Question

有人可以看看这个并告诉我为什么我会收到此错误。我试图从Mysql数据库中拉出一个表并将其打印到文本文件中。我给出了上面列出的错误。

package db;

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

public class TableToTextFile {
    public static void main(String[] args) {
        List<int[]> data = new ArrayList();

        try {
            Connection con = null;
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/test", "root", "root");
            Statement st = con.createStatement();
            ResultSet rs = st.executeQuery("Select * from employee");

            while (rs.next()) {
                String id = rs.getString("emp_id");
                String name = rs.getString("emp_name");
                String address = rs.getString("emp_address");
                String contactNo = rs.getString("contactNo");
                data.add(id + " " + name + " " + address + " " + contactNo);

            }
            writeToFile(data, "Employee.txt");
            rs.close();
            st.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }

    private static void writeToFile(java.util.List list, String path) {
        BufferedWriter out = null;
        try {
            File file = new File(path);
            out = new BufferedWriter(new FileWriter(file, true));
            for (String s : list) {
                out.write(s);
                out.newLine();

            }
            out.close();
        } catch (IOException e) {
        }
    }
}

Answer 1

可能是因为您的列表已被声明为接受整数数组并且您传入了一个字符串。

List<int[]> data = new ArrayList();

将其更改为接受字符串。

List<String> data = new ArrayList<>();

更好，更面向对象的设计是创建一个名为Employee的类并使用它。

public class Employee {
    private String id;
    private String name;
    ...
}

List<Employee> data = new ArrayList<>();

类型不匹配：无法从元素类型Object转换为String

1 个答案: