CODEWITHSUNDEEP
android
samvel1024
samvel1024

Reputation: 1163

Android get data of previous version of the application

Maybe my question has been asked before, but I couldn't find the proper keyword for searching this.

So I was assigned to develop an update of an application which will be uploaded soon. But I have one big problem. The users who have already installed the previous version may have some data which may be lost when updated. The data is stored in this location

/data/data/app_package_name/shared_prefs/data.xml

I need to browse the text inside the data.xml in order to get required fragments for using them in the new version. How can I check if the application was installed previously and only then read the user data only once when installing the update?

Upvotes: 0

Views: 253

Answers (1)

Wildroid
Wildroid

Reputation: 864

In your main activity:

    private static final String PRIVATE_PREF = "MainActivity";
    private static final String VERSION_KEY = "1";

In onCreate():

    init();

init() method:

private void init() {
        SharedPreferences sharedPref    = getSharedPreferences(PRIVATE_PREF, Context.MODE_PRIVATE);
        int currentVersionNumber        = 0;

        int savedVersionNumber          = sharedPref.getInt(VERSION_KEY, 0);

        try {
                PackageInfo pi          = getPackageManager().getPackageInfo(getPackageName(), 0);
            currentVersionNumber    = pi.versionCode;
            } catch (Exception e) {}


            if (currentVersionNumber > savedVersionNumber) {            
                readData();

                Editor editor   = sharedPref.edit();

                editor.putInt(VERSION_KEY, currentVersionNumber);
                editor.commit();
            }
    }

readData() method - something like:

    private void readData() {
StringBuilder sb = new StringBuilder();
        try{
            BufferedReader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
            is.close();
        } catch(OutOfMemoryError om){
            om.printStackTrace();
        } catch(Exception ex){
            ex.printStackTrace();
        }
        String result = sb.toString();
}

Make sure you change the VERSION_KEY when you release new app version.

For parsing XML, refer to tutorial

Upvotes: 1

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