Question

我正在编写一个包含由viewpager包装的2个片段的应用程序。我试图获取蓝牙可用设备的列表，但列表视图永远不会改变这是我第一次使用片段。我希望你们能帮助我。提前致谢！

这是片段：

public class BluetoothDevicesFragment extends Fragment {
    private ListView mListView;
    private BluetoothListAdapter mAdapter;
    private ArrayList<String> mArray;
    private SwipeRefreshLayout mRefresh;
    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            //Finding devices
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                // Get the BluetoothDevice object from the Intent
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                // Add the name and address to an array adapter to show in a ListView
                //Snackbar.make(getView(), device.getName(), Snackbar.LENGTH_LONG).setAction("Action", null).show();
                mArray.add(device.getName() + "\n" + device.getAddress());
                mAdapter.notifyDataSetChanged();
            } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                mRefresh.setRefreshing(false);
                getActivity().unregisterReceiver(mReceiver);
            }
        }
    };

    public BluetoothDevicesFragment() {

    }

    public static BluetoothDevicesFragment newInstance() {

        Bundle args = new Bundle();

        BluetoothDevicesFragment fragment = new BluetoothDevicesFragment();
        fragment.setArguments(args);
        return fragment;
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_bluetooth, container, false);
        mListView = (ListView) rootView.findViewById(R.id.listviewB);
        mArray = new ArrayList<>();
        mAdapter = new BluetoothListAdapter(getContext(), R.layout.fragment_bluetooth, mArray);
        mListView.setAdapter(mAdapter);
        mRefresh = (SwipeRefreshLayout) rootView.findViewById(R.id.refresh);
        mRefresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
                getActivity().registerReceiver(mReceiver, filter);
                Bluetooth.bluetoothAdapter.cancelDiscovery();
                Bluetooth.bluetoothAdapter.startDiscovery();
            }
        });
        return rootView;
    }
}

Answer 1

您必须注册BroadcastReceiver才能接收活动

有两种方法可以做到这一点：

在清单文件中注册BroadcastReceiver

<receiver
android:name="com.pycitup.pyc.MyReceiver"
android:enabled="true"
android:exported="true" >
<intent-filter>
    <action android:name="com.pycitup.BroadcastReceiver" />
</intent-filter>

以编程方式注册BroadcastReceiver

IntentFilter filter = new IntentFilter("packagename.customclass");

MyReceiver myReceiver = new MyReceiver();
registerReceiver(myReceiver, filter);

在manifest.xml

中添加权限

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

不要忘记检查abaove的运行时权限

BroadcastReceiver从不在ViewPager中调用Fragment上的OnReceive

1 个答案: