From acces database tu Java db

Question

hi, i have this problem, i have a project that works just fine using an Acces database , i would like to replace this database with a Java DB Derby database, the database i have already did it, but i can't connect to it, i don't know how to change the lines for this new database, here is the present code:
try
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection c=DriverManager.getConnection("jdbc:odbc:dbruota", "", "");
java.sql.Statement st=c.createStatement();
ResultSet rs;
String sql;
sql="select count(*) from ruota";
rs=st.executeQuery(sql);
rs.next();
max=rs.getInt(1);
i have tried :
try
Class.forName("org.apache.derby.jdbc.ClientDriver");
Connection c=DriverManager.getConnection("jdbc:derby//localhost:1527/dbruota","","");
java.sql.Statement st=c.createStatement();
ResultSet rs;
String sql;
sql="select count(*) from ruota";
rs=st.executeQuery(sql);
rs.next();
but it does not works, thank you very much for your time.

Answer 1

yes, of course, as i said , the old code works fine, the new one (in wich i changed only the two lines of the class and connection):
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package javaapplication3;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
* @author Ciprian
public class Interogadb
     private int max;
public Ds[] dom()
          Ds[] p;
          String s1="",s2="";
          int n,nr=0;
          p=new Ds[1];
          try
               Class.forName("org.apache.derby.jdbc.ClientDriver");
               Connection c=DriverManager.getConnection("jdbc:derby://localhost:1527/ruota", "", "");
               java.sql.Statement st=c.createStatement();
               ResultSet rs;
               String sql;
               sql="select count(*) from ruota";
               rs=st.executeQuery(sql);
               rs.next();
               max=rs.getInt(1);
p=new Ds[max];
               rs.close();
               for (int i=0; i<max; i++)
                    try
                         do
                              n=casuale();
                         while(cont(n,p));
                         sql="select coddomanda,domanda,suggerimento from ruota where coddomanda=" + n;
                         rs=st.executeQuery(sql);
                         if (rs.next())
                              nr=rs.getInt(1);
                              s1=rs.getString(2);
                              s2=rs.getString(3);
                         rs.close();
                    catch(SQLException sq)
               p=new Ds(nr,s1,s2);
               st.close();
               c.close();
          catch(SQLException sq)
          {sq.printStackTrace();}
          catch(Exception e)
          {e.printStackTrace();}
          return p;
     private int casuale()
          int i;
          i= (int)(Math.random()*max)+1;
          return i;
     public boolean cont(int n, Ds[] vett)
          for (int i=0;i<vett.length; i++)
               if (vett[i] != null)
                    if (n==vett[i].getcod())
                         return true;
          return false;
gives the next error on the console:
compile:
run:
java.lang.ClassNotFoundException: org.apache.derby.jdbc.ClientDriver
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 javaapplication3.Interogadb.dom(Interogadb.java:30)
...... and so on..
thank you