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Copy files within JAR to disk

Jos Vermeulen

Joined: Aug 31, 2010
Posts: 1
Hi. I'm a novice trying to learn some Java. Currently working on a small application. A feature in my application is that it holds some files (resources) and copies it to the hard disk.

Running it from Eclipse, it works 100% fine (!!). Unfortunately, when I export my app to a JAR and run it, files from within my application that need to be copied to the hard disk, aren't getting copied...

Here's some code that handles the copying from jar to hard disk:

I'm pretty sure the problem lies in the this.getClass().getResource() part. But not sure on what to fix.

There's probably more efficient code for copying files, but I only need a 'quick fix' for now. Can someone please help me?
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 42590
Don't know. Why are you not using simpler classes? For text files you can use Scanner and Formatter.

That looks too difficult for "beginning Java", so I shall move the discussion.

And welcome to JavaRanch
Rob Spoor

Joined: Oct 27, 2005
Posts: 19990

You can't use,,,, and java.nio.channels.FileChannel with files inside JAR files. That's because technically speaking they are no longer files - they are JAR file entries. You should switch to Class.getResourceAsStream() instead, then use old fashioned stream-based copying.

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I agree. Here's the link:
subject: Copy files within JAR to disk