bluetoothleadvertiser | NewCircle Android Training : Application that broadcasts | Android library

A single advertisement packet is limited to about 23 data bytes so it does not have room for both manufacturer data and service data of the sizes you have in your example.

Try advertising both at the same time each in its own advertisement. Android devices support transmitting multiple advertisements simultaneously.

CoreBluetooth is not a format. It is a set of APIs on iOS. Using CoreBluetooth you can detect a variety of beacon formats with limitations:

• AltBeacon format can be detected only with the iOS app in the foreground
• Eddystone formats can be detected in the foreground and the background but is slower to detect in the background than iBeacon.
• iBeacon format cannot detected by CoreBluetooth. For that you must use CoreLocation.

To advertise in AltBeacon (detectable by core Bluetooth) use this code:

As it turns out, the data inside the string in .addServiceData is limited to only four characters. As soon as this is within this limit, the above code works fine for its intended purposes.

The reason the code shown causes a NullPointerException is because it is trying to access currentAdvertisingSet[0] before you have assigned a value to that array element.

When the code initializes it with final AdvertisingSet[] currentAdvertisingSet = new AdvertisingSet[1]; then the contents of the array is initialized with each element set to null. The code doesn't initialize currentAdvertisingSet[0] to a non-null value until the AdvertisingSetCallback executes. This is asynchronous, and will happen in at some time after the call to advertiser.startAdvertisingSet(...).

The problem is that this callback hasn't happened yet when the next line currentAdvertisingSet[0].setAdvertisingData(...) executes a few microseconds later. When it executes, the currentAdvertisingSet[0] element has not yet been initialized -- it is still null. That is why the code crashes.

To fix this, you must wait to use currentAdvertisingSet[0] until it has been initialized. You can certainly add a check like if (currentAdvertisingSet[0] != null) to prevent the crash, but in the code shown this will never be true, so the code will never execute.

Ultimately, you will need to move the code that alters the advertising set so that it executes at a later time. You could put this code inside the callback, but that might not make sense for your use case -- there is likely no point in starting advertising then immediately changing it to something else.

Scan use following code, can get the right result:

When AdvertiseSettings.Builder#setTimeout() sets the value of the advertising time to 0, the time limit will be disabled and the advertising is always work unless BluetoothLeAdvertiser#stopAdvertising() is called.

More information please see: https://developer.android.com/reference/android/bluetooth/le/AdvertiseSettings.Builder.html#setTimeout(int)

It looks to me like you are adding pUuid to the advertisement data twice. Once by itself and a second time with the data "D". BLE advertisements only have room for 1 UUID. Try eliminating that first call to:

Even with Bluetooth Low Energy being available in Android API level 18, you will not be able to use an Android phone in peripheral mode with API level lower than 21.

As seen in Android Lolipop release notes:

Android 4.3 introduced platform support for Bluetooth Low Energy (Bluetooth LE) in the central role. In Android 5.0, an Android device can now act as a Bluetooth LE peripheral device.

Also, not all Android devices that have Lollipop support the peripheral mode. This list shows what device models are able to transmit as the server.

You are able to use your app as the client side, there is a code example in the Android Bluetooth Low Energy documentation page.

Use Foreground service with persistent notification. Your service will be keep on running.