找到重复的蓝牙设备。 我在这里双倍浸泡？ 也能够更新recyclerview

我试图建立一个Android应用程序，扫描蓝牙设备，并将其添加到recyclerview。 当我试图清除我的arraylist并添加新的数据，在适配器我结束了一个空的arraylist。 当我不清除列表我结束了包含每个设备两次这样的列表： [**:71:9F:B6:59:**, **:71:9F:B6:59:**]在logcat中。 我也认为我在这里与我的notifydatasetchanged调用这里做错了什么，因为什么都不显示在我的recyclerview。 我敢肯定，这是简单的，我失踪，但我不能看到它。 我发布我的主要活动的代码，也是我的recyclerview.adapter，希望有人能指出我的问题。 提前致谢。 这是我的主要活动：

 public class ToofActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener { private static final String TAG = "ToofActivity"; private static final int REQUEST_COARSE_LOCATION = 222; private static BluetoothAdapter btAdapter; private TextView mStatusLabel; private Switch mStatusSwitch; private ProgressBar mProgressBar; private RecyclerView mDeviceRecylcer; private static ArrayList<BluetoothDevice> mDevices = new ArrayList<>(); private DeviceAdapter mAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_toof); checkLocationPermission(); btAdapter = BluetoothAdapter.getDefaultAdapter(); mStatusLabel = (TextView) findViewById(R.id.status_view); mStatusSwitch = (Switch) findViewById(R.id.status_switch); mStatusSwitch.setChecked(btAdapter.isEnabled()); mStatusSwitch.setOnCheckedChangeListener(this); mProgressBar = (ProgressBar) findViewById(R.id.search_progress_bar); mDeviceRecylcer = (RecyclerView) findViewById(R.id.device_recycler); mDeviceRecylcer.setLayoutManager(new LinearLayoutManager(this)); mAdapter = new DeviceAdapter(mDevices, getApplicationContext()); mDeviceRecylcer.setAdapter(mAdapter); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.options_menu, menu); return super.onCreateOptionsMenu(menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.searchOption: DiscoveryTask discovery = new DiscoveryTask(btAdapter, this, mDevices, mProgressBar); discovery.setOnCompleteListener(new DiscoveryTask.OnCompletedListener() { @Override public void onComplete() { Log.d(TAG, "devices found : " + mDevices.toString()); mAdapter.updateItems(mDevices); } }); discovery.execute((Void) null); break; } return true; } @Override public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { if (isChecked) { btAdapter.enable(); mStatusLabel.setText("Active"); } else { btAdapter.disable(); mStatusLabel.setText("Inactive"); } } public static void setDeviceList(ArrayList<BluetoothDevice> deviceList) { mDevices = deviceList; } protected void checkLocationPermission() { if (this.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) { ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, REQUEST_COARSE_LOCATION); } } @Override public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) { switch (requestCode) { case REQUEST_COARSE_LOCATION: { if (grantResults.length <= 0 || grantResults[0] != PackageManager.PERMISSION_GRANTED) { checkLocationPermission(); break; } } } } } 

也是我的适配器类写在kotlin而不是java：

 class DeviceAdapter(val mDevices: ArrayList<BluetoothDevice>, val mContext : Context) : RecyclerView.Adapter<DeviceAdapter.DeviceHolder>(){ fun updateItems(list: ArrayList<BluetoothDevice>){ //mDevices.clear() mDevices.addAll(list) Log.d(TAG, "updating items : $mDevices") notifyDataSetChanged() } override fun onBindViewHolder(holder: DeviceHolder, position: Int) { holder.bindItems(mDevices.get(position)) } override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): DeviceHolder?{ //return is not to be NULL! val v = LayoutInflater.from(mContext).inflate(R.layout.device_item, parent, false) return DeviceHolder(v) } override fun getItemCount(): Int { return mDevices.size } inner class DeviceHolder(itemView: View) : RecyclerView.ViewHolder(itemView){ val nameView = itemView.findViewById(R.id.nameView) as TextView val addrView = itemView.findViewById(R.id.addressView) as TextView fun bindItems(btDevice: BluetoothDevice){ nameView.text = btDevice.name addrView.text = btDevice.address } } companion object { val TAG = "DeviceAdapter" } } 

Answer 1

问题是DeviceAdapter.mDevices和ToofActivity.mDevices是同一个对象。 所以当你清除它时，它变成空的，当你mDevices.addAll(mDevices) ，元素加倍。

从DeviceAdapter的构造函数参数中删除mDevices 。 在DeviceAdapter为它创建一个新的ArrayList 。