向数据库中存入数组数据，代码出错怎么解决

Question

这个代码的错误怎么解决？

import java.sql.Connection;
import java.sql.DriverManager;
//import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.sql.PreparedStatement;
import java.sql.PseudoColumnUsage;
//import java.sql.SQLException;
class sql1{
    int id;
    String name;
    int age;    
    public sql1(int id, String name, int age) {
        super();
        this.id=id;
        this.name=name;
        this.age=age;        
    }
    @Override
    public String toString() {
        return "id=" + id + ", name=" + name + ", age=" + age ;
    }
}
public class ASDZ {
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        List<sql1> yu=new ArrayList<>();
        yu.add(new sql1(23,"ykg",12));
        yu.add(new sql1(24,"ykg1",14));
        yu.add(new sql1(25,"ykg2",17));
//        for(sql1 i:yu) {
//            System.out.println(i.toString());
//        }
        Class.forName("com.mysql.jdbc.Driver");
        Connection con=null;
        //Statement stmt=null;
        PreparedStatement  ps=null;
         con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/ykg?useSSL=false","root","03579631");
         //stmt= con.createStatement();
         String sql="insert into yu values(?,?,?)";
         ps=con.prepareStatement(sql);
        for(int i=0;i<yu.size();i++) {
            ps.setInt(1, yu.get(i).id);
            ps.setString(2, yu.get(i).name);
            ps.setInt(3, yu.get(i).age);
            ps.executeUpdate(sql);    
            //Update
        }        
            if(ps!=null) 
                ps.close();
            if(con!=null)
                con.close();
    }
}

运行结果及报错内容

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?,?,?)' at line 1
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3978)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3914)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2530)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2491)
at com.mysql.jdbc.StatementImpl.executeUpdateInternal(StatementImpl.java:1552)
at com.mysql.jdbc.StatementImpl.executeLargeUpdate(StatementImpl.java:2607)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1480)
at ASDZ.main(ASDZ.java:46)

Answer 1

额，你现在用的是PreparedStatement对象，执行的时候要使用executeUpdate()，无参的方法。有参的方法是从Statement来的，所以不会填充参数。
有帮助请采纳，还有不懂的可以继续追问~