Java Servlet-在同一文件夹中找不到符号-对象

我写了以下两节课：

Equipment.java

class Equipment{

  private int id;
    private String name;
    private String local;

  public void setId(int id){
    this.id = id;
  }

  public void setName(String n){
    this.name = n;
  }
  public void setLocal(String l){
    this.local = l;
  }

  public int getId(){
    return this.id;
  }

  public String getName(){
    return this.name;
  }
  public String getLocal(){
    return this.local;
  }

}

JDBCCommands.java

import java.util.*;
import java.sql.*;

class JDBCCommands{
  private static Connection con = new ConnectionFactory().getConnection();

  public static void Create(String name, String local){
    String sql = "insert into equipment (name,local) values (?,?)";
    try{
      PreparedStatement ps = con.prepareStatement(sql);
      ps.setString(1, name);
      ps.setString(2, local);
      ps.execute();
      ps.close();
    }catch(SQLException erro_sql){
      throw new RuntimeException(erro_sql);
    }
  }

  public static List<Equipment> Show(){
    List <Equipment> Components = new ArrayList <Equipment> ();
    String sql = "select * from equipment";
    try{
      PreparedStatement ps = con.prepareStatement(sql);
      ResultSet rs = ps.executeQuery();
      while(rs.next()) {
        Equipment e = new Equipment();
        e.setId(Integer.parseInt(rs.getString("equip_id"))  );
        e.setName(rs.getString("nome"));
        e.setLocal(rs.getString("local"));
        Components.add(e);
      }
      rs.close();
      ps.close();
      return Components;
    }catch(SQLException erro_sql){
      throw new RuntimeException(erro_sql);
    }
  }

  public static void Update(int id, String name, String local){
    String sql = "update equipment set name = ?, local = ? where equip_id = ?";
    try{
      PreparedStatement ps = con.prepareStatement(sql);
      ps.setString(1, name);
      ps.setString(2, local);
      ps.setInt(3, id);
      ps.execute();
      ps.close();
    }catch(SQLException erro_sql){
      throw new RuntimeException(erro_sql);
    }
  }

  public static void Delete(int id){
    String sql = "delete from equipment where equip_id = ?";
    try{
      PreparedStatement ps = con.prepareStatement(sql);
      ps.setInt(1, id);
      ps.execute();
      ps.close();
    }catch(SQLException erro_sql){
      throw new RuntimeException(erro_sql);
    }
  }

  public static List<Equipment> Search(String name, String local){
    List <Equipment> Components = new ArrayList <Equipment> ();
    String sql = "select * from equipment where name like ? and local like ?";
    try{
      PreparedStatement ps = con.prepareStatement(sql);
      ps.setString(1, "%" + name + "%");
      ps.setString(2, "%" + local + "%");
      ResultSet rs = ps.executeQuery();
      while(rs.next()) {
        Equipment e = new Equipment();
        e.setId(Integer.parseInt(rs.getString("equip_id"))  );
        e.setName(rs.getString("nome"));
        e.setLocal(rs.getString("local"));
        Components.add(e);
      }
      rs.close();
      ps.close();
      return Components;
    }catch(SQLException erro_sql){
      throw new RuntimeException(erro_sql);
    }
  }
}

问题是当我尝试这个课程时：

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

import java.sql.*;

class ListEquipment extends HttpServlet {
  protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

        PrintWriter out = response.getWriter();
        JDBCCommands jdbc = new JDBCCommands();

        System.out.println("<table style=\"width:100%\">");
        for(Equipamento c : jdbc.Show()){
          System.out.println("<tr>");
          System.out.print("<th>" + c.getId() + "</th>");
          System.out.print("<th>" + c.getName() + "</th>");
          System.out.print("<th>" + c.getLocal() + "</th>");
          System.out.println("</tr>");
        }
        System.out.println("</table>");
    }
}

符号：类jdbc命令

位置：class ListEquipment

java:13:错误：找不到符号

    JDBCCommands jdbc = new JDBCCommands();
    ^

    JDBCCommands jdbc = new JDBCCommands();
                            ^

    for(Equipment c : jdbc.Show()){
        ^

符号：类jdbc命令

位置：class ListEquipment

java:16:错误：找不到符号

    JDBCCommands jdbc = new JDBCCommands();
    ^

    JDBCCommands jdbc = new JDBCCommands();
                            ^

    for(Equipment c : jdbc.Show()){
        ^

符号：等级设备

位置：class ListEquipment

3个错误

---

所有文件都在同一文件夹中，且名称正确。如何修复此问题？

我只需要将与MariaDB连接的.jar文件放在lib文件夹中，现在一切正常。

也许可以公开您的类。检查servlet和JDBCCommand类是否在同一个包中，或者是否清理您的项目。在eclipse中，转到Project->clean。在intelij中，转到文件->使缓存无效。然后编译你的项目。我希望这有帮助you@DevilsHnd我公开了这些类，但它不起作用。@Prabath jdbc命令与servlet位于完全相同的文件夹中。