Show version info only once on application start in Android App

I´d like to show a simple information dialog with an Ok-Button, about whats new in this version, b开发者_高级运维ut it should show only at the first start. Whats the best way to implement this ?

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I would (and have) used a SharedPreferences with a boolean or int value. Simply check if the last version is older than the current version and update the int. Here's a nice little snipit.

//check to see if we need to show whats new or not
        SharedPreferences config = getSharedPreferences(MY_PREFS_STRING, 0);
        int lastVersion = config.getInt(KEY_VERSION, -1);
        if(currentVersion > lastVersion ){
showDialog(id);
//set this as lastVersion
        }

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A number of solutions are documented here:

What is SharedPreferences in Android?

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with a boolean variable stored somewhere : preferences, DB, SD card, ..