Java save method stops working when .jar is moved

Question

I’m coding my first java Desktop application using eclipse and I’m having difficulty deploying it. My project uses JavaFX2 and the e(fx)clipse plugin, the latter is in charge of generating the build.xml file.

ABOUT THE APP

The app, amongst other things, provides an interface where the user can create categories and associate these with labels. All modifications are saved within a single file (the data is stored as a serialized object.) and are supposed to be loaded automatically when the app is reopened.

THE PROBLEM

When build as an executable jar using a .xml file (Ant), the project runs fine within the folder where it gets created. I can run my application, modify data, and save everything once I’m done. When I reopen the app everything gets loaded as it should.

However, if I copy the folder elsewhere, I can no longer save any data. Everything else seems to work; the app will even load the data that was saved when it was in its original directory. I assume that this means that the app can still see the data file, but can no longer write to it.

WHAT IVE TRIED

I’ve read that warping the .jar around an installer may fix the issue; however, one of the goals for the app was to make it as portable as possible. Meaning that it should be possible to move it around from one directory/computer to another, ideally in a manner that is cross-platform friendly, without the need of installing it.

I’ve tried various things to get it to work. I’ve shifted the whole project to Netbeans (to produce a different build), I’ve modified the save/load method file path to make sure the right document is targeted, I’ve tweaked the .xml file the best I could, and I even tried to build the project using the javafxpackager. No matter what I do, when the build works, I get the same results.

Right now, I’m thinking that there may still be something wrong with the .xml file but I’ve got a hard time understanding how to modify it. Perhaps the problem is somehow caused by the way the data gets serialized. I know that at one point when I moved things around within my project, both the save and load methods could no longer interact with the data.

What I find strange is that when the project is moved the load method still works. If the problem is caused by changing the file path, how come only the save method ceases to function?

APP FILES AND STRUCTURE

+src
    -(Main.java)
    +controller 
        -(misc.javas)
    +modelData  
        -(Library.java) -->the object that is serialized
    +modelLogic
        -(misc.javas)
    +view
        -(misc.javas)
+files
    -(library.data) -->the file where the serialized object is saved
+lib
    -(empty.empty)

So, is their anything I can do to solve my problem?

Thanks in advance.

Answer 1

In the end, the problem was rather simple. When I was moving the app, I was always putting it on the desktop, which, in the case of my PC, sets by default all content as read-only (in relation to the app's privileges). Because of this, the app could not modify any files that were within folders on the desktop.

Therefore, all I had to do was to move the app to another directory, such as C:\randomFolder, and the problem was solved.

So, if anyone has a similar problem, moving the app elsewhere may be the solution. Alternatively, taking full ownership of the folder and its content can also work.

When possible, it is usually better to have the app ask its user for a specific location to save its data.