Laurent Hinoul

“Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.” - John F. Woods

How to use a JNLP file

This weekend, someone asked me for help with a specific file. He has an Audi and wanted to upgrade his GPS maps. But all he has was an 8 KB downloader file with a JNLP extension. When opening the file, he gets an error that says that the extension is not recognized.

First, I’ll give you Oracles explanation of JNLP:

Java Network Launch Protocol (JNLP) enables an application to be launched on a client desktop by using resources that are hosted on a remote web server.

Ok, we know 2 things:

  • Java is needed, that explains the unrecognized problem
  • It will download hosted files, that’s why the JNLP is only 8 KB

If you don’t have java, install it by downloading it here: https://www.java.com/nl/download/

When installed, look if the icon of the JNLP file changes to a java icon. If so, double press the icon and it should start a program.

If you still get the unrecoginzed extension error you need an extra thing to do. To open a JNLP, javaws.exe is used. This can be found in the bin folder where you installed java. An example location is: C:\Program Files\Java\jre7\bin\javaws.exe

So you can do 2 things here:

  1. Open it through your terminal
  2. Choose a default application to open a JNLP file

1. Run your JNLP file through the terminal

Execute the following command in your terminal:

Note that your javaws.exe installation directory can be different!

2. Select javaws as default application for JNLP files

  • Right click on your JNLP file
  • Select “open with”
  • Select “choose another app”
  • Go to your javaws.exe directory and select javaws.exe
  • Make sure you enable “Always use this app to open .jnlp files”

Now the JNLP file’s icon should change to a java icon. Now double click the JNLP file and it should run.

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