How to generate and store UUID locally on the user's phone?

I want to generate a UUID for the user and store it locally for using it during transmission of a Bluetooth Low Energy Signal.

Here's what I have tried:

Class for generating UUID for a user:

public class Installation{
private static String uniqueID = null;
private static final String PREF_UNIQUE_ID = "PREF_UNIQUE_ID";
public synchronized static String id(Context context) {
if (uniqueID == null) {
SharedPreferences sharedPrefs = context.getSharedPreferences(
PREF_UNIQUE_ID, Context.MODE_PRIVATE);
uniqueID = sharedPrefs.getString(PREF_UNIQUE_ID, null);
if (uniqueID == null) {
uniqueID = UUID.randomUUID().toString();
SharedPreferences.Editor editor = sharedPrefs.edit();
editor.putString(PREF_UNIQUE_ID, uniqueID);
editor.commit();
}
}    return uniqueID;
}
}

And here's the transmission code:

AdvertisingSetParameters parameters = new AdvertisingSetParameters.Builder()
.setInterval(advInterval)
.setTxPowerLevel(AdvertisingSetParameters.TX_POWER_MEDIUM)
.setConnectable(true)
.build();
deviceId = Installation.id ( this );
ParcelUuid pUuid = new ParcelUuid( UUID.fromString( deviceId ) );
AdvertiseData data = new AdvertiseData.Builder()
.addServiceUuid( pUuid )
.addServiceData( pUuid, "Data".getBytes( StandardCharsets.UTF_8 ) )
.build();
mAdvertiseCallback = new AdvertisingSetCallback () {
@Override
public void onAdvertisingSetStarted(AdvertisingSet advertisingSet,
int txPower,
int status) {
super.onAdvertisingSetStarted (advertisingSet, txPower, status);
count += 1 ;
mPacketsSent.setText ( count );
Toast.makeText( BluetoothActivity.this, "Started "+ status, Toast.LENGTH_LONG ).show ();
}

But I keep getting the errors:
Unknown bits set in runtime_flags: 0x28000

2020-08-03 12:30:52.871 31040-31040/? E/PswFrameworkFactory:  Reflect exception getInstance: java.lang.ClassNotFoundException: com.oppo.common.PswFrameworkFactoryImpl
2020-08-03 12:30:52.990 31040-31076/com.example.beacondistance E/Perf: Fail to get file list com.example.beacondistance
2020-08-03 12:30:52.990 31040-31076/com.example.beacondistance E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array

What am I doing wrong in the above block of code? It doesn't matter to me that the UUID would change per installation I just want it to be generated and be advertised in the signal.

In case of Bluetooth LE Advertising, you can send 31 bytes of data. If you add Tx power/Service UUID/Service data, that will consume spaces also. And it may also a hardware problem, so I recommend that you also test on different devices. I made a Contact Tracer app, so I know the situations you may face. I am sharing the advertising code worked for me.

private void advertise() {
advertiser = bluetoothAdapter.getBluetoothLeAdvertiser();
AdvertiseSettings settings = new AdvertiseSettings.Builder()
.setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_LOW_LATENCY)
.setTxPowerLevel(AdvertiseSettings.ADVERTISE_TX_POWER_HIGH)
.setConnectable(false)
.setTimeout(0)
.build();
ParcelUuid pUuid = new ParcelUuid(your_uuid);
final AdvertiseData data = new AdvertiseData.Builder()
.setIncludeDeviceName(false)
.setIncludeTxPowerLevel(false)
.addServiceUuid(pUuid)
.addManufacturerData(DATA_MARKER, DATA_VALUE)
.build();
advertiser.startAdvertising( settings, data, advertisingCallback );
}

Few things I want to mention that, when you added the UUID, you used 16 bytes already. So for DATA_MARKER and DATA_VALUE you can chose int, that will not exceed the packet size.