Android Bluetooth Scanner startDiscovery() showing nothing at the output

问题

Problem I am trying to create a bluetooth scanner , using android bluetooth API startDiscovery() method. I'm trying to show device list using list view,but the output dont show anything.

package com.example.shad.lucaa;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.ListView;
import android.widget.Switch;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    Button button;
    ListView scanListView;
    ArrayList<String> stringArrayList = new ArrayList<String>();
    ArrayAdapter<String> arrayAdapter;
    BluetoothAdapter myadapter = BluetoothAdapter.getDefaultAdapter();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = findViewById(R.id.scan);
        scanListView = findViewById(R.id.list);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                myadapter.startDiscovery();
            }
        });

        IntentFilter intentFilter = new IntentFilter((BluetoothDevice.ACTION_FOUND));
        registerReceiver(myReciver,intentFilter);
        arrayAdapter=new ArrayAdapter<String>(getApplicationContext(),android.R.layout.simple_list_item_1,stringArrayList);
        scanListView.setAdapter(arrayAdapter);
    }
        BroadcastReceiver myReciver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action=intent.getAction();
                if(BluetoothDevice.ACTION_FOUND.equals(action)){
                    BluetoothDevice device=intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    stringArrayList.add(device.getName());
                    arrayAdapter.notifyDataSetChanged();
                }
            }
        };
    }

My layout file

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:transitionGroup="true">


    <ListView
        android:id="@+id/list"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:layout_marginStart="0dp"
        android:layout_marginLeft="0dp"
        android:layout_marginTop="0dp"
        android:layout_marginEnd="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginBottom="0dp" />

    <Button
        android:id="@+id/scan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginStart="157dp"
        android:layout_marginLeft="157dp"
        android:text="Button" />


</RelativeLayout>

Is there any other method I can use for getting the list of all available bluetooth devices. Thanks is advance.

来源：https://stackoverflow.com/questions/61008192/android-bluetooth-scanner-startdiscovery-showing-nothing-at-the-output