I have created a GUI project and compile the program using CMD.
For Creating .jar File, I created manifest.txt and made the jar by using following command:
jar cmf manifest.txt Client.jar *.class
this created a .jar file but when I open the Client.jar a Window pops up saying
"A JAVA Exception has Occurred" but when I run the jar from CMD
java -jar Client.jar 
It runs properly from CMD but not by clicking on it directly.
What Could be wrong ....?
This is my manifest.txt
Main-Class: ClientTextEdit
\n
\n
\n----> newline
these are the .class files:
 ClientTextEdit.class
 ClientTextEdit$1.class
 ClientTextEdit$2.class
 ClientTextEdit$3.class
 ClientTextEdit$4.class
 ClientConnection.class