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jar file doesn't execute

I'm trying to execute jar file of netbeans swing small project.
The file isn't executing.
I need to make it work by double clicking on the jar file that is located in:
C:\Users\armyTik\Documents\NetBeansProjects\Notepad\dist\Notepad.jar
extra details:
properties -> Build -> Packaging -> "Build JAR after compiling" and "Copy Dependent Libraries" are checked.
properties -> run -> Main class: "notepad.NotepadComponent"
In the cmd, by manually executing the jar file I get the following error:
cd C:\Users\armyTik\Documents\NetBeansProjects\Notepad\dist
java -jar Notepad.jar
"Error: Could not find or load main class notepad.Notepad"
What should I do, specifically?
EDIT:
I extracted the jar file and got:
META-INF/MANIFEST.MF
notepad/FileManager.class
notepad/icon.gif
notepad/NotepadComponent$1.class
notepad/NotepadComponent$2.class
notepad/NotepadComponent$3.class
notepad/NotepadComponent$4.class
notepad/NotepadComponent$5.class
notepad/NotepadComponent$6.class
notepad/NotepadComponent$7.class
notepad/NotepadComponent.class
notepad/Thumbs.db
META-INF/MANIFEST.MF content:
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.4
Created-By: 1.8.0_102-b14 (Oracle Corporation)
Class-Path:
X-COMMENT: Main-Class will be added automatically by build
Main-Class: notepad.NotepadComponent
Update2:
I got new exception while trying to open the jar from the cmd:
While opening the project from netbeans, the icon is shown with no exception.
*****When I remove the icons , The jar is working! but I need to keep the icons in the application.

This is because your classpath is not correct.
Try it like this:
java -cp "<PATH>/Notepad.jar" notepad.Notepad
If this does not work then unpack the jar file and confirm the package and class name is correct, Print CLASSPATH env variable or check java and javac versions.

executable jar Could not find or load main class

I've been struggling with this common error and just can't resolve it. This application is composed of multiple packages and runs fine within JCreator (at the moment I need to use this IDE rather than Eclipse).
My manifest file is here (there are 2 blank lines at the end):
Manifest-Version: 1.0
Created-By: 1.6.0_45 (Sun Microsystems Inc.)
Main-Class: C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\main\DPMain
I wrote a bat file to create the jar:
jar -cvfm DPlus.jar C:\COMPILE\MyProjects\douwe\classes\MANIFEST.MF
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\main*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\library*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\command*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\file*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\file\display*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\command*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\file*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\file\display*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\gui*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\gui*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\job*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\job*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\types*.class
C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\util*.class
When I try to execute with the command
C:\COMPILE\MyProjects\douwe\classes>java -jar DPlus.jar
I always get the error:
Error: Could not find or load main class C:\COMPILE\MyProjects\douwe\classes\dykstra\dplus\main\DPMain
Can anyone see what I'm doing wrong here?

Usually this error is due to MANIFEST.MF if the'res no application's entry point has been set.
Your manifest file should have this line of code
Main-Class: YourPackage.DPMain
Alternatively, you can do the following.
java -cp .;app.jar YourPackage.DPMain

In my implementation, there are something different from yours, you can refer:
(1) The folder(before compressed) structure
you need to add a META-INF folder and put your MANIFEST.MF in it
(2) The content in your MANIFEST.MF
I think your should use the package format instead of a folder tree format:
Manifest-Version: 1.0
Main-Class: com.loadtest.mgr.LoadTestStarter

Class not found despite of classpath in MANIFEST

I have this jar:
/mybundle.jar/
de/mybundle/myclass.class
lib/mysql.jar
META-INF/MANIFEST.MF
With the following MANIFEST.MF
Manifest-Version: 1.0
Class-Path: lib/mysql.jar
Main-Class: de.mybundle.myclass
It all seems perfectly correct for me, but when I run
java -jar mybundle.jar
I get a NoClassDefFoundException when the class tries to instantiate one of the MySQL-Library classes.
What did I do wrong?

You can't bundle jar files in other jar files. The paths specified in the Manifest are relative to the location of the jar file you're calling, so in your case relative to the location of mybundle.jar.
You have two options:
Either put the MySQL jar in the lib directory outside of your mybundle.jar.
Create a fat jar, which contains all classes from the required jar files in addition to your own classes. This is available from within Eclipse or Maven.

If your mybundle.jar is in c:/foo, then your mysql.jar has be in c:/foo/lib. The Class-Path in the manifest is relative to the executable JAR the way you've written it.

Failed to load Main-class Manifest Attribute

I am getting following error while executing compiled jar file. I have re installed my java but my problem is not solved yet.
Failed to load Main-class Manifest Attribute from
D:\Tools\Lodable_Creation\dist\Lodable_Creation.jar
Currently by MANIFEST.MF file looks like.
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.1
Created-By: 1.6.0-b105 (Sun Microsystems Inc.)
Main-Class: main
X-COMMENT: Main-Class will be added automatically by build
I am using Netbeans 6.9.1 IDE.

Use a package for your class. Make sure your class looks something like this (notice the package and the public class):
package com.foo;
public class Main {
public static void main(String[] args) {
}
}
After which you can specify Main-Class as so:
Main-Class: com.foo.Main

As adarshr suggested, JVM is not able to find the class because it requires the fully-qualified name in the Main-Class attribute of Manifest file.
Actually, it is not really necessary to specify the main file. You can just give your JAR file as your classpath, and give the fully-qualified name of the class to run it using java.
Say your JAR is myJar.jar and the fully-qualified main file is com.user.Main. Then from the command line, go to the directory which has your JAR File and give :-
java -classpath myJar.jar com.user.Main
And this will run the Main class. You would also need to give the classes (or JARs) in the classpath which are used (imported) in your Main class.
See this link for the details.

I have encountered this error when I have developed projects with a JDK(1.7 in my case) and the installed JRE was an older version(1.6). Try to update your JRE or change the JDK used, if possible, to match your JRE version.

Cannot find class even when jar file is in working directory

I am struggling to get my Java program to run on AIX. I used Eclipse on Windows to create a runnable Jar file, jRams.jar below. I kept on getting a class not found error, until finally I put all the external libraries in the same directory.
$ ls
JAXB2_20081030.jar
JAXB2_20110601.jar
activation.jar
asjava.jar
commons-beanutils-1.8.3.jar
commons-beanutils-bean-collections-1.8.3.jar
commons-beanutils-core-1.8.3.jar
commons-codec-1.5.jar
commons-collections-3.2.1.jar
commons-configuration-1.6.jar
commons-digester-2.1.jar
commons-jxpath-1.3.jar
commons-lang-2.6.jar
commons-logging-1.1.1.jar
commons-logging-adapters-1.1.1.jar
commons-logging-api-1.1.1.jar
jRams.jar
jaxb-api.jar
jaxb-impl.jar
jaxb-xjc.jar
jaxb1-impl.jar
jremote.jar
jsr173_1.0_api.jar
log4j-1.2.16.jar
netty-3.2.4.Final.jar
$
Still, I get the class not found error.
$ java -jar jRams.jar
The java class is not found: com.jbase.jremote.JRemoteException
jremote.jar definitely contains JRemoteException. Why isn't this working?
UPDATE
Thank you for your straight-to-the-point answers. I now understand the nature of a java application and a manifest file far better.
Turns out my ftp client was transferring in ASCII mode and not Binary, so the jar files were corrupt. I have learned a great deal, nonetheless.

When using the -jar option, you need to specify which jar-files should be on your class path in the manifest file. Just having the required jar files in the same directory won't do it.
Add a line in your manifest that says:
Class-Path: JAXB2_20081030.jar:JAXB2_20110601.jar:....:netty-3.2.4.Final.jar
or skip the -jar option and launch using
java -cp JAXB2_20081030.jar:....:netty-3.2.4.Final.jar:jRams.jar pkg.JRamsMain
and it should work fine.
(Note that on *nix systems, as opposed to Windows machines, the jar files in the class paths should be separated using : instead of ;.)
Further reading:
The Java Tutorials: Adding Classes to the JAR File's Classpath

You need to add all those JARs to the runtime CLASSPATH by adding the -classpath parameter. AIX requires you to separate the JARs using :

You will have to specify the full path(if libraries not in the same directory as jRams) or just the names of the jar file in a manifest file (If all dependency jars are in the same folder). Alternative specify the path to all the dependent jars using -cp argument.
Example (This assume every dependency is in the same directory you are executing java command from):
java -cp commons-collections-3.2.1.jar; jaxb-impl.jar; etc.. ;jRams.jar package_to_class.MyMainClass.java
Where package_to_class is example: com.myproj.example.
EDITED.

Follow these steps to add "Class-Path" to existing jar file -
Create "newmanifest" file with following entry
Class-Path: additional/jars
Update existing jar file e.g. "classes.jar"
jar --update --manifest=newmanifest --file classes.jar
Inflate jar file
jar -xvf classes.jar
created: META-INF/
inflated: META-INF/MANIFEST.MF
Verify "Class-Path" is added to MANIFEST.MF
cat META-INF/MANIFEST.MF
Manifest-Version: 1.0
main-class: CLASSNAME
Created-By: 15.0.2 (Oracle Corporation)
Class-Path: additional/jars