Why the device will connect again when we diconnect from device?

[berniechen]

I modified the nordic uart apk from this website

github.com/.../Android-nRF-UART

and I do some revising below

MainActivity.java:
if (action.equals(WearableService.ACTION_GATT_DISCONNECTED)) {
    runOnUiThread(new Runnable() {
     public void run() {
     Log.d(tAg, "UART_DISCONNECT_MSG");
     mState = UART_PROFILE_DISCONNECTED;
     //mService.close(); <--- I comment this
     }
     });
 }

When I disconnect from device, I can see log on my phone Xperia X compact (android 7.0)

BluetoothGatt: cancelOpen() - device: F1:C1:E2:24:ED:57
BluetoothGatt: onClientConnectionState() - status=0 clientIf=5 device=F1:C1:E2:24:ED:57
BluetoothGatt: onClientConnectionState() - status=0 clientIf=5 device=F1:C1:E2:24:ED:57
BluetoothGatt: discoverServices() - device: F1:C1:E2:24:ED:57
BluetoothGatt: onSearchComplete() = Device=F1:C1:E2:24:ED:57 Status=0
BluetoothGatt: setCharacteristicNotification() - uuid: 6e400003-b5a3-f393-e0a9-e50e24dcca9e enable: true

I find It will connect again after I disconnect from the device and then do discoverServi

ce and finally disconnect, why???? The workaround method is uncomment the mService.close() to release the resource when MainActivity.java gets DISCONNECT broadcast.

Below is the screen shot of my phone(we only revised UUID for UartService, there are no revising at Uart apk). When I disconnect from device at 10:18:45 and then reconnect at 10:18:47 and then send one command(this device automatically notify data to apk per 3 second) and then finally disconnect.

Another product we develop is below, because it will reconnect, so the button still show Disconnect, not Connect, and we can't change button state anymore, because it has disconnect, we can't send disconnect command to it.

below is operate null pointer.

[berniechen]

@Hung Bui: Hi, Sorry, I still do some revises about UUID. We are using google pixel phone( native android 7.1.1) instead of Xperia x compact. And I only revise the code below //public static final UUID RX_SERVICE_UUID = UUID.fromString("6e400001-b5a3-f393-e0a9-e50e24dcca9e"); public static final UUID RX_SERVICE_UUID = UUID.fromString("0000fe55-0000-1000-8000-00805f9b34fb");

//public static final UUID TX_CHAR_UUID = UUID.fromString("6e400003-b5a3-f393-e0a9-e50e24dcca9e");
public static final UUID TX_CHAR_UUID = UUID.fromString("00000001-1000-1000-8000-00805f9b34fb");

referenced from github.com/.../Android-nRF-UART

Then, I got the error message of application forced closed when I press the Disconnect button and result like picture third above. The result of I am listening logcat shows the root cause is the phone will reconnect from callback but we have executed mService.close() to release resource before.

I UartService: Connected to GATT server.
D BluetoothGatt: discoverServices() - device: E9:6A:37:30:9D:D9
D BtGatt.GattService: discoverServices() - address=E9:6A:37:30:9D:D9, connId=6