Save information from Java application

Question

I'm making an application using databases in Java (compiled as JAR). In order to connect to the database, the user must enter the database's address. It would be a pain to remember/type the address every time you want to use the program.

Thus, I want to save the address to a text file somewhere...but where? I want this application to be accessible to anyone on any operating system, and I'd prefer not to have my JAR in a folder.

Is it possible, maybe, to write/read from a text file located within the JAR itself?

If you add something like a `.properties` file in whichever package you want within your jar, it is accessible from the classloader. — Sotirios Delimanolis, Mar 04 '13 at 20:51
See http://stackoverflow.com/questions/194349/what-is-the-proper-way-to-store-apps-conf-data-in-java — vanje, Mar 04 '13 at 20:59

score 1 · Accepted Answer · edited May 23 '17 at 12:27

Like Sotirios Delimanolis said you can create and save a properties file.

It is very simple to do it please have a look at the example below (see the original the post)

package test;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

public class WritePropertiesFile {
 public static void main(String[] args) {
  try {
   Properties properties = new Properties();
   properties.setProperty("favoriteAnimal", "marmot");
   properties.setProperty("favoriteContinent", "Antarctica");
   properties.setProperty("favoritePerson", "Nicole");

   File file = new File("test2.properties");
   FileOutputStream fileOut = new FileOutputStream(file);
   properties.store(fileOut, "Favorite Things");
   fileOut.close();
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }

 }
}

I would not suggest you save the properties file into the jar file however it is possible to do so.

Please follow the stackoverflow answer at: how to write into a text file in Java

If you just save the file like the example, without a path, it'll be saved in the root directory of .jar/.class file. You can also save it in the user directory by getting the system user path, making it user specific. In this case is usual to save in a "\.nameOfYourApplication\" folder. — emportella, Mar 05 '13 at 01:58

score 0 · Answer 2 · answered Mar 04 '13 at 20:56

0

You can open a file anywhere in your jar using e.g. ClassLoader.getResourceAsStream()

answered Mar 04 '13 at 20:56

Tom

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But can I write to the file? – Joel Christophel Mar 04 '13 at 21:04

martinez314 · Answer 3 · 2013-03-04T22:10:50.723

Try the Java Preferences API to store user data like this.

Storing data in the application folder will be problematic (e.g., user might not have permission, application might be signed, etc). You can store a file in the user home directory, but most operating systems have a designated location to store user data (e.g., 'Application Support' on Mac, AppData on Windows, etc). Plus the user probably won't appreciate you cluttering up their home directory. You can create a properties file and handle storing it in the proper place yourself, but an easier solution would be to use the Preferences API which abstracts the pain of having to know where to write the file.

Here is an example:

import java.util.prefs.Preferences;

public class Test {
    public static final String DB_PROP = "user.selected.db.address";

    public static void main(String[] args) {
        Preferences prefs = Preferences.userNodeForPackage(Test.class);
        prefs.put(DB_PROP, "foo");
        String dbAddress = prefs.get(DB_PROP, null);
        System.out.println(dbAddress);
    }
}

score 0 · Answer 4 · answered Mar 04 '13 at 21:27

0

Here's what worked for me. I simply used the path System.getProperty("user.home") as my file's location. This is operating system neutral.

answered Mar 04 '13 at 21:27

Joel Christophel

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It will work across operating systems, but is not friendly to the user. Please see my updated answer for another option. – martinez314 Mar 04 '13 at 22:05

Save information from Java application

4 Answers4