Java 编译错误找不到符号方法 next()答案

【问题标题】：Java compile error cannot find symbol method next()Java 编译错误找不到符号方法 next()
【发布时间】：2021-02-28 16:15:12
【问题描述】：

当我运行我的程序时，出现如下编译错误：

com/mycompany/sistemcatatpoinkeaktifan/KemahasiswaanController.java:[65,20] cannot find symbol
  symbol:   method next()
  location: variable rs of type javax.xml.transform.Result
com/mycompany/sistemcatatpoinkeaktifan/KemahasiswaanController.java:[66,51] cannot find symbol
  symbol:   method getInt(java.lang.String)
  location: variable rs of type javax.xml.transform.Result
com/mycompany/sistemcatatpoinkeaktifan/KemahasiswaanController.java:[66,71] cannot find symbol
  symbol:   method getString(java.lang.String)
  location: variable rs of type javax.xml.transform.Result
com/mycompany/sistemcatatpoinkeaktifan/KemahasiswaanController.java:[66,102] cannot find symbol
  symbol:   method getInt(java.lang.String)
  location: variable rs of type javax.xml.transform.Result
4 errors

 /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.mycompany.sistemcatatpoinkeaktifan;

import java.net.URL;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ResourceBundle;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Menu;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javax.xml.transform.Result;


public class KemahasiswaanController implements Initializable {
    @FXML
    private TextField inputKegiatan;
    @FXML 
    private Button buttonCreate;
    @FXML
    private Button buttonUpdate;
    @FXML
    private Button buttonDelete;
    @FXML
    private TableView<Menu> tvMenu;
    @FXML
    private TableColumn<Menu, Integer> colnomor;
    @FXML
    private TableColumn<Menu, String> coljenisKegiatan;
    @FXML
    private TableColumn<Menu, Integer> colpoin;
    
    public Connection getConnection(){
        try{
            Class.forName("org.sqlite.JDBC");
            Connection conn = DriverManager.getConnection("jdbc:sqlite:E:\\Documents\\Sem 5\\RPL\\punya maria\\SistemCatatPoinKeaktifanMaria\\db\\database.db");
            return conn;
        } catch (Exception e){
            System.out.println(e.getMessage());
            return null;
        }
    }
    public ObservableList<Menu> getMenuList(){
        ObservableList<Menu> menuList = FXCollection.observableArrayList();
        Connection conn = getConnection();
        String query = "SELECT JenisKegiatan, Poin FROM KemahasiswaanNatasha";
        Statement st;
        Result rs;
        ObservableList<Menu> MenuList = null;
        try{
           st = conn.createStatement();
           rs = (Result) st.executeQuery(query);
           Menu KegiatanKemahasiswaan;
           while(rs.next()){
               KegiatanKemahasiswaan = new Menu(rs.getInt("nomor"), rs.getString("jenisKegiatan"), rs.getInt("poin"));
               MenuList.add(KegiatanKemahasiswaan);
           }
        }catch(SQLException ex){
            ex.printStackTrace();
            
        }
        return MenuList;
    }
    public void ShowMenu(){
        ObservableList<Menu> list = getMenuList();
        colnomor.setCellValueFactory(new PropertyValueFactory<Menu, Integer>("nomor"));
        coljenisKegiatan.setCellValueFactory(new PropertyValueFactory<Menu, String>("Kegiatan"));
        colpoin.setCellValueFactory(new PropertyValueFactory<Menu, Integer>("Poin"));
        tvMenu.setItems(list);
    }
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        ShowMenu();
    }    

    private static class FXCollection {

        private static ObservableList<Menu> observableArrayList() {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }

        public FXCollection() {
        }
    }
    
}

【问题讨论】：

找不到符号 symbol: method next() location: variable rs of type javax.xml.transform.Result => 这意味着 Result 类没有 next() 方法，但你尝试在某个地方调用它。很可能，您的意思是 ResultSet 或类似的东西
确实，您错误地将 executeQuery 的结果转换为 Result，这应该是 java.sql.ResultSet
a) 基本上与 javafx 无关 - 调试涉及尽可能多地隔离问题 b) java 命名约定 c) 请将堆栈跟踪格式化为代码 - 按原样不可读:)
嘿..你为什么要恢复格式？有人为你做了你的工作，你又把它毁了？ *难以置信

标签： java sqlite jdbc

【解决方案1】：

问题是您已将rs 声明为javax.xml.transform.Result 类型而不是java.sql.ResultSet，并且您尝试调用的方法（如next()、getInt(String) 和getString(String)在javax.xml.transform.Result 中不存在。

线

Result rs;

应该是

ResultSet rs;

和

rs = (Result) st.executeQuery(query);

应该是

rs = st.executeQuery(query);

此外，您可以通过了解try-with-resources 进一步改进您的代码，因为您目前正在泄漏连接、语句和结果集。

【讨论】：