Set the NTP server of your android device

android-set-ntp-server.md

tags	Android Android Things

Set the NTP server of your android device

Just use this command to set a server address to automatically sync your device time. ( ͡° ͜ʖ ͡°)✧

$ adb shell settings put global ntp_server <new-ntp-server>

Background

I have a Raspberry Pi 3 with Android Things installed on it. But the time is never synchronized...

After googling it, I found this piece of code in NtpTrustedTime.java

public class NtpTrustedTime implements TrustedTime {
    ...
    public static synchronized NtpTrustedTime getInstance(Context context) {
        if (sSingleton == null) {
            final Resources res = context.getResources();
            final ContentResolver resolver = context.getContentResolver();
            final String defaultServer = res.getString(
                    com.android.internal.R.string.config_ntpServer);
            final long defaultTimeout = res.getInteger(
                    com.android.internal.R.integer.config_ntpTimeout);
            final String secureServer = Settings.Global.getString(
                    resolver, Settings.Global.NTP_SERVER);
            final long timeout = Settings.Global.getLong(
                    resolver, Settings.Global.NTP_TIMEOUT, defaultTimeout);
            final String server = secureServer != null ? secureServer : defaultServer;
            sSingleton = new NtpTrustedTime(server, timeout);
            sContext = context;
        }
        return sSingleton;
    }
}

It shows that android tring to get NTP server from:

1. Settings.Global.NTP_SERVER first

2. Then com.android.internal.R.string.config_ntpServer

And the NTP server of my Android Things is time.android.com, that's why it dose not work (I'm in China...).

---

Fortunately, it is easy to set settings via adb:

$ adb shell settings put global ntp_server asia.pool.ntp.org

# test
$ adb shell settings get global ntp_server 
> asia.pool.ntp.org

🎉 CHEERS

Android 14 & higher natively support multiple NTP servers for redundancy.

I figured out how to put multiple NTP servers onto ntp_server after looking at NtpTrustedTime for like a day.
$ adb shell settings put global ntp_server "ntp://time.google.com'|'ntp://time.cloudflare.com'|'ntp://pool.ntp.org"

It is explained inside the documentation on how each server is separated however command line also uses the pipe character for commands so you have put it inside quote marks like this '|'

You can verify if your device support multiple NTP server using
$ adb shell cmd network_time_update_service force_refresh
&
$ adb shell cmd network_time_update_service dump