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Android Bluetooth Tutorial

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

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

<RelativeLayout xmlns:androclass="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" >

    <TextView android:text=""
     android:id="@+id/out" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content">
    </TextView>
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="30dp"
        android:layout_marginTop="49dp"
        android:text="TURN_ON" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button1"
        android:layout_below="@+id/button1"
        android:layout_marginTop="27dp"
        android:text="DISCOVERABLE" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button2"
        android:layout_below="@+id/button2"
        android:layout_marginTop="28dp"
        android:text="TURN_OFF" />

</RelativeLayout>

Provide Permission

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

    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

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

File: AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:androclass="http://schemas.android.com/apk/res/android"
    package="com.example.bluetooth"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="16" />

    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.bluetooth.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

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;
    }

}

download this android example

You need to run it on the real device (e.g. mobile) to test the application.

Next topics of android bluetooth tutorial:

android bluetooth list paired devices example

Next TopicAndroid Bluetooth List Paired Devices Example

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