Java mysql-connector ClassNotFoundException despite filing posts

Question

Still get compile error ClassNotFoundException from com.mysql.cj.jdbc.Driver

from java-8 mysql-connector-java-5.1.147.jar and mysql-connector-java-5.1.47-bin.jar (though most postings say it is the bin.jar that is needed)

I unpacked the tar file and copied the two mysql-connector jar files to /usr/lib/jvm/java-8-oracle/lib and to my execution folder /var/www/html for overkill Also, I put classpath in /etc/environment , and in java file and when compiling (tried each separately first).

then compiled, tried with and without in compile

Get the same error in all these cases (and other permutations):

Exception in thread "main" java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver

... initially called from bbfq.main

Any other ideas of where I'm not coding the classpath correctly? (this posting may not show the spacing and indents of code as I wrote it)

Thanks.

In /etc/environment:  
JAVA_HOME="/usr/lib/jvm/java-8-oracle/bin"  
export JAVA_HOME  
CLASSPATH=".:/usr/lib/jvm/java-8-oracle/lib:/var/www/html"  
export CLASSPATH

in java file:
import java.sql.*;
import java.io.*;
public class bbfq {
....
Connection con=null;
...
try {
   Class.forName("com.mysql.cj.jdbc.Driver");
   con=DriverManager.getConnection("jdbc:mysql//localhost:3306/drupal7" "id" "password");
....

Manifest file bbfq.mf:
Manifest-Version: 1.0
Class-Path: phidget22.jar mysql-connector-java-5.1.47.jar mysql-connector-java-5.1.47-bin.jar

compiled with and without declaring classpath:
sudo javac -classpath bbfq.java    
or    
sudo javac -classpath .:mysql-connector-java-5.1.47.jar:mysql-connector-java-5.1.47-bin.jar bbfq.java

and tried to run with or without classpath:
sudo java -jar bbfq.jar   
or    
sudo java -classpath .:bbfq:mysql-connector-java-5.1.47-bin.jar -jar bbfq.jar

Thanks.

Answer 1

First, remove Class.forName("com.mysql.ch.jdbc.Driver"); . That has not been necessary for many years, because JDBC drivers are located using the service provider process.

Even if it were warranted, your Class.forName call assumes the driver class is com.mysql.ch.jdbc.Driver. That is no longer the case, and in fact there is no such class in the driver .jar file, so the Class.forName call will always fail.

Second, the -classpath option is ignored when using the -jar option. From the documentation :

When you use -jar , the specified JAR file is the source of all user classes, and other class path settings are ignored.

When you use the -jar option, only the manifest's Class-Path attribute is used to add other files to the classpath.

The Class-Path attribute is actually a list of relative URLs , separated by spaces. They are relative to the .jar file containing the manifest.

So, you must place mysql-connector-java-5.1.47-bin.jar in the same directory as the bbfq.jar for it to be picked up by the classloader when it reads the Class-Path manifest attribute.