I need to load "configuration" type files for my program in Android, they are both .bin files containing dictionary data for the NLP library. I'm a bit new to Android still, and I'm having trouble finding a folder to place the files in so I can access them when the activity starts.
I also need to create/save/load a filetype specific to my program, and I don't know where to put it either. All I've been able to find on here is people using the getAssetManager() function to fetch input streams, but I explicitly need File objects for me to be able to load them into my pre-existing desktop software code I'd like to reuse (plus the libraries require them anyway)
I've also seen people using a "res/raw" folder, however the ADT did not generate this "raw" file when I made the project - so I'm not sure what to do there either.
Here is how I usually start the software in the desktop version, but I need to fetch these files in an Android environment:
brain.start(new File("memboric.core"), new File("en_pos_maxent.bin"), new File("en_sent.bin"));
core = brain.getInterpreter().getCore();
The memboric.core file can be generated, but I need to know WHERE and HOW to do so.
Thank you very much for your time, feel free to direct me to other resources if you feel this question is inadequate.
TLDR; how do I load "static" files for the software to function (needs to be included with software), and how to create/load/save "personal" files into an appropriate area of the device?
Use Context.getFilesDir(). Your application can read and write files in that folder and they'll automatically get deleted if your application gets uninstalled.
From that point forward, you can create, delete and read from files like any other Java application.
the "raw"-folder you can create it on your own. So check this out, which shows how to handle files in Android: http://developer.android.com/training/basics/data-storage/files.html
Related
I've been trying to make jar application that can read a csv file in the same directory as it. This is, however, proving difficult as my means for accessing the file currently is:
InputStream is = getClass().getClassLoader().getResourceAsStream(filename);
Which works for my program running in the IDE and for my tests but doesn't work when I run the program from the compiled jar file. I have no idea how to get it to work for both. I seriously can't understand this path stuff, it seems like there are a million ways to do it and only one of them work for only one specific scenario.
I've been trying to make jar application that can read a csv file in the same directory as it.
Ah, there's your problem. That just isn't a thing.
There are only 2 types of files:
Application Resources
These are read only, and are as much part of your app as your class files are. It is not in any way relevant to think about 'editing' them - that's not the kind of thing they are. It is reasonable to assume that if this resource is somehow missing, the app is as corrupt / misinstalled as it would be if class files are missing.
For this, you use .getResource and .getResourceAsStream. And note that getClass().getClassLoader() is wrong, you want MyClass.class.getResource and then add a slash if you want to go from root (because getClass() potentially breaks when you subclass, and going via classloader is [A] just typing for no reason, and [B] breaks in bootload scenarios. MyOwnClassName.class.getResource never breaks, so, always use that).
This asks java to look in the same place class files are and nowhere else. Your class files are inside the jar files, and not next to them, therefore, it won't find a text file that is sitting next to jar files.
it does not make sense that it does work during development: That means you shoved a file inside the resources folder, which is equivalent to having a CSV file inside the jar file. You must have gone out of your way to tell your build system to do weird things. Don't do that.
If that CSV file is not intended to be user editable it should be inside the jar file and not next to it: That makes it an application resource. Examples of application resources:
You have a GUI, and you need to store the icon files and splash screen art and such someplace.
You ship static data with your app, such as a table of all US states along with the zipcodes they use (could be a text or csv file for example).
Templates of config files. Not config files themselves.
DLLs and the like that you need to unpack (because windows/linux/mac isn't going to look inside jars for them).
You're a webapp and you want to ship the HTML static files along with your webapp.
If this is what your CSV file is, the fix is to put it in the jar, not next to it, then load it with MyClass.class.getResource(name).
Config files and project files
For example:
For a rich text editor (like, say, LibreOffice Writer), the .odt files representing your writings.
Save games for a game.
A config file, which can be edited by the user, or is edited by your own app in a 'preferences' dialog. This stores for example whether to open the app full screen or not, or authentication info for a third party API you're using.
These should not be in the jar, should not be loaded with .getResource at all, and should not be in src/main/resources in the first place.
