How do make jar runnable file?
It's a simple procedure. First you have to create your class which jas .java extension, then go to cmd and locate your java file, and write: javac -j "name of your file".java then go to the directory where your file was and there is the runnable jar file. Other option is to DEBUG AND COMPILE your file in the compiler you're using if any. When I say debug and compile I mean do not just RUN the file but compile it first, then go to the directory of your project and there you can find your executable .JAR file.
How do make jar runnable file?
It depends on what your try, is it by either by running a .jar file downloaded from the internet or you have created a .jar file suing for example JCreator.
Running Downloaded .Jar:
If the file you downloaded can't be open, then you have to download the latest java update for you by downloading from the java official website. You have two options here. Download the web installer or the installation package. Once you installed it you can now run java files.
Running a Created .Jar:
Check all of your codes and try searching the internet, you might have a coding problem. Use JCreator to easily debug your java program. And don't install it a .Jar already until it is done.