"insert into user values(?,?,?,?)";
如果我这句的第一个问号是ID 在数据库端设置成了 主键而且是自增的
我在JDBC中如何来写的 还需要不需要写这个参数 如果不需要我怎么解决这个第一个问号。

public void insertUser(User user) throws SQLException {
String sql1 = "insert into user values(?,?,?,?)";
ps = con.prepareStatement(sql1);
user.setId(sum("user")+1);
ps.setInt(1, user.getId());
ps.setString(2, user.getPassword());
ps.setString(3, user.getName());
ps.setString(4, user.getActor());
ps.executeUpdate();

String sql2 = "insert into droit values(?,?)";
PreparedStatement ps1 = con.prepareStatement(sql2);
HashSet<Droit> ls = user.getDroits();
Integer j = sum("droit");
for (Iterator<Droit> it = ls.iterator(); it.hasNext();) {
Droit droit = it.next();
droit.setId(++j);
ps1.setInt(1, droit.getId());
ps1.setString(2, droit.getName());
ps1.executeUpdate();
}

String sql3 = "insert into u_d values(?,?)";
PreparedStatement ps2 = con.prepareStatement(sql3);
ps2.setInt(1, user.getId());
HashSet<Droit> dt = user.getDroits();
for (Iterator<Droit> tt = dt.iterator(); tt.hasNext();) {
Droit droit = tt.next();
ps1.setInt(2, droit.getId());
ps1.executeUpdate();
}

}
这个方法为什么总是抛
Parameter index out of range (1 > number of parameters, which is 0).
这个异常啊

private Integer sum(String table) {
String sql = "select max(id) from " + table;
try {
ps = con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
while (rs.next()){
System.out.println(rs.getInt(1));
return rs.getInt(1);}
} catch (SQLException e) {
e.printStackTrace();
return 0;
}
return 0;

}

先解决你第一个问题``
你的ID是自动生成的话，就把那个问号去掉就可以了，不需要管它

你第二个问题
你用输出语句确定一下，是哪一句报的错`
这样看很郁闷````

package com.chen.dao.jdbc;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import com.chen.factory.ConnectionFactory;
import com.chen.pojo.Droit;
import com.chen.pojo.User;
public class UserDao {
    private Connection con;
    private PreparedStatement ps;
    public UserDao() {
        con = ConnectionFactory.getConnection();
    }
    public void deleteUser(Integer id) throws SQLException {
        String sql1 = \"delete from user where id = ?\";
        String sql2 = \"delete from u_d where user_id = ?\";
        ps = con.prepareStatement(sql1);
        ps.setInt(1, id);
        ps.executeUpdate();
        ps = con.prepareStatement(sql2);
        ps.setInt(1, id);
        ps.executeUpdate();
    }
    public User findUserById(Integer id) throws SQLException {
        String sql = \"select user.id,user.name,user.password,user.actor,droit.name \"
                + \"from user,u_d,droit \"
                + \"where user.id=u_d.user_id and droit.id=u_d.droit_id and user.id = ?\";
        ps = con.prepareStatement(sql);
        ps.setInt(1, id);
        ResultSet result = ps.executeQuery();
        User user = new User();
        HashSet<Droit> set = new HashSet<Droit>();
        while (result.next()) {
            user.setId(Integer.parseInt(result.getString(1)));
            user.setName(result.getString(2));
            user.setPassword(result.getString(3));
            user.setActor(result.getString(4));
            Droit droit = new Droit();
            droit.setName(result.getString(5));
            set.add(droit);
        }
        user.setDroits(set);
        return user;
    }
    public User findByName(String name, String psw) throws SQLException {
        String sql = \"select user.id,user.name,user.password,user.actor,droit.name \"
                + \"from user,u_d,droit where user.id=u_d.user_id and \"
                + \"droit.id=u_d.droit_id and user.name = ? and user.password = ?\";
        ps = con.prepareStatement(sql);
        ps.setString(1, name);
        ps.setString(2, psw);
        ResultSet result = ps.executeQuery();
        User user = new User();
        HashSet<Droit> set = new HashSet<Droit>();
        while (result.next()) {
            user.setId(Integer.parseInt(result.getString(1)));
            user.setName(result.getString(2));
            user.setPassword(result.getString(3));
            user.setActor(result.getString(4));
            Droit droit = new Droit();
            droit.setName(result.getString(5));
            set.add(droit);
        }
        user.setDroits(set);
        return user;
    }
    public HashSet findUserByAll() throws SQLException {
        String sql1 = \"select user.id,user.name,user.password,user.actor from user \";
        String sql2 = \"select droit.id,droit.name from u_d,user,droit \"
                + \" where u_d.droit_id=droit.id and u_d.user_id = ?\";
        HashSet<User> users = new HashSet<User>();
        ps = con.prepareStatement(sql1);
        ResultSet rs1 = ps.executeQuery();
        while (rs1.next()) {
            User user = new User();
            user.setId(Integer.parseInt(rs1.getString(1)));
            user.setName(rs1.getString(2));
            user.setPassword(rs1.getString(3));
            user.setActor(rs1.getString(4));
            ps = con.prepareStatement(sql2);
            ps.setLong(1, user.getId());
            ResultSet rs2 = ps.executeQuery();
            HashSet droits = new HashSet();
            while (rs2.next()) {
                Droit droit = new Droit();
                droit.setId(rs2.getInt(1));
                droit.setName(rs2.getString(2));
                droits.add(droit);
            }
            user.setDroits(droits);
            users.add(user);
        }
        return users;
    }
    public void addUser(User user) throws SQLException {
        String sql1 = \"insert into user values(?,?,?,?)\";
        ps = con.prepareStatement(sql1);
        user.setId(sum(\"user\")+1);
        System.out.println(user.getId());
        ps.setInt(1, user.getId());
        ps.setString(2, user.getPassword());
        ps.setString(3, user.getName());
        ps.setString(4, user.getActor());
        ps.executeUpdate();
        String sql2 = \"insert into droit values(?,?)\";
        PreparedStatement ps1 = con.prepareStatement(sql2);
        HashSet<Droit> ls = user.getDroits();
        Integer j = sum(\"droit\");
        for (Iterator<Droit> it = ls.iterator(); it.hasNext();) {
            Droit droit = it.next();
            droit.setId(++j);
            ps1.setInt(1, droit.getId());
            ps1.setString(2, droit.getName());
            ps1.executeUpdate();
        }
         String sql3 = \"insert into u_d values(?,?)\";
         PreparedStatement ps2 = con.prepareStatement(sql3);
         ps2.setInt(1, user.getId());
         HashSet<Droit> dt = user.getDroits();
            for (Iterator<Droit> tt = dt.iterator(); tt.hasNext();) {
                Droit droit = tt.next();
                ps2.setInt(2, droit.getId());
                ps2.executeUpdate();
            }
        
