Bluetooth

Bluetooth is a way to exchange data with other devices from wireless devices. Android provides Bluetooth APIs for doing many things, 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

With the help of the Bluetooth adapters category, we can do basic tasks such as starting a device search, ask the list of paired (bonded) devices, create a Bluetooth server watch screen to hear connection requests and more.

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 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:

<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.

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.

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;  

    }  

  

}