Android RecyclerView 仅在关闭并重新启动应用程序后显示项目

Question

将应用程序更新到 API 28 后，我的 RecyclerView 出现了奇怪的效果。我有一个搜索按钮，可以触发对我所在区域的 Wifi 设备的搜索。这些项目不再直接显示在列表中。我必须关闭并重新打开应用程序才能获得正确的显示。我有一个在按下按钮时应该显示的吐司。Toast 消息也仅在关闭和打开应用程序后显示。活动.kt   private fun setFloatingSearchButton() {        floating_button_discover_devices.setOnClickListener { view ->            Snackbar.make(view, "Search for new devices ...",                    Snackbar.LENGTH_SHORT).setAction("Action", null).show()            discoverDevices()            registerReceiver(mWifiReceiver, IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION))            mWifiManager!!.startScan()        }    }WifiAdapter.javapublic class WifiAdapter extends RecyclerView.Adapter<WifiAdapter.ViewHolder> {    private final int CONFIGURE_DEVICE_REQUEST_CODE = 0x00000001;    private static final String TAG = "WifiAdapter";    private List<DeviceWifiTo> wifis;    private Context context;    private Activity activity;    public WifiAdapter(List<DeviceWifiTo> wifis) {        this.wifis = wifis;    }    @Override    public WifiAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        context = parent.getContext();        activity = (Activity) context;        LayoutInflater inflater = LayoutInflater.from(context);        View wifiView = inflater.inflate(R.layout.item_wifi, parent, false);        return new WifiAdapter.ViewHolder(wifiView);    }    @Override    public void onBindViewHolder(WifiAdapter.ViewHolder holder, int position) {        DeviceWifiTo wifi = wifis.get(position);        Log.d(TAG, wifi.getSsid());        TextView wifiName = holder.wifiName;        wifiName.setText(wifi.getSsid());        CardView cardView = holder.cardView;        cardView.setOnClickListener(view -> {            Intent intent = new Intent(context, ConfigureDeviceActivity.class);            intent.putExtra("ssid", wifi.getSsid());            activity.startActivityForResult(intent, CONFIGURE_DEVICE_REQUEST_CODE);        });    }

Answer 1

layout manager之前设置为adapter，recycler view更新如下

private void createRecyclerView(List<DeviceWifiTo> list) {

   RecyclerView recyclerView = activity.findViewById(R.id.recycler_view_wifi);

   recyclerView.setLayoutManager(new LinearLayoutManager(activity.getApplicationContext()));

   WifiAdapter adapter = new WifiAdapter(list);

   recyclerView.setAdapter(adapter);

}

希望对您有帮助。

Answer 2

layoutmanager在设置之前尝试设置adapter




Answer 3

我猜你想在 recyclerView 中显示你的结果。您的搜索有回调方法吗？

您需要在该回调方法中调用notifyDataSetChanged()（设置结果然后调用notifyDataSetChanged()）

Answer 4

我在 kotlin 中遇到了类似的问题，只是因为没有添加notifyDataSetChanged()我设置数据的位置。