Bluetooth is a way to exchange data with other devices wirelessly. Android provides Bluetooth API to perform several tasks such as:

  • scan bluetooth devices
  • connect and transfer data from and to other devices
  • manage multiple connections etc.

Android Bluetooth API

The android.bluetooth package provides a lot of interfaces classes to work with bluetooth such as:

  • BluetoothAdapter
  • BluetoothDevice
  • BluetoothSocket
  • BluetoothServerSocket
  • BluetoothClass
  • BluetoothProfile
  • BluetoothProfile.ServiceListener
  • BluetoothHeadset
  • BluetoothA2dp
  • BluetoothHealth
  • BluetoothHealthCallback
  • BluetoothHealthAppConfiguration

android-preferences-example

BluetoothAdapter class

By the help of BluetoothAdapter class, we can perform fundamental tasks such as initiate device discovery, query a list of paired (bonded) devices, create a BluetoothServerSocket instance to listen for connection requests etc.

Constants of BluetoothAdapter class

BluetoothAdapter class provides many constants. Some of them are as follows:

  • String ACTION_REQUEST_ENABLE
  • String ACTION_REQUEST_DISCOVERABLE
  • String ACTION_DISCOVERY_STARTED
  • String ACTION_DISCOVERY_FINISHED

Methods of BluetoothAdapter class

Commonly used methods of BluetoothAdapter class are as follows:

  • static synchronized BluetoothAdapter getDefaultAdapter() returns the instance of BluetoothAdapter.
  • boolean enable() enables the bluetooth adapter if it is disabled.
  • boolean isEnabled() returns true if the bluetooth adapter is enabled.
  • boolean disable() disables the bluetooth adapter if it is enabled.
  • String getName() returns the name of the bluetooth adapter.
  • boolean setName(String name) changes the bluetooth name.
  • int getState() returns the current state of the local bluetooth adapter.
  • Set<BluetoothDevice> getBondedDevices() returns a set of paired (bonded) BluetoothDevice objects.
  • boolean startDiscovery() starts the discovery process.

Android Bluetooth Example: enable, disable and make discovrable bluetooth programmatically

You need to write few lines of code only, to enable or disable the bluetooth.

activity_main.xml

Drag one textview and three buttons from the pallete, now the activity_main.xml file will like this:

File: activity_main.xml

Provide Permission

You need to provide following permissions in AndroidManifest.xml file.

The full code of AndroidManifest.xml file is given below.

File: AndroidManifest.xml

Activity class

Let’s write the code to enable, disable and make bluetooth discoverable.

File: MainActivity.java
package com.example.bluetooth;  
import android.os.Bundle;  
import android.app.Activity;  
import android.view.Menu;  
import android.app.Activity;  
import android.bluetooth.BluetoothAdapter;  
import android.content.Context;  
import android.content.Intent;  
import android.os.Bundle;  
import android.util.Log;  
import android.view.View;  
import android.widget.Button;  
import android.widget.TextView;  
import android.widget.Toast;  
  
public class MainActivity extends Activity {  
      private static final int REQUEST_ENABLE_BT = 0;  
      private static final int REQUEST_DISCOVERABLE_BT = 0;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
    final TextView out=(TextView)findViewById(R.id.out);  
    final Button button1 = (Button) findViewById(R.id.button1);  
    final Button button2 = (Button) findViewById(R.id.button2);  
    final Button button3 = (Button) findViewById(R.id.button3);  
    final BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();  
    if (mBluetoothAdapter == null) {  
       out.append("device not supported");  
    }  
    button1.setOnClickListener(new View.OnClickListener() {  
        public void onClick(View v) {  
            if (!mBluetoothAdapter.isEnabled()) {  
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);  
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);  
            }  
        }  
    });  
    button2.setOnClickListener(new View.OnClickListener() {  
     @Override  
        public void onClick(View arg0) {  
            if (!mBluetoothAdapter.isDiscovering()) {  
                  //out.append("MAKING YOUR DEVICE DISCOVERABLE");  
                   Toast.makeText(getApplicationContext(), "MAKING YOUR DEVICE DISCOVERABLE",  
             Toast.LENGTH_LONG);  
  
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);  
                startActivityForResult(enableBtIntent, REQUEST_DISCOVERABLE_BT);  
                    
            }  
        }  
    });  
    button3.setOnClickListener(new View.OnClickListener() {  
        @Override  
        public void onClick(View arg0) {     
            mBluetoothAdapter.disable();  
            //out.append("TURN_OFF BLUETOOTH");  
            Toast.makeText(getApplicationContext(), "TURNING_OFF BLUETOOTH", Toast.LENGTH_LONG);  
           
            }  
    });  
}  
  
    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.activity_main, menu);  
        return true;  
    }  
  
}