Question about connection to firebird database

Question

Hi I'm a new JDBC programmer. I picked firebird because the application I wanted to make needed a server-less database. The database was easy to set up (I'm using the classic version of firebird) with isql, and I am now trying to access it through the JDBC. Here is my code, I know the code may be crude looking (I am new to it).
        try
            Class.forName("org.firebirdsql.jdbc.FBDriver");
            Connection con = DriverManager.getConnection("jdbc:firebirdsql:localhost/3050:C:/test.gdb", "sysdba", "masterkey");
        catch(ClassNotFoundException e)
            System.out.println(e.getMessage());
        catch(SQLException e)
            System.out.println(e.getMessage());
        }With this code, I recieved the following exception...:
java.lang.UnsupportedClassVersionError: Bad version number in .class file
     at java.lang.ClassLoader.defineClass1(Native Method)
     at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
     at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
     at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
     at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
     at java.security.AccessController.doPrivileged(Native Method)
     at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
     at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
     at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
     at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
     at java.lang.Class.forName0(Native Method)
     at java.lang.Class.forName(Class.java:164)
     at DatabaseBoundary.hire(DatabaseBoundary.java:16)
     at DatabaseBoundary.<init>(DatabaseBoundary.java:9)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:494)
     at bluej.runtime.ExecServer$3.run(ExecServer.java:808)I have the most updated version of the JDK, and I have the most updated version of firebird (as of March 24, 2008 9:48 PM EST). I don't know why I am getting the UnsupportedClassVersionError, all help would be greatly appreciated. :)

Answer 1

well, apparently you do NOT have the correct version of the Java runtime set up as the one you're actually calling, as that's the only thing that can cause this error.
Most likely there's fragments of an older installation left floating around the system in directories that are higher in the path than your JDK.
Check for example your windows/system32 directory for java*.exe and if they're there, remove them.
After that set up your system path correctly to point to your JAVA_HOME/bin (you should also define JAVA_HOME in your environment variables to point to the JDK installation directory).
The Firebird driver I think is compiled against JDK 1.4, maybe 1.3, so the error is almost certainly caused by your own code being compiled against 1.6 and you're attempt to run it (unwittingly) against 1.5.