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Thread: jdbc connection problem

  1. #1
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    Default jdbc connection problem

    i don't know what is the problem with my code,
    can pls someone help me on this one, pls.

    hire's my code:
    import java.sql.*;
     
    public class Connect {
    	public static void main(String[] args) {
    		Connection conn = null;
     
    		try {
    			String userName = "root";
    			String password = "kickass";
    			String url = "jdbc:mysql://localhost:3306/student";
    			Class.forName("com.mysql.jdbc.Driver").newInstance();
    			conn = DriverManager.getConnection(url, userName, password);
    			System.out.println("Database connection established");
    		} catch (Exception e) {
    			System.err.println("Cannot connect to database server: " + e.getMessage());
    		} finally {
    			if (conn != null) {
    				try {
    					conn.close();
    					System.out.println("Database connection terminated");
    				} catch (Exception e) { /* ignore close errors */
    				}
    			}
    		}
    	}
    }

    and hire's the error:
    Cannot connect to database server: com.mysql.jdbc.Driver


  2. #2
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  3. #3
    Super Moderator Json's Avatar
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    Default Re: jdbc connection problem

    A simple guess is that the database is not running or there is a firewall blocking the connection.

    But just to rule out other issues, change your code to this, run it and paste the output in this thread again.

    import java.sql.*;
     
    public class Connect {
    	public static void main(String[] args) {
    		Connection conn = null;
     
    		try {
    			String userName = "root";
    			String password = "kickass";
    			String url = "jdbc:mysql://localhost:3306/student";
    			Class.forName("com.mysql.jdbc.Driver").newInstance();
    			conn = DriverManager.getConnection(url, userName, password);
    			System.out.println("Database connection established");
    		} catch (Exception e) {
    			System.err.println("Cannot connect to database server: " + e.getMessage());
                            [b]e.printStackTrace();[/b]
    		} finally {
    			if (conn != null) {
    				try {
    					conn.close();
    					System.out.println("Database connection terminated");
    				} catch (Exception e) { /* ignore close errors */
    				}
    			}
    		}
    	}
    }

    // Json
    Last edited by Json; June 11th, 2010 at 07:36 AM.

  4. #4
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    Default Re: jdbc connection problem

    Another quess is that the Class.forName() is not finding the class.

  5. The Following User Says Thank You to Norm For This Useful Post:

    Json (June 14th, 2010)

  6. #5
    Super Moderator Json's Avatar
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    Default Re: jdbc connection problem

    Thats a more likely one indeed.

    // Json

  7. #6
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    Default Re: jdbc connection problem

    sorry for late reply, hire is the error.
    i don't get this, please help me on this one. tnx
    Cannot connect to database server: com.mysql.jdbc.Driver
    java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    	at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    	at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
    	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
    	at java.lang.Class.forName0(Native Method)
    	at java.lang.Class.forName(Class.java:169)
    	at test.Connect.main(Connect.java:13)

  8. #7
    Super Moderator Norm's Avatar
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    Default Re: jdbc connection problem

    ClassNotFoundException: com.mysql.jdbc.Driver
    The JVM is not finding the class named in the error message. You need to find the jar file containing that class and add it to the classpath for the JVM, so it can find it.

  9. #8
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    Default Re: jdbc connection problem

    can you give a step by step procedure, if its ok, im using eclipse IDE, tnx.

  10. #9
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    Default Re: jdbc connection problem

    Sorry I don't use an IDE.

  11. #10
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    Default Re: jdbc connection problem

    I had the same problem.
    You need to download Connector/J ( MySQL :: Download Connector/J ).
    Now add the path of the mysql-connector-java-3.1.14-bin.jar(I downloaded this one) file to CLASSPATH.
    set CLASSPATH=%CLASSPATH%;c:\<file location in >\mysql-connector-java-3.1.14-bin.jar;

  12. #11
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    Default Re: jdbc connection problem

    Just download the connector like described above, put the connector jar file in your applications lib folder, in eclipse right click your project, click properties.

    Click "Java Build Path" on the left.
    Go to the "Libraries" tab.
    Click "Add Jars"
    Browse to the projects lib folder and add the connector jar file
    Close all dialogs and try running the program in Eclipse like normal.

    // Json

  13. #12
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    Default Re: jdbc connection problem

    use this
    driver to connect and use connectorJ Driver and keep the jar file in the class path
    this solves ur problem
    org.git.mm.mysql.driver

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