Question

我正在实施一个简单的教程

将java程序连接到java DB 使用NetBeans 7 IDE 。这是教程的链接。

http://www.homeandlearn.co.uk/java/connect_to_a_database_using_java_code.html

但是当我运行该项目时，NetBeans给了我以下错误：

run:
java.lang.VerifyError: Constructor must call super() or this() before return in method   database_console.DBConnect.<init>()V at offset 0
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2442)
    at java.lang.Class.getMethod0(Class.java:2685)
    at java.lang.Class.getMethod(Class.java:1620)
    at sun.launcher.LauncherHelper.getMainMethod(LauncherHelper.java:492)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:484)
Exception in thread "main" Java Result: 1
BUILD SUCCESSFUL (total time: 12 seconds)

以下是项目的代码

    package database_console;

    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;

  public static void main(String[] args) {           
            try {
          String host = "jdbc:derby://localhost:1527/Employees";
          String uName="faisal";
          String uPass="password";
          Connection con=DriverManager.getConnection(host, uName, uPass);        
            }
           catch ( SQLException err ) {
    System.out.println( err.getMessage( ) );
    }
        }
    }

解决此问题的任何可用建议

Answer 1

如果上面的代码是您正在使用的代码，那么您需要将整个代码放在课堂上。

//Package declarations (if any)
//Import packages
public class className {

    public static void main(String[] args) {
        //Other code
    }
}

Answer 2

请将课程添加到您的主要（）。喜欢以下

package database_console;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBConnect 
{

    public static void main(String[] args) 
    {
        try 
        {
            String host = "jdbc:derby://localhost:1527/Employees";
            String uName = "faisal";
            String uPass = "password";
            Connection con = DriverManager.getConnection(host, uName, uPass);
        } 
        catch (SQLException err) 
        {
            System.out.println(err.getMessage());
        }
    }
}

Answer 3

您没有关注正确链接的tutorial。

您的代码应如下所示：

package database_console;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBConnect {  // <--- This is missing from your code

    public static void main(String[] args) {
        try {
            String host = "jdbc:derby://localhost:1527/Employees";
            String uName = "faisal";
            String uPass = "password";
            Connection con = DriverManager.getConnection(host, uName, uPass);
        } catch (SQLException err) {
            System.out.println(err.getMessage());
        }
    }  // <--- This is also missing from your code
}

它应该位于名为DBConnect.java

的包中名为database_console的文件中

Answer 4

此类用于创建数据库连接

import java.sql.Connection;
import java.sql.*;

public class GetDBConnection 
{
    public static Connection getConnection(String[] args) 
    {
        String host = "jdbc:derby://localhost:1527/Employees";
        String uName="faisal";
        String uPass="password";
        Connection con=null;
        try 
        {
              con=DriverManager.getConnection(host, uName, uPass);        
        }
        catch ( SQLException err ) 
        {
        System.out.println( err.getMessage( ) );
        }
        return con;
    }

}

这个类用于获取连接并使用它

public class UseDBConnection 
{
    public static void main(String[] args) 
    {
        GetDBConnection object = new GetDBConnection();
        System.out.println("now you can use this DB like you want it and can create as many connection as you want");
    }
}

使用java程序连接到java DB

4 个答案: