Nsryjdtyk

I'm creating e bill printing application for Android mobile devices. I have successfully connected application and small Bluetooth POS printer. I can also print a bill through this.

I have used fragments for this application and all fragments generating through main activity.

My question is, if I change the fragment and press the print button it will ask to connect with printer again. I need to avoid that process, because once user hit the print button in the previous fragment (this works if user print something using that fragment, otherwise it should ask here to connect with printer) he/she is already connected to a printer.

The problem occurs here when I enter the new fragment, then that fragment creates a new object for handler, I need to put that handler as a singleton. This handler is used to connect with printer through Bluetooth. I have tried a few solutions, but I was failed. Is there any way to do this. Please help me to find a better solution for this problem. Thanks in advance.

here is the code --
Handler and fragment's onCreateView,

private final Handler mHandler = new Handler() {

        @Override

        public void handleMessage(Message msg) {

            switch (msg.what) {

                case BluetoothService.MESSAGE_STATE_CHANGE:

                    switch (msg.arg1) {

                        case BluetoothService.STATE_CONNECTED:   //������

                            Toast.makeText(getContext(), "Connect successful",

                                    Toast.LENGTH_SHORT).show();

                            isDeviceConnected = true;



//                            updateConnectBtn();

//                            btnClose.setEnabled(true);

//                            btnSendDraw.setEnabled(true);

                            Log.v("Pasindu", "Connected!");

                            break;

                        case BluetoothService.STATE_CONNECTING:  //��������

                            Log.d("��������", "��������.....");

                            break;

                        case BluetoothService.STATE_LISTEN:     //�������ӵĵ���

                        case BluetoothService.STATE_NONE:

                            Log.d("��������", "�ȴ�����.....");

                            break;

                    }

                    break;

                case BluetoothService.MESSAGE_CONNECTION_LOST:    //�����ѶϿ�����

                    Toast.makeText(getContext(), "Device connection was lost",

                            Toast.LENGTH_SHORT).show();

                    isDeviceConnected = false;

//                    btnClose.setEnabled(false);

//                    btnSendDraw.setEnabled(false);

                    break;

                case BluetoothService.MESSAGE_UNABLE_CONNECT:     //�޷������豸

                    Toast.makeText(getContext(), "Unable to connect device",

                            Toast.LENGTH_SHORT).show();

                    break;

            }

        }



    }; 





 @Override

    public View onCreateView(LayoutInflater inflater, ViewGroup container,

                             Bundle savedInstanceState) {

        // Inflate the layout for this fragment

        View view = inflater.inflate(R.layout.data_fragment, container, false);

        btn_proceed = (Button) view.findViewById(R.id.btn_proceed);

        mService = new BluetoothService(getContext(), mHandler);

        cmd = new byte[3];

        isDeviceConnected = ((MainActivity)this.getActivity()).isDeviceConnected;



        btn_proceed.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                print();

            }

        });

        return view;

    }