They also should not be next to your jar! That's an outdated and insecure model (the idea that editable files sit in the same place the app itself sits): A proper OS configuration means that an app cannot write to itself which is most easily accomplished by having it be incapable of writing to its directory. Some OSes (notably, windows) did this wrong for a while.
For example on windows, your app lives in C:\Program Files\MakorisAwesomeApp\makori.jar, and the data files for it live somewhere in C:\Users\UserThatInstalledIt\Documents\MakorisAwesomeApp.
oh linux, your app might be /usr/bin/makori and the data lives somewhere in the home dir. Config data might live in /etc/.
You don't "ship" your config files, you instead make installers that create them. You can do this part in-app by detecting that the relevant config file does not exist, load in a template (that is a resource, shipped inside your jar, loaded with getResource), and write it out, and tell the user to go look at it and edit it.
I really want a CSV file next to my jars!
Well, that's wrong, so, there are no libraries that make this easy. When you want to do silly things its good that APIs don't make that easy, right?
There are really hacky ways to do this. You can use .getResource to get a URL and then 'parse' this. This breaks the classloader abstraction concept (because in java, you can write your own classloaders and they can load from anywhere, not just files or entries in jars), but you can ask for 'yourself' (MyClass.class.getResource("MyClass.class")), pull the URL apart and figure out what's happening - does it start with file://? Then it is a file, so turn it into a j.i.File object, and go from there. Does it start with jar://? find the !, substring out the jar part, and now you know the jar. Make that a java.io.File, ask for the parent dir, and look there for the CSV.
You have to write all this. It's complicated code that is hard to test. You should not do this.
Here the problem: my app will generate some files, and I want to give to the users the opportunity to exchange these files between them.
This requires 3 steps:
Saving the data: easily done in Storage implementing the
functions required by the Externalizable class;
Sharing the data: done (probably, right now it's impossible to check if the
result is correct because the missing step 3) with the sharing
methods offered by the framework, as soon as I understood I needed
to use as mimetype "application/octect-stream";
importing the downloaded data (shared by another user): this one I can't manage to
find a way to make it work. Loading the files from the app's Storage
is easy, but accessing to the folders out of the app's Storage is
something I can't manage to do.
I used FileSystemStorage in the hope of gaining access at least to the Download folder that (mostly) every phone has, but apparently I can't manage to accomplish the task
Using the FileSystemStorage on Android, for example, I have access to
/storage/emulated/0
/storage/emulated/legacy
file:///system
The first two being related to the Storage of the app.
Acceding to file:/// I obtain a long list of folders, a partial list including
media
logs
sdcard
Removable
...
root
...
But when I try to access some of these, they all appear to be empty. Either I make some mistake or the app can't see their content.
So I wonder if there is a way to accomplish the task, namely to have access to the files (probably in the Download folder) the user has downloaded, to import them.
Phone apps live in isolation within the phone. Android literally creates a separate Linux user for every app so they don't step on each other and damage the phone. iOS does similar tricks.
As a result apps can't just write a file to downloads and can't just list all the files there. This would violate the users privacy. So the native API to share a file is usually separate from the files API. We do have a share API in the CN class which lets you share images etc. to an arbitrary OS app. See isNativeShareSupported and share.
Ok, maybe I found a solution for reading the files from the Download folder in an extension of CodenameOne called FileChooser.
According to this blog post it should give access to, between the others, the Download folder (at least in Android).
I'm going to try it and, when everything is ready and tested, edit this reply to say how it worked out for me.
I am trying to create a java standalone program and was wondering if there is a way to have some sort of data storage within my jar?
You see, my initial idea was to use xml files within the jar for reading and writing stuff in. I had no problem reading stuff from the xml files but I was told you cant really edit/create new files within a jar.
I want it so when i send the executable jar to my friend, initial data I have put in will be in it already and then they can just add to or change the data. I find it pretty tricky as it has to be a form of data storage without the internet access or any need for my friend to install anything more.
