Author: Preetha S

Bluetooth Printer In Android

1 Open Android Studio.
 2 Go to File => New => New Project. Write application name . Then, check Include Kotlin Support and click next button.
 3Select minimum SDK you need. However, we have selected 17 as minimum SDK. Then, click next button
 4 Then, select Empty Activity => click next => click finish.
 5 You will get a newly created project successfully if you have followed steps properly.





Main.java





        import java.io.IOException;
        import java.io.OutputStream;
        import java.nio.ByteBuffer;
        import java.util.Set;
        import java.util.UUID;

        import android.app.Activity;
        import android.app.ProgressDialog;
        import android.bluetooth.BluetoothAdapter;
        import android.bluetooth.BluetoothDevice;
        import android.bluetooth.BluetoothSocket;
        import android.content.Intent;
        import android.os.Bundle;
        import android.os.Handler;
        import android.os.Message;
        import android.util.Log;
        import android.view.View;
        import android.view.Window;
        import android.view.WindowManager;
        import android.widget.Button;
        import android.widget.Toast;

        public class Main extends Activity implements Runnable {
            protected static final String TAG = "TAG";
            private static final int REQUEST_CONNECT_DEVICE = 1;
            private static final int REQUEST_ENABLE_BT = 2;
            Button mScan, mPrint, mDisc;
            BluetoothAdapter mBluetoothAdapter;
            private UUID applicationUUID = UUID
                    .fromString("00001101-0000-1000-8000-00805F9B34FB");
            private ProgressDialog mBluetoothConnectProgressDialog;
            private BluetoothSocket mBluetoothSocket;
            BluetoothDevice mBluetoothDevice;

            @Override
            public void onCreate(Bundle mSavedInstanceState) {
                super.onCreate(mSavedInstanceState);
                requestWindowFeature(Window.FEATURE_NO_TITLE);
                getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                        WindowManager.LayoutParams.FLAG_FULLSCREEN);
                setContentView(R.layout.main);
                mScan = (Button) findViewById(R.id.Scan);
                mScan.setOnClickListener(new View.OnClickListener() {
                    public void onClick(View mView) {
                        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
                        if (mBluetoothAdapter == null) {
                            Toast.makeText(Main.this, "Message1", 2000).show();
                        } else {
                            if (!mBluetoothAdapter.isEnabled()) {
                                Intent enableBtIntent = new Intent(
                                        BluetoothAdapter.ACTION_REQUEST_ENABLE);
                                startActivityForResult(enableBtIntent,
                                        REQUEST_ENABLE_BT);
                            } else {
                                ListPairedDevices();
                                Intent connectIntent = new Intent(Main.this,
                                        DeviceListActivity.class);
                                startActivityForResult(connectIntent,
                                        REQUEST_CONNECT_DEVICE);
                            }
                        }
                    }
                });

                mPrint = (Button) findViewById(R.id.mPrint);
                mPrint.setOnClickListener(new View.OnClickListener() {
                    public void onClick(View mView) {
                        Thread t = new Thread() {
                            public void run() {
                                try {
                                    OutputStream os = mBluetoothSocket
                                            .getOutputStream();
                                    String BILL = "";

                                    BILL = "\nInvoice No: 00000000000000000 " + "    "
                                            + "04-08-2011\n";
                                    BILL = BILL
                                            + "-----------------------------------------";
                                    BILL = BILL + "\n\n";
                                    BILL = BILL + "Total Qty:" + "      " + "1.0\n";
                                    BILL = BILL + "Total Value:" + "     "
                                            + "80000.0\n";
                                    BILL = BILL
                                            + "-----------------------------------------\n";
                                    os.write(BILL.getBytes());
                                        //This is printer specific code you can comment ==== > Start

                                    // Setting height
                                    int gs = 29;
                                    os.write(intToByteArray(gs));
                                    int h = 104;
                                    os.write(intToByteArray(h));
                                    int n = 162;
                                    os.write(intToByteArray(n));

                                    // Setting Width
                                    int gs_width = 29;
                                    os.write(intToByteArray(gs_width));
                                    int w = 119;
                                    os.write(intToByteArray(w));
                                    int n_width = 2;
                                    os.write(intToByteArray(n_width));

                                    // Print BarCode
                                    int gs1 = 29;
                                    os.write(intToByteArray(gs1));
                                    int k = 107;
                                    os.write(intToByteArray(k));
                                    int m = 73;
                                    os.write(intToByteArray(m));

                                    String barCodeVal = "ASDFC028060000005";// "HELLO12345678912345012";
                                    System.out.println("Barcode Length : "
                                            + barCodeVal.length());
                                    int n1 = barCodeVal.length();
                                    os.write(intToByteArray(n1));

                                    for (int i = 0; i < barCodeVal.length(); i++) {
                                        os.write((barCodeVal.charAt(i) + "").getBytes());
                                    }
       //printer specific code you can comment ==== > End
                                } catch (Exception e) {
                                    Log.e("Main", "Exe ", e);
                                }
                            }
                        };
                        t.start();
                    }
                });

                mDisc = (Button) findViewById(R.id.dis);
                mDisc.setOnClickListener(new View.OnClickListener() {
                    public void onClick(View mView) {
                        if (mBluetoothAdapter != null)
                            mBluetoothAdapter.disable();
                    }
                });

            }// onCreate

            @Override
            protected void onDestroy() {
                // TODO Auto-generated method stub
                super.onDestroy();
                try {
                    if (mBluetoothSocket != null)
                        mBluetoothSocket.close();
                } catch (Exception e) {
                    Log.e("Tag", "Exe ", e);
                }
            }

            @Override
            public void onBackPressed() {
                try {
                    if (mBluetoothSocket != null)
                        mBluetoothSocket.close();
                } catch (Exception e) {
                    Log.e("Tag", "Exe ", e);
                }
                setResult(RESULT_CANCELED);
                finish();
            }

            public void onActivityResult(int mRequestCode, int mResultCode,
                    Intent mDataIntent) {
                super.onActivityResult(mRequestCode, mResultCode, mDataIntent);

                switch (mRequestCode) {
                case REQUEST_CONNECT_DEVICE:
                    if (mResultCode == Activity.RESULT_OK) {
                        Bundle mExtra = mDataIntent.getExtras();
                        String mDeviceAddress = mExtra.getString("DeviceAddress");
                        Log.v(TAG, "Coming incoming address " + mDeviceAddress);
                        mBluetoothDevice = mBluetoothAdapter
                                .getRemoteDevice(mDeviceAddress);
                        mBluetoothConnectProgressDialog = ProgressDialog.show(this,
                                "Connecting...", mBluetoothDevice.getName() + " : "
                                        + mBluetoothDevice.getAddress(), true, false);
                        Thread mBlutoothConnectThread = new Thread(this);
                        mBlutoothConnectThread.start();
                        // pairToDevice(mBluetoothDevice); This method is replaced by
                        // progress dialog with thread
                    }
                    break;

                case REQUEST_ENABLE_BT:
                    if (mResultCode == Activity.RESULT_OK) {
                        ListPairedDevices();
                        Intent connectIntent = new Intent(Main.this,
                                DeviceListActivity.class);
                        startActivityForResