How can I backup SharedPreferences to SD card?

Question

I saw in a lot of places that it\'s a problem to copy the SharedPreferences file to the sd card because every manufacturer place it somewhere else.

I want to backup

Answer 1

An alternative to using ObjectOutputStream/ObjectInputStream is to add the XmlUtils.java and FastXmlSerializer.java files from the Android source to your project, and then use XmlUtils.writeMapXml() and XmlUtils.readMapXml():

boolean res = false;
FileOutputStream output = null;
try {
    output = new FileOutputStream(dst);
    SharedPreferences pref = 
                        getSharedPreferences(prefName, MODE_PRIVATE);
    XmlUtils.writeMapXml(pref.getAll(), output);

    res = true;
    }

.....

FileInputStream input = null;
try {
    input = new FileInputStream(src);
        Editor prefEdit = getSharedPreferences(prefName, MODE_PRIVATE).edit();
        prefEdit.clear();
        Map entries = XmlUtils.readMapXml(input);
        for (Entry entry : entries.entrySet()) {
            putObject(prefEdit, entry.getKey(), entry.getValue());
        }
    }

.....

static SharedPreferences.Editor putObject(final SharedPreferences.Editor edit,
                                          final String key, final Object val) {
    if (val instanceof Boolean)
        return edit.putBoolean(key, ((Boolean)val).booleanValue());
    else if (val instanceof Float)
        return edit.putFloat(key, ((Float)val).floatValue());
    else if (val instanceof Integer)
        return edit.putInt(key, ((Integer)val).intValue());
    else if (val instanceof Long)
        return edit.putLong(key, ((Long)val).longValue());
    else if (val instanceof String)
        return edit.putString(key, ((String)val));

    return edit;
}

The storage format will then be the same XML as is used to store the SharedPreferences.