java,jbdc，连接数据库,查询数据,报错空指针,咋解决

Question

// 根据传递的参数id，查询对应的玩家信息返回
public Player queryplayer(String id){
Player player=null;
Connection con;
PreparedStatement sta=null;
ResultSet rs = null;
con=PlayerDao.getCon();
String sql="SELECT * FROM Player WHERE pid=?";
try {
sta=con.prepareStatement(sql);
sta.setString(1,id);
while (rs.next()) {
String pid=rs.getString(1);
String pname=rs.getString(2);
String address=rs.getString(3);
player=new Player(pid,pname,address);
}
} catch (SQLException e) {
e.printStackTrace();
}finally {
close(rs,sta,con);
}
return player;
}

private static void select() {
System.out.println("请输入玩家编号:");
String pid=sc.next();
Player player=playerDao.queryplayer(pid);
System.out.println(player);
}

Answer 1

String sql="SELECT * FROM Player WHERE pid=?";，你的id也没放到sql语句里啊