CODEWITHSUNDEEP
javapreferences
a113nw
a113nw

Reputation: 1412

copy java preferences file for specific java app

I run a java application like this:

java --cp libs.jar MyClass myconfigfile

After a normal shutdown, the app will remember the values I had in numerous text fields and checkboxes. I'm told that 'last state' is kept in java preferences. I want to grab my last state from one computer and bring it over to another. Is there a way to do this?

I'm using Ubuntu 12.04.

Upvotes: 0

Views: 293

Answers (2)

DirkyJerky
DirkyJerky

Reputation: 1168

Regardless if your program is a class or a jar, one of the most portable methods is to just have a config file at the root of your project.

Example:

// Makes a file at the root of your project, and the name starts with a period so its hidden by the system.
File stateFile = new File(".lastState");
// Creates a file IF it doesn't exist already
stateFile.createNewFile();

// Do stuff

// Then save stuff to the file

Psuedo code for writing options:

PrintStream out = new PrintStream(stateFile);

for(Option option : yourList.options()) {
    // Print the option name, a Unit seperator char, the status of the option, and a Group seperator char
    out.print(option.getName() + '\x1F' + option.status() + '\x1D');
}

Psuedo code for reading options:

private boolean readOptionsFromStateFile(Map<String, Option> mapOfOptionNamesToOption) {
     Scanner in = new Scanner(stateFile);
     in.setDelimiter("\\x1D"); // Set the delimiter to the group seperator
     while(in.hasNext()) {
         String temp = in.next();
         if(temp == "") return;
         String[] keyValues = temp.split("\x1F"); // Split at the unit seperator
         if(keyValues.length != 2) {
             return false;
         }
         Option curOption = mapOfOptionNamesToOption.get(keyValues[0]);
         if(curOption != null) {
             curOption.setStatus(keyValues[1]);
         } else {
             return false;
         }
     }
     return true;
}

Upvotes: 0

martinez314
martinez314

Reputation: 12332

Based on the limited information you provide, it sounds like the application is using the Java Preferences API. In this case, where the data is actually stored is OS-dependent. In Windows, it's in the Registry. Linux and OS X, I'm not sure. That is, the data is not likely stored in a single properties file somewhere from which you can just copy it.

If you have access to the code, you can export the Preferences object to a file though.

FileOutputStream output = new FileOutputStream("myPrefs.xml");
myPrefs.exportSubtree(output);

Edit: Looks like in Linux you may find the info in one of these two places:

~/.java/.userPrefs
/etc/.java/.systemPrefs

Upvotes: 1

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