Problem in accessing database using a java class

Question

Hy Folks,
I have written a class to retrive data from data base and compiled it.when I said java QueryExample, I am getting the following error message.It is as below.
E:\>java QueryExample
Loading JDBC Driver -> oracle.jdbc.driver.OracleDriver
java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:286)
at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:120)
at QueryExample.<init>(QueryExample.java:37)
at QueryExample.main(QueryExample.java:129)
Creating Statement...
Exception in thread "main" java.lang.NullPointerException
at QueryExample.performQuery(QueryExample.java:70)
at QueryExample.main(QueryExample.java:130)
Now my question is can I run a jdbc program with out using any application server or webserver.
If I can , what are all the packeages I have to down load, and how to set their classpath.
Regards,
Olive.

Answer 1

My basic doubght is can we write a class like this.Here I give the sample code that I am using,,,, and using Oracle9i for Windows release 2 (9.2) .
// QueryExample.java
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;
* The following class provides an example of using JDBC to perform a simple
* query from an Oracle database.
public class QueryExample {
final static String driverClass = "oracle.jdbc.driver.OracleDriver";
final static String connectionURL = "jdbc:oracle:thin:@localhost:1521:O920NT";
final static String userID = "scott";
final static String userPassword = "tiger";
Connection con = null;
* Construct a QueryExample object. This constructor will create an Oracle
* database connection.
public QueryExample() {
try {
System.out.print(" Loading JDBC Driver -> " + driverClass + "\n");
Class.forName(driverClass).newInstance();
System.out.print(" Connecting to -> " + connectionURL + "\n");
this.con = DriverManager.getConnection(connectionURL, userID, userPassword);
System.out.print(" Connected as -> " + userID + "\n");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
* Method to perform a simply query from the "emp" table.
public void performQuery() {
Statement stmt = null;
ResultSet rset = null;
String queryString = "SELECT name, date_of_hire, monthly_salary " +
"FROM emp " +
"ORDER BY name";
try {
System.out.print(" Creating Statement...\n");
stmt = con.createStatement ();
System.out.print(" Opening ResultsSet...\n");
rset = stmt.executeQuery(queryString);
int counter = 0;
while (rset.next()) {
System.out.println();
System.out.println(" Row [" + ++counter + "]");
System.out.println(" ---------------------");
System.out.println(" Name -> " + rset.getString(1));
System.out.println(" Date of Hire -> " + rset.getString(2));
System.out.println(" Monthly Salary -> " + rset.getFloat(3));
System.out.println();
System.out.print(" Closing ResultSet...\n");
rset.close();
System.out.print(" Closing Statement...\n");
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
* Close down Oracle connection.
public void closeConnection() {
try {
System.out.print(" Closing Connection...\n");
con.close();
} catch (SQLException e) {
e.printStackTrace();
* Sole entry point to the class and application.
* @param args Array of String arguments.
* @exception java.lang.InterruptedException
* Thrown from the Thread class.
public static void main(String[] args)
throws java.lang.InterruptedException {
QueryExample qe = new QueryExample();
qe.performQuery();
qe.closeConnection();
}