Generating Device-Specific Serial Number [duplicate]

Answer 1

You can use Serial Number as a unique Identifier as they are availbalble in all devices.You should not use IMEI as a unique identifier as they are not abalibale in WIFI Tabs(tabs that do not have SIM Card Slot).

You can use

    try {
        Class c = Class.forName("android.os.SystemProperties");
        Method get = c.getMethod("get", String.class, String.class);
        serial = (String) get.invoke(c, "ril.serialnumber", "unknown");
    } catch (Exception ignored) {
    }