I decided to go for sqlite in the end. It works exactly how i want it to work. I might look into javaDB in the future as it seems to have better SQL language support sqlite.org/cvstrac/wiki?p=SqliteVersusDerby
As far as I know, JAR files are read-only, which cannot be rewritten to.
My suggestion is to use MS Access database as your JAR's data keeper.
As it is portable, the only weakness is that you have to bring both of your JAR and MDB files together (or put them in 1 folder).
I have a small java utility application which performs tasks on remote computers. This app will provide user with a dropdown/combobox where they can enter ip address or hostnames for the computers they wish to connect to. It would be nice if the users could have a history of items/hosts they had connected in the dropdown.
I thought that I can create a file inside the distributable jar and use it to maintain the history. But writing to a file inside the jar seems to be impossible? The alternate approaches would be to use text files, databases etc located outside the jar. But this is not quite I would like to do as my utility app is only one file and I would like it to be completely independent of any external files. Also its not nice to have a text file stick around your jar file or create a text file each time your app is run.
Considering this case what options can I use? Are there any apis that can help in storing or keeping history?
Why don't you store this info with an hidden file in the user home directory? Many application do the same thing.
You can get the user home directory in this way
String userhome = System.getProperty("user.home");
I'd recommend keeping some .dat file somewhere associated with the JAR. Could be in same directory, or in the user's home (as #dash1e recommends) to avoid any permissions issues. I think you'll find that's the simplest solution.
Another option would be to use a Java-based database solution which could be bundled into your JAR (see Apache Derby, et al). Note that this would create files somewhere, but you wouldn't have to worry about the file-level management, as you'd just be interacting with it as a database.
One final option, if you really insist on avoiding having to maintain your own file, would be to use the Java Preferences API which provides an OS-agnostic way of storing data on the system in some obfuscated location. This is arguably a bit of a misuse of the goal of this API, but would accomplish what you're asking for.
We have to make a Java application demo available on Internet using JWS. It goes pretty well; all that's missing is making working directory files available for the application.
We know about the getResource() way... The problem is that we have different plugins for the same application and each one require different files (and often different versions of the same files) in their working directory to work properly. So we just change the working directory when we want the application to have a different behavior.
Currently, the demo is packaged in a signed jar file and it loads correctly until it requires a file from the working directory. Obviously, the Internet users of this demo don't have the files ready. We need a way to make these files available to the WebStart application (read/write access) in its working directory.
We've thought of some things, like having the application download the files itself when it starts, or package them in the jar and extract them on startup.
Looking for advices and/or new ideas. I'll continue working on this... I'll update if I ever find something reliable.
Thank you very much!
I said I would share what I found in my research for something that would fit my needs. Here's what I have so far.
I have found that the concept of current working directory (CWD) does not really make sense in the context of a Java Web Start (JWS) application. This had for effect that I stopped trying to find the CWD of a JWS and started looking for other options.
I have found that (no, I didn't know that) you can refer (using getResource()) to a file in the root directory of a JAR file by simply adding a '/' in front of its name. ("/log4j.properties", for example.) The impact of this is that I can now take any file which is only referred to in a read-only manner in the root of that JAR file (which is really only a ZIP file). You can refer to any file in the root of the JAR file using AnyClass.class.getResourceAsStream. That rules out the problem with read-only files required to run the application, at the cost of a switch in the code telling whether the application is run from a valid CWD or from a JWS context. (You can very simply set a property in the JNLP file of the JWS application and check if that property is set or not to know where to look for the file.)
For write-only files (log files in my case), I used the property , adding a directory with the name of the application: <user.home>/.appname and added log files to it.
Read/write files (which I don't have in my case) would probably simply go at the same place than write-only files. The software could deal with uploading them somewhere if needed, once modified, I guess.
That's the way I deal with the problem for now.
Note there is a service you can explicitly ask for, to get file access to the computer (unless you go all the way and ask for full access (which requires signed jar files)).
Then you need to determine where these files need to go - basically you have no idea what is where and whether you may actually write anywhere. You can create tmp-files but those go away.
Would a file system abstraction talking to the JNLP-server do so you store the users data on the server?