java.lang.NoClassDefFoundError catch-22

[James Kalmadge]

I have a test program that compiles but does not run.
Here is the code which I grabbed from from a web site:

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import java.sql.*;
 
public class ColumnName{
  public static void main(String[] args) {
    System.out.println("Getting Column Names Example!");
    Connection con = null;
    String url = "jdbc:mysql://localhost:3306/";
    String db = "jdbctutorial";
    String driver = "com.mysql.jdbc.Driver";
    String user = "root";
    String pass = "root";
    try{
      Class.forName(driver);
      con = DriverManager.getConnection(url+db, user, pass);
      try{
        Statement st = con.createStatement();
        ResultSet rs = st.executeQuery("SELECT * FROM employee6");
        ResultSetMetaData md = rs.getMetaData();
        int col = md.getColumnCount();
        System.out.println("Number of Column : "+ col);
        System.out.println("Columns Name: ");
        for (int i = 1; i <= col; i++){
          String col_name = md.getColumnName(i);
          System.out.println(col_name);
        }
      }
      catch (SQLException s){
        System.out.println("SQL statement is not executed!");
      }
    }
    catch (Exception e){
      e.printStackTrace();
    }
  }
}
 

Here are the runs:

1 WITH classpath NOT set

java ColumnName
Getting Column Names Example! <-output from line 9
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader$1.run(URLClassLoader.java: 217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 21)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 66)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at ColumnName.main(ColumnName.java:17)

RUN 2 with classpath set
java -classpath /opt/Java/mysql-connector-java-5.0.8/mysql-connector-java-5.0.8-bin.jar ColumnName
Exception in thread "main" java.lang.NoClassDefFoundError: ColumnName
Caused by: java.lang.ClassNotFoundException: ColumnName
at java.net.URLClassLoader$1.run(URLClassLoader.java: 217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 21)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 66)
Could not find the main class: ColumnName. Program will exit.

[James Kalmadge]

Hey,

Found the answer at another similar post here.
Or at least a work-around.

javac -classpath /opt/Java/mysql-connector-java-5.0.8/mysql-connector-java-5.0.8-bin.jar ColumnName.java && java -classpath .:/opt/Java/mysql-connector-java-5.0.8/mysql-connector-java-5.0.8-bin.jar ColumnName

Apparently, this is a classpath issue but I am happy with the work-around for now.