java.lang.NoClassDefFoundError in Eclipse at runtime

[debu37]

Hi All,
I am relatively new to Java.
I am running this program in Eclipse 3.2.
I am calling a method executeOperation() in ExtractBomOperation class by instantiating its object from ExtractBomDialog class and then calling that method. However at executeOperation() at the line
"wb = new HSSFWorkbook();" I am getting a run time error that in Eclipse console shows as : "java.lang.NoClassDefFoundError: org/apache/poi/hssf/usermodel/HSSFWorkbook" . I have already included poi.jar file in Eclipse.
I am sending the ExtractBomDialog and ExtractBomOperation class codes in this attachment.

Not sure why I am getting the error.Any help would be great.
Thanks in advance.

[ProjectKaiser]

How do you run your app ? As "Java application"or using server ?

[debu37]

As a java application

[Norm]

org/apache/poi/hssf/usermodel/HSSFWorkbook

Do you know which jar file the above class is defined in?
Is that jarfile on the classpath?

[debu37]

The above class is defined in poi.jar.
I added that jar by going to Project(Right CLick)--->Properties--->Java Build Path--->Libraries--->Add External Jars.

Is there anything else I need to do?
How do I check that the jarfile is on classpath in ECLIPSE ?

[Norm]

Ask an eclipse user. There is a separate eclipse Forum here.