, user.getAddress());
pstmt.setInt(++i, user.getUserid());
   rows=pstmt.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
} catch (SQLException e) {

e.printStackTrace();
}
}

return rows;
}

public int addUser(User user) {
PreparedStatement pstmt=null;
String sql="insert into shop_user values(SEQ_SHOP_USER_USERID.Nextval,?,?,?,?,?,?,?,?)";
int row=0;
int i=0;

try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
pstmt.setString(++i, user.getUsername());
pstmt.setString(++i, user.getPassword());
pstmt.setString(++i, user.getUnum());
pstmt.setString(++i, user.getSex());
pstmt.setString(++i, user.getAge());
pstmt.setString(++i, user.getTel());
pstmt.setString(++i, user.getPurview());
pstmt.setString(++i, user.getAddress());
row=pstmt.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
} catch (SQLException e) {

e.printStackTrace();
}
}

return row;
}

public User queryUserById(int  userid) {
PreparedStatement pstmt=null;
ResultSet rs=null;
String sql="select * from shop_user where userid=?";
User users=null;
int index=0;
users=new User();

try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
pstmt.setInt(++index,userid);
rs=pstmt.executeQuery();
while(rs.next()){

users.setUserid(rs.getInt("userid"));
users.setUsername(rs.getString("username"));
users.setPassword(rs.getString("password"));
users.setUnum(rs.getString("unum"));
users.setSex(rs.getString("sex"));
users.setAge(rs.getString("age"));
users.setTel(rs.getString("tel"));
users.setPurview(rs.getString("purview"));
users.setAddress(rs.getString("address"));
}

} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
rs.close();

} catch (SQLException e) {

e.printStackTrace();
}
}

return users;
}

public int deleteUser(int id) {
int row=0;
PreparedStatement pstmt=null;
int i=0;
String sql="delete shop_user where userid=?";
try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
pstmt.setInt(++i, id);
row=pstmt.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
} catch (SQLException e) {

e.printStackTrace();
}
}

return row;
}

public List<User> queryAllUser(String username, int pageNumber, int pageSize) {
List<User> list=new ArrayList<User>();
PreparedStatement pstmt=null;
ResultSet rs=null;
String sql="select t.* from(select a.*,rownum r from(select * from shop_user order by userid desc ) a where 1=1";
StringBuffer sb=new StringBuffer();
sb.append(sql);

if(username!=null){
sb.append(" and  username like '%");
sb.append(username);
sb.append("%')");
}else{
sb.append(")");
}
sb.append(" t where  r>=");
sb.append(pageSize*(pageNumber-1)+1);
sb.append(" and r<=");
sb.append(pageSize*pageNumber);

sql=sb.toString();

try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
rs=pstmt.executeQuery();
while(rs.next()){
               User user=new User();
               user.setUserid(rs.getInt("userid"));
     user.setUsername(rs.getString("username"));
     user.setPassword(rs.getString("password"));
     user.setUnum(rs.getString("unum"));
     user.setSex(rs.getString("sex"));
     user.setAge(rs.getString("age"));
     user.setTel(rs.getString("tel"));
     user.setPurview(rs.getString("purview"));
     user.setAddress(rs.getString("address"));
     list.add(user);
     }
} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
} catch (SQLException e) {

e.printStackTrace();
}
}

return list;
}

public int queryAllUserCount(String username) {
PreparedStatement pstmt=null;
ResultSet rs=null;
String sql="select count(userid) from shop_user where 1=1 ";
StringBuffer sb=new StringBuffer();
sb.append(sql);
if(username!=null){
sb.append("and username like '%");
      sb.append(username);
sb.append("%'");
}
sql=sb.toString();

int count=0;
try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
// if(username!=null){
// pstmt.setString(1,username) ;
// }else{
// pstmt.setString(1,null);
// System.out.println(sql);
// }

rs=pstmt.executeQuery();
while(rs.next()){
count=rs.getInt(1);
}
} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
} catch (SQLException e) {

e.printStackTrace();
}
}

return count;
}

public int updatePassword(User user) {
int row=0;
String sql="update shop_user set password=? where username=?";
PreparedStatement pstmt=null;
int i=0;

try {
pstmt=ConnectionManager.getConnection().prepareStatement(sql);
pstmt.setString(++i,user.getPassword());
pstmt.setString(++i,user.getUsername());
row=pstmt.executeUpdate();
} catch (SQLException e) {

e.printStackTrace();
}finally{
try {
pstmt.close();
} catch (SQLException e) {
e.printStackTrace();
}

}

return row;
}

我是从库里查的信息,库里只有一个USER表

刘一锋 · 刘一锋

感觉改代码真的好废时间啊，今天视频都还没看呢，愁

刘一锋 · 刘一锋

Exception in thread "main" java.lang.NullPointerException
at CommandStage.main(CommandStage.java:123)
编译没错误，运行出了NullPointerException
什么原因啊，搞不懂，

程钧杰 · 程钧杰

这个真不难，学了JDBC就可以做了，出现NullPointerException，我一般是再从数据库取东西的时候没放到变量里，好几次这种错误了

刘一锋 · 刘一锋

我知道这个是最基本的，但是对于初学者来说还是有点困难的，感觉，刚才看视频，发现不应该用HashMap应该用LIst，因为是一对多映射，一个名字对应着很多个信息

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