How to check if a bluetooth device is connected with Android device?

This example demonstrates how do I check if a Bluetooth device is connected with android device.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:padding="16dp"
   android:orientation="vertical" >
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textSize="24sp"
      android:textStyle="bold"
      android:text="Open bluetooth setting from your own device and check for better results."/>
</LinearLayout>

Step 3 − Add the following code to src/MainActivity.java

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.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      IntentFilter filter = new IntentFilter();
      filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
      filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
      filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
      this.registerReceiver(broadcastReceiver, filter);
   }
   private final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
      BluetoothDevice device;
      @Override
      public void onReceive(Context context, Intent intent) {
         String action = intent.getAction();
         device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
         if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
            Toast.makeText(getApplicationContext(), "Device is now Connected",    Toast.LENGTH_SHORT).show();
         } else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
               Toast.makeText(getApplicationContext(), "Device is disconnected",       Toast.LENGTH_SHORT).show();
         }
      }
   };
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.com.sample">
   <uses-permission android:name="android.permission.BLUETOOTH" />
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from the android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

Azhar

Published on 30-Oct-2019 14:52:20