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我正在嘗試構建一個應用程序，該應用程序可以掃描藍牙設備並在回收站中顯示它們。我正在編寫一些使用java和kotlin中的一些應用程序的應用程序。出於某種原因，我的recyclerview項目不可見。有人請幫我找到我正在犯的錯誤。我發佈了我的活動代碼和我的回收商視圖。澄清我的問題。發現成功，找到了設備，並且我的適配器中的所有繼承方法似乎都被調用。我將日誌消息放入其中，並且在回收站視圖中仍然看不到任何內容。爲什麼沒有出現？這裏是我的活動java寫的：android java/kotlin recyclerview項目不可見
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);
mStatusLabel.setText(btAdapter.isEnabled() ? "Active" : "Inactive");
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(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, mProgressBar);
discovery.setOnCompleteListener(new DiscoveryTask.OnCompletedListener() {
@Override
public void onComplete() {
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.clear();
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;
}
}
}
}
}
，這裏是我的recyclerview寫在科特林代碼：
class DeviceAdapter(val mContext : Context) : RecyclerView.Adapter<DeviceAdapter.DeviceHolder>(){
val mDevices = ArrayList<BluetoothDevice>()
fun updateItems(list: ArrayList<BluetoothDevice>){
mDevices.clear()
mDevices.addAll(list)
Log.d(TAG, "updating items : $mDevices")
notifyDataSetChanged()
}
override fun onBindViewHolder(holder: DeviceHolder, position: Int) {
Log.d(TAG, "onBindViewHolder called!")
holder.bindItems(mDevices.get(position))
}
override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): DeviceHolder{
Log.d(TAG, "onCreateViewHolder called!")
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){
Log.d(TAG, "holder created!")
nameView.text = btDevice.name
addrView.text = btDevice.address
}
}
companion object {
val TAG = "DeviceAdapter"
}
}
謝謝你對我的幫助。