Newby Needs Help Connecting to Oracle Database

Question

I'm very very new to java. I'm trying to write a program to connect to and read some fields in an oracle table. I'm having problems and am not sure how to correct it. I downloaded and installed the oracle thin driver. I'm using Eclipse 3.3 and JRE 1.6. This is my code:
import java.sql.*;
public class One {
     public static void main(String[] args) {
          try {
               DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
               System.out.println("let's connect");
               Connection conn=DriverManager.getConnection(
          "jdbc:oracle:thin:@a571p05.pt.com:1521:orap1","username","password");
                    System.out.println("I'm connected");
                    Statement stmt=conn.createStatement();
                    ResultSet rset=stmt.executeQuery(
                         "select CUSTNUM,CUST_LNAME from TBL.CUSTOMER where " + "CUSTNUM=\"12345678900\"");
               System.out.println("Result set?");
               while (rset.next())
                    System.out.println(rset.getString(1)); //Print col 1
               stmt.close();
          catch(Exception x) {
               System.out.println("Unable to connect!");
          System.exit(0);
If I just run it, this is the output:
let's connect
I'm connected
Unable to connect!
So, it looks like it may be connecting, at least it runs the line that establishes the connection then the next line which prints a comment. However, it seems to fail at some point thereafter. I've tried debugging it and as far as I can tell, it's erroring out on thie line:
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
with this stack trace:
Thread [main] (Suspended)     
     ClassNotFoundException(Throwable).<init>(String, Throwable) line: 217     
     ClassNotFoundException(Exception).<init>(String, Throwable) line: not available     
     ClassNotFoundException.<init>(String) line: not available     
     ClassLoader.findBootstrapClass(String) line: not available [native method]     
     Launcher$ExtClassLoader(ClassLoader).findBootstrapClass0(String) line: not available     
     Launcher$ExtClassLoader(ClassLoader).loadClass(String, boolean) line: not available     
     Launcher$AppClassLoader(ClassLoader).loadClass(String, boolean) line: not available     
     Launcher$AppClassLoader.loadClass(String, boolean) line: not available     
     Launcher$AppClassLoader(ClassLoader).loadClass(String) line: not available     
     Launcher$AppClassLoader(ClassLoader).loadClassInternal(String) line: not available     
     One.main(String[]) line: 8     
I checked the project properties\java build path and I have JDBC_THIN_DRIVER and JRE_SYSTEM_LIBRARY listed there. Do I need something else? I'm not quite sure what I'm missing or what the errors are telling me. Any help, or pointers are appreciated. Thanks much!

Answer 1

I would write that class more like this, assuming that customer ID is a String:
import java.sql.*;
public class One
   private static final String DEFAULT_DRIVER = "com.oracle.jdbc.Driver";
   private static final String DEFAULT_URL = "jdbc:oracle:thin:@a571p05.pt.com:1521:orap1";
   private static final String DEFAULT_USERNAME = "username";
   private static final String DEFAULT_PASSWORD = "password";
   private static final String SQL = "select CUSTNUM,CUST_LNAME from TBL.CUSTOMER where CUSTNUM=?";
   private static final String DEFAULT_CUSTOMER_ID = "12345678900";
   public static void main(String[] args)
      Connection conn = null;
      PreparedStatement stmt = null;
      ResultSet rset = null;
      try
         Class.forName(DEFAULT_DRIVER);
         conn = DriverManager.getConnection(DEFAULT_URL, DEFAULT_USERNAME, DEFAULT_PASSWORD);
         stmt = conn.prepareStatement(SQL);
         String customerId = ((args.length > 0) ? args[0] : DEFAULT_CUSTOMER_ID);
         stmt.setString(1, customerId);
         rset = stmt.executeQuery();
         while (rset.next())
            System.out.println(rset.getString(1));
      catch (Exception x)
         x.printStackTrace();
      finally
         close(rset);
         close(stmt);
         close(conn);
   private static void close(Connection conn)
      try
         if (conn != null)
            conn.close();
      catch (SQLException e)
         e.printStackTrace();
   private static void close(Statement stmt)
      try
         if (stmt != null)
            stmt.close();
      catch (SQLException e)
         e.printStackTrace();
   private static void close(ResultSet rset)
      try
         if (rset != null)
            rset.close();
      catch (SQLException e)
         e.printStackTrace();
}%