Java mysql connectivity

Question

hi
i m trying to connect to mysql database through java. i have mysql-java-connector jars file placed in the JAVA_HOME\jre\lib\ext directory.
now when i try to run this file its starts givin me this error...............
Exception in thread "main" java.lang.NoClassDefFoundError: Test
the java file that im running is this............(Test.java)
import java.sql.*;
import java.util.*;
import java.net.*;
import java.io.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.*;
class Test
     public static void main(String args[])
          System.out.println("Hello");
          System.out.println("Welcome to the world of java");
          System.out.println("Lets learn java.");
          String url="jdbc:mysql://localhost:3306/database";
          Connection con = null;
          Statement stmt = null;
          ResultSet rs = null;
          String query;
          try {
          try{
               Class.forName("com.mysql.jdbc.Driver").newInstance();
          catch(Exception e)
               System.out.println("driver not found"+e.getMessage());
               con = DriverManager.getConnection (url, "", "");
               stmt = con.createStatement();
               query = "select * from test;";
               ResultSet result = stmt.executeQuery(query);
               while(result.next())
               String callNumResult = result.getString("name");
               System.out.println(callNumResult);
          catch(Exception e)
               System.out.println("SQLException caught: " + e.getMessage());
          finally {
               try {
                    if (con != null) con.close();
               catch (SQLException e) {}
i have also tried adding that mysql-java connector jar file to the classpath........
but all in vain.....the error persists.
plz help me with it.........
ankur

Answer 1

hi
i m trying to connect to mysql database through java.
i have mysql-java-connector jars file placed in the
JAVA_HOME\jre\lib\ext directory.That's a terrible place to put them. Only language extensions (e.g., packages that start with javax) belong in there. Put that JAR closer to your application.
>
now when i try to run this file its starts givin me
this error...............
Exception in thread "main"
java.lang.NoClassDefFoundError: TestLook at the exception: it's complaining about Test, NOT the MySQL JDBC driver class.
You obviously don't understand how CLASSPATH works:
http://java.sun.com/j2se/1.4.2/docs/tooldocs/windows/classpath.html
I think you have to add the current directory to the CLASSPATH in order to run your Test:
java -classpath . TestNote the "dot" after -classpath. That tells the class loader to start looking in the current directory. since your Test.java doesn't have a package statement, I'm assuming that Test.class is in the same directory as Test.java.
>
>
>
the java file that im running is
this............(Test.java)
import java.sql.*;
import java.util.*;
import java.net.*;
import java.io.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.*;
class Test
public static void main(String args[])
System.out.println("Hello");
System.out.println("Welcome to the world of java");
System.out.println("Lets learn java.");
String url="jdbc:mysql://localhost:3306/database";
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
String query;
try {
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
catch(Exception e)
System.out.println("driver not found"+e.getMessage());
con = DriverManager.getConnection (url, "", "");
stmt = con.createStatement();
query = "select * from test;";
ResultSet result = stmt.executeQuery(query);
while(result.next())
String callNumResult = result.getString("name");
System.out.println(callNumResult);
catch(Exception e)
System.out.println("SQLException caught: " +
e.getMessage());
finally {
try {
if (con != null) con.close();
catch (SQLException e) {}
i have also tried adding that mysql-java connector jar
file to the classpath........
but all in vain.....the error persists.
plz help me with it.........
ankur