Java.Lang.Classnotfoundexception in Spite of Using Classpath Environment Variable

java.lang.ClassNotFoundException in spite of using CLASSPATH environment variable

The CLASSPATH environment variable is only used by the java.exe command and even then only when used without any of the -cp, -classpath, -jar arguments. It is ignored by IDEs like Eclipse, Netbeans and IDEA.

That environment variable is in real world also considered a poor practice since it breaks portability. I.e. program X will run successfully while program Y won't run without altering the CLASSPATH. It's only "useful" for Sun Oracle to prevent that starters get tired of typing the same classpath again and again in the -cp or -classpath arguments when following Java tutorials. In real world, batch/shell files are preferred where just the entire command with -cp/-classpath argument is specified.

In your case you're using an IDE. The classpath is there called the "Build Path". In plain Java projects, it represents both the compiletime and runtime classpath. You can configure it in the project's properties. You can add a complete folder, you can add individual/external JAR files, you can link projects, etcetera. Make use of it. Forget about using the CLASSPATH environment variable. It was a mistake by Sun Oracle. They thought to convince starters, but it ended up to be only more confusing to starters as they incorrectly interpret that environment variable as the classpath.

See also:

• How to add JAR libraries to WAR project without facing java.lang.ClassNotFoundException? Classpath vs Build Path vs /WEB-INF/lib

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver

You have to put the full path to the jarfile in the classpath (including the filename):

.;C:\j2sdk1.4.2_16\jre\lib;
C:\Program Files\mysql-connector-java-3.1.144\mysql-connector-java-3.1.14-bin.jar

As Hippo said, you have to restart cmd after changing that. If it doesn't work, launch your program like this:

java -cp ".;C:\j2sdk1.4.2_16\jre\lib;
C:\Program Files\mysql-connector-java-3.1.144\mysql-connector-java-3.1.14-bin.jar"
my.class.Name

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver Vertrigo server eclipse

You need to have mysql connector jar in your classpath while running the program. If you are running it through the command line then you can do something like this:

java -cp  <.;path to sql jar> ShippingCompany

Why am I getting a NoClassDefFoundError in Java?

This is caused when there is a class file that your code depends on and it is present at compile time but not found at runtime. Look for differences in your build time and runtime classpaths.

Classpath contains only the running file

Try don't mix -cp and -jar options, this might work:

java -cp "mysql-connector-java-5.1.26-bin.jar:MyJarFile.jar" my.package.Main

for *nix or

java -cp "mysql-connector-java-5.1.26-bin.jar;MyJarFile.jar" my.package.Main

for windows

where my.package.Main is your main class.

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