    }
    public void modifyUser(User user) throws SQLException {
        /*
         * String sql1 = \"update user set user_name=?,password = ? where id=?\";
         * String sql2 = \"update user_actor_droit set actor_id = ?,droit_id =?
         * where user_id=?\"; try { ps = con.prepareStatement(sql1);
         * ps.setString(1, user.getName()); ps.setString(2, user.getPassword());
         * ps.setString(3, user.getId()); ps.executeUpdate();
         * 
         * ps = con.prepareStatement(sql2); Actor actor = user.getActor(); for
         * (Iterator<Droit> it = actor.getDroit().iterator(); it.hasNext();) {
         * Droit droit = it.next(); ps.setString(1, actor.getId());
         * ps.setString(2, droit.getId()); ps.setString(3, user.getId());
         * ps.executeUpdate(); } } catch (SQLException e) { e.printStackTrace(); }
         */
        String sql1 = \"update user set name=?,password=?,actor=? where id=?\";
        String sql2 = \"update u_d set droit_id =? where user_id=?\";
        ps = con.prepareStatement(sql1);
        ps.setString(1, user.getName());
        ps.setString(2, user.getPassword());
        ps.setString(3, user.getActor());
        ps.setInt(4, user.getId());
        ps.executeUpdate();
        ps = con.prepareStatement(sql2);
        for(Iterator it = user.getDroits().iterator();it.hasNext();){
            Droit droit  = (Droit) it.next();
            ps.setInt(1, droit.getId());
            ps.setInt(2, user.getId());
            ps.executeUpdate();
        }        
    }
    private Integer sum(String table) {
        String sql = \"select max(id) from \" + table;
        try {
            ps = con.prepareStatement(sql);
            ResultSet rs = ps.executeQuery();
            while (rs.isLast()){
                System.out.println(rs.getInt(1));
                return rs.getInt(1);}
        } catch (SQLException e) {
            e.printStackTrace();
            return 0;
        }
        return 0;
    }
    public boolean close() {
        try {
            ps.close();
            ConnectionFactory.close();
            return true;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }
    public HashSet findByActor(String actor) throws SQLException {
        HashSet users = new HashSet();
        String sql1 = \"select user.id,user.name,user.password,user.actor from user\";
        String sql2 = \"select droit.id,droit.name from u_d,droit where u_d.droit_id=droit.id and u_d.user_id = ?\";
        ps = con.prepareStatement(sql1);
        ResultSet rs = ps.executeQuery();
        while(rs.next()){
            User user = new User();
            user.setId(rs.getInt(1));
            user.setName(rs.getString(2));
            user.setPassword(rs.getString(3));
            user.setActor(rs.getString(4));
            HashSet<Droit> droits = new HashSet();
            ps = con.prepareStatement(sql2);
            ps.setInt(1, user.getId());
            ResultSet rs2 = ps.executeQuery();
            while(rs2.next()){
                Droit droit = new Droit();
                droit.setId(rs2.getInt(1));
                droit.setName(rs2.getString(2));
                droits.add(droit);
            }
            user.setDroits(droits);
            users.add(user);
        }
        return users;
    }
}

我把问号去掉 就不能运行了

System.out.println(rs.getInt(1));
你指这条吗 它没有报错啊 它能够成功的返回数据库中的记录条数

假如你的表中有如下几列

id,name,sex,password,address;

其中id是自动生成的，那么你插入的时候这样写就以了

insert into xxx ([name],[sex],[password],[address]) values(?,?,?,?)

这样就可以了，这样你就可以指定要插入哪几列

你会用断点吗？？
用断点来确定是哪句出现错误，你才能改啊` 我现在是不知道你的错误是哪个地方``