MainActivity.java

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.Set;

public class MainActivity extends AppCompatActivity {
    Button Sync;
    ImageView search_bt;
    TextView ListTxt;
    ListView listview;

    private BluetoothAdapter BA;
    private Set<BluetoothDevice> pairedDevices;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Sync = findViewById(R.id.sync);
        search_bt = findViewById(R.id.search_bt);
        ListTxt = findViewById(R.id.ListTxt);
        listview = findViewById(R.id.listview);
        ListTxt.setText(getLocalBluetoothName());

        BA = BluetoothAdapter.getDefaultAdapter();
        if (BA == null) {
            Toast.makeText(this, "Bluetooth not supported", Toast.LENGTH_SHORT).show();
            finish();
        }
        else{

        }

        Sync.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                    list();

            }
        });

    }

    private void list() {
        pairedDevices = BA.getBondedDevices();

        ArrayList list = new ArrayList();

        for (BluetoothDevice bt : pairedDevices) {
            list.add(bt.getName());
        }
        Toast.makeText(this, "Showing Devices", Toast.LENGTH_SHORT).show();
        ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, list);
        listview.setAdapter(adapter);
    }

    public String getLocalBluetoothName() {
        if (BA == null) {
            BA = BluetoothAdapter.getDefaultAdapter();
        }
        String name = BA.getName();
        if (name == null){
            name = BA.getAddress();
        }
        return name;
    }
   
}