simple decode base64 android java

private static String decode(String data) {
        try {
            byte[] decode = android.util.Base64.decode(data, android.util.Base64.DEFAULT);
            return new String(decode);
        } catch (IllegalArgumentException e) {
            return null;
        }
    }

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penggunaan
String mangan = decode("Y2EtYXBwLXB1Yi0zOTQwMjU2MDk5OTQyNTQ0LzEwMzMxNzM3MTI=")
mInterstitialAd.setAdUnitId(mangan);

atau bisa juga
mInterstitialAd.setAdUnitId(decode("Y2EtYXBwLXB1Yi0zOTQwMjU2MDk5OTQyNTQ0LzEwMzMxNzM3MTI="));