请问大家用java做注册账号demo时遇到的报错java.lang.NullPointerException

Question

这是我写的java注册账号的demo，输入各项信息后出现报错java.lang.NullPointerException。
经过简单的测试发现代码运行到 Test中的Integer count= UserService.register(user);，后面就报错了 请问这是什么情况导致的呢，应该怎么解决
下面是封装user用户的代码

public class user {
    /**
     * 用户类
     * @author chenzihan
     */

    private int userID ;         // id主键
    private String userAccount;  //用户账号
    private String userName;
    private String password;
    private String sex;          // 性别
    private String team;         // 阵营
    private String teamTribe;    // 部落
    private int money;           // 金币数
    private int thumbsUp ;       // 点赞数

    public int getUserID() {
        return userID;
    }

    public void setUserID(int userID) {
        this.userID = userID;
    }

    public String getUserAccount() {
        return userAccount;
    }

    public void setUserAccount(String userAccount) {
        this.userAccount = userAccount;
    }

    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 getSex() {
        return sex;
    }

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

    public String getTeam() {
        return team;
    }

    public void setTeam(String team) {
        this.team = team;
    }

    public String getTeamTribe() {
        return teamTribe;
    }

    public void setTeamTribe(String teamTribe) {
        this.teamTribe = teamTribe;
    }

    public int getMoney() {
        return money;
    }

    public void setMoney(int money) {
        this.money = money;
    }

    public int getThumbsUp() {
        return thumbsUp;
    }

    public void setThumbsUp(int thumbsUp) {
        this.thumbsUp = thumbsUp;
    }

}

下面是接口

public interface UserService {
    //注册新用户
    Integer register(user user)  throws SQLException;
    //登录已有账号
    Integer Login(user user);
}

下面是实现接口的类

```java
public class UserServiceImpl implements UserService {
    //获取Connection连接
    private Connection conn=jdbcUtil.getConnection();

    public UserServiceImpl() throws SQLException {
    }
    
    /*
        注册新用户
     */
    @Override
    public Integer register(user user) throws SQLException {
        String sql="insert into user" +
                "(userAccount,userName,Pword,sex,team,teamTribe,money,thumbsUp)" +
                "value (?,?,?,?,?,?,0,0)";
        PreparedStatement pstmt=conn.prepareStatement(sql);
        pstmt.setString(1,user.getUserAccount());
        pstmt.setString(2,user.getUserName());
        pstmt.setString(3,user.getPassword());
        pstmt.setString(4,user.getSex());
        pstmt.setString(5, user.getTeam());
        pstmt.setString(6,"暂未加入部落");

        int count=pstmt.executeUpdate();
        jdbcUtil.closeConnection(conn);
        jdbcUtil.closePreparedStatement(pstmt);
        return count;
    }

    @Override
    public Integer Login(user user) {
        return null;
    }
}

下面是测试类

            System.out.println("请输入账号：");
            String userAccount=in.next();

       System.out.println("请输入密码：");
        String password=in.next();
        user.setPassword(password);

        Integer count= UserService.register(user)；
        if(count==1){
            System.out.println("注册成功");
        }else{
            System.out.println("注册失败");
        }

下面是报错信息

Answer 1

Integer register(user user)，没觉得你的代码有什么问题吗？？？类名一般都是大写，你方法入参类名和实例名都一样，换成Integer register(User user)试试....