Making jars double-clickable please help

Question

i'm having trouble making a jar file double-clickable.... and i'm not entirely sure that i'm making the jar file correctly in the first place.
the program is called clock.java, and i can compile and run it from netbeans. the three classes, ClockView, Timestamp, and clock, are in a directory together, and clock has the main.
in order to make it double-clickable, i'm supposed to have a manifest file called Manifest.mf with a line of code:
Main-Class: clock
which i put in a text file in the same directory as clock, ClockView, and Timestamp. i name it "Manifest.mf".
from command prompt, in the same directory, i've tried typing the jar command several different ways.
jar cvf Manifest.mf clock.jar *.class
-this one makes a Manifest.mf file, but no jar. Manifest.mf is full of computer lang stuff.
jar cvf clock.jar *.class
-this makes a clock.jar, but obviously no manifest file.
these are my questions:
do i need to put in the manifest file when i make the jar? was my command line correct for this if so? is my manifest file correct if so?
if i am supposed to add it later, how do i?
is there some reason i wouldn't be able to make jar files from this directory?
when it does make the jar file, if i double-click it, i get:
Failed to load Main-Class manifest attribute from C:\Documents and Settings\paul\Desktop\java\clock\src\clock\clock.jar
i'm kind of new at this, and i've been trying to figure this out for a while. thanks for the help.

Answer 1

The same problem happened to me .. First every time a tried to run the jar file from the command prompt it echoed lots of error. not finding pertaining to manifest file.
Later i fixed it. And I tell you the easy way how to run the jar file from the command prompt.
When you build the ur project in NetBeans IDE. During running it tells how to run the jar file from the command prompt. But before running your project you need to right - click to your project and choose the properties and choose run and define you main class(you also click browse to automatically find the main class ).
And after that u can build. During building your project in the ouput window running you project on the command prompt is told so you can copy it and paste it in a file with .bat extension and double click to run it/