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Java does not give Error!

Here is my code - I am just checking the MySQL database connection.
But first I compiled and ran the program successfully. but then I commented out the Class.forName line.
However, when I compile it, it succeeds without any errors. Why?

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


public class FirstJbdc {
    public static void main(String[] args) {
        Connection cn=null;
        try {
            //Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            System.out.println("Driver loaded successfully");
            cn=DriverManager.getConnection("jdbc:odbc:myDSN","root", "java");
            System.out.println("Database connected successfully....");
            System.out.println(cn);
        } catch (Exception e) {
            // TODO: handle exception
                        e.printStackTrace();
        }
    }
}
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5 answers


Java 1.6 can find the JDBC driver even without using Class.forName.

Here's an important piece of documentation :



The methods DriverManager

getConnection

and getDrivers

have been extended to support the Java Standard Edition service provider mechanism. JDBC 4.0 drivers must include a META-INF/services/java.sql.Driver

. This file contains the name of the JDBC driver implementation java.sql.Driver

. For example, to load a class my.sql.Driver

, the file META-INF/services/java.sql.Driver

will contain the entry:

my.sql.Driver

Applications no longer need to explicitly load JDBC drivers using Class.forName (). Existing programs that currently load JDBC drivers using Class.forName () will continue to work unchanged.

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I'm throwing an error, okay. It's just that

catch (Exception e){
     // here the exception is instantiated, but nothing is done about it
}
Sentence

quietly swallows your exception.



Try

System.out.println( e.getMessage() );

in the catch clause

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NOTE. This only applies to the pre-JDBC 4.0 drivers.

JDBC drivers must have a section static

that registers them with java.sql.DriverManager

when the class is loaded, so it is required Class.forName(String)

.

Details here: http://java.sun.com/j2se/1.3/docs/guide/jdbc/getstart/drivermanager.html

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try {

     //Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
      System.out.println("Driver loaded successfully");
      cn=DriverManager.getConnection("jdbc:odbc:myDSN","root", "java");
      System.out.println("Database connected successfully....");
      System.out.println(cn);
} catch (Exception e) {
    // add the following statement
    System.out.println(e.getMessage());
}

If you add a statement inside the catch block, then compile and run, you will see an error message like -

[Some Com] [Some Driver Manager] Data source name not found and specified default driver not specified

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Without Class.forName()

, the JDBC-ODBC bridge driver is not loaded. JDBC Specification getConnection()

returns null if no driver is found for the URL, no exception is thrown. So this is the expected behavior.

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