Hello everybody,
I am not completely new to Android development, but for a few days now I have been trying to develop a Bluetooth app that can scan more devices like in my mobile phone but through my app. All tutorials that I have found so far do not work at all.
I am already posting my code from the android studio. I can list paired devices, but the scan cannot.
If someone has a good experience with Bluetooth here, I ask them for help. I thank you in advance
Java
package cm.rulan.distcovid.ui.home;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProvider;
import java.util.ArrayList;
import java.util.Set;
import cm.rulan.distcovid.R;
public class HomeFragment extends Fragment {
private static final String TAG = "Home";
private static final int REQUEST_ENABLE_BT = 1;
private static final int REQUEST_DISCOVERABLE_BT = 0;
Set<BluetoothDevice> pairedDevices;
private HomeViewModel homeViewModel;
private BluetoothAdapter bluethoothadapter;
private Button btnpairedDev, btnscan;
private ListView pairedDev;
private ArrayList list;
private ArrayList btdevnew;
private TextView tview;
private ProgressDialog mProgressDlg;
IntentFilter filter ;
BroadcastReceiver mReceiver ;
public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
homeViewModel = new ViewModelProvider(this).get(HomeViewModel.class);
View root = inflater.inflate(R.layout.fragment_home, container, false);
homeViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
@Override
public void onChanged(@Nullable String s) {
//textView.setText(s);
}
});
pairedDev = root.findViewById(R.id.listView);
list = new ArrayList<>();
btdevnew = new ArrayList<>();
tview = root.findViewById(R.id.textView);
btnpairedDev = root.findViewById(R.id.list);
btnscan = root.findViewById(R.id.scanBT);
mProgressDlg = new ProgressDialog(getContext());
mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
switch (action) {
case BluetoothAdapter.ACTION_DISCOVERY_STARTED:
mProgressDlg = new ProgressDialog(getContext());
mProgressDlg.setTitle(getContext().getString(R.string.searchForNewBluetoothDevices_titel));
mProgressDlg.setMessage(getContext().getString(R.string.searchForNewBluetoothDevices_msg));
mProgressDlg.setIndeterminate(true);
mProgressDlg.show();
break;
case BluetoothAdapter.ACTION_DISCOVERY_FINISHED:
mProgressDlg.cancel();
//activity.setFoundLabel();
break;
case BluetoothDevice.ACTION_FOUND:
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
final ArrayAdapter mNewDevicesArrayAdapter = new ArrayAdapter<String>(getContext(), R.layout.device_adapter_view);
mNewDevicesArrayAdapter.add(device);
pairedDev.setAdapter(mNewDevicesArrayAdapter);
Log.d(TAG, "device" +device);
break;
}
}
};
bluethoothadapter = BluetoothAdapter.getDefaultAdapter();
if (bluethoothadapter == null) {
// Device doesn't support Bluetooth
AlertDialog.Builder dialbuild = new AlertDialog.Builder(getContext());
dialbuild.setTitle("Nicht Kompatibel")
.setMessage("Your phone does not support Bluetooth")
.setPositiveButton("Exit", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
System.exit(0);
}
})
.setIcon(android.R.drawable.ic_dialog_alert)
.show();
}
if (!bluethoothadapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
} else {
Toast.makeText(this.getContext(), "Bluetooth is already On", Toast.LENGTH_SHORT).show();
}
if (!getContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(getContext(), R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
getActivity().finish();
}
return root;
}
@Override
public void onPause() {
if (bluethoothadapter != null) {
if (bluethoothadapter.isDiscovering()) {
bluethoothadapter.cancelDiscovery();
}
}
super.onPause();
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == REQUEST_ENABLE_BT)
{
if (resultCode == 0)
{
// If the resultCode is 0, the user selected "No" when prompt to
// allow the app to enable bluetooth.
// You may want to display a dialog explaining what would happen if
// the user doesn't enable bluetooth.
Toast.makeText(getContext(), "The user decided to deny bluetooth access", Toast.LENGTH_LONG).show();
}
else
Log.i(TAG, "User allowed bluetooth access!");
}
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//listPairedDevices();
btnpairedDev.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
listPairedDevices();
}
});
btnscan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ScanBluetoothDevices();
//scanLeDevice(true);
}
});
}
public void listPairedDevices() {
pairedDevices = bluethoothadapter.getBondedDevices();
if (pairedDevices.size() > 0) {
// Es gibt gekoppelte Geräte. Gib den name und adresse
// von jedem gekoppelten Gerät.
for (BluetoothDevice device : pairedDevices) {
String deviceName = device.getName(); // device Name
String deviceHardwareAddress = device.getAddress(); // MAC address
list.add(deviceName + "\t" + "\t" + deviceHardwareAddress);
Log.d("Device Name: ", "deviceName " + deviceName);
Log.d("Device Hardwareaddr: ", "deviceHardwareAdresse " + deviceHardwareAddress);
Toast.makeText(this.getContext(), "Showing Paired Devices", Toast.LENGTH_SHORT).show();
final ArrayAdapter adapter = new ArrayAdapter(this.getContext(), android.R.layout.simple_list_item_1, list);
pairedDev.setAdapter(adapter);
}
}
}
private void ScanBluetoothDevices() {
// If we're already discovering, stop it
if (bluethoothadapter.isDiscovering()) {
bluethoothadapter.cancelDiscovery();
} else {
// Request discover from BluetoothAdapter
// Create a BroadcastReceiver for ACTION_FOUND.
//discovery starts, we can show progress dialog or perform
//other tasks
filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.getActivity().registerReceiver(mReceiver, filter);
bluethoothadapter.startDiscovery();
}
}
}
After the execution of the program, by pressing the scan button we have this output:
D / ViewRootImpl @ ef507c7 [MainActivity]: ViewPostIme pointer 0
D / ViewRootImpl @ ef507c7 [MainActivity]: ViewPostIme pointer 1
D / BluetoothAdapter: startDiscovery
W / libEGL: EGLNativeWindowType 0x78f6244250 disconnect failed
D / ViewRootImpl @ eb5ee08 [Toast]: dispatchDetachedFromWindow
D / InputTransport: Input channel destroyed: 'b8fe85f', fd = 73s
it says startdiscovery after there is nothing