错误 - 无法找到或加载主类 [英] Error - Could not find or load main class
问题描述
我想连接我的java程序来连接数据库并检索数据。
编译完美但运行时
我得到这个错误:无法找到或加载主类
I want to connect my java program to connect with database and retrieve the data.
its compile perfectly but runtime
im getting this Error : Could not find or load main class
我已经安装了Java SQL驱动程序并将环境变量的jar路径添加为CLASSPATH
i have installed the Java SQL driver and added the jar path to the Environmental variable as CLASSPATH
import java.sql.*;
public class Java2Sql{
public static void main(String args[]){
String url = "jdbc:mysql://localhost:80/";
String dbName = "test";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "root";
try{
Class.forName(driver).newInstance();
Connection conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt = conn.createStatement();
String strsql = "SELECT * FROM student";
ResultSet res = stmt.executeQuery(strsql);
while(res.next()){
System.out.println("ID :"+res.getString(1));
System.out.println("Name :"+res.getString(2));
System.out.println("Tel :"+res.getString(3));
System.out.println("City :"+res.getString(4));
}
res.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
}
推荐答案
您应该从这里下载驱动程序
和JAR文件需要添加到项目类路径。
and JAR file need to add to project class path.
首先右键单击Eclipse项目,项目 - - >构建路径 - >配置构建路径。在Libraries选项卡下,单击Add Jars或Add External JARs并添加下载的jar
First Right click on you Eclipse Project, Project --> Build Path --> Configure Build Path. Under Libraries tab, click Add Jars or "Add External JARs" and add downloaded jar
不是100%肯定,但看起来你使用的是错误的端口号80.确保你的MySQL端口号是当前的以下语句
Not 100% sure but looks like you are using wrong port number 80. Make sure your MySQL port number is current by below statement
SHOW VARIABLES WHERE Variable_name = 'port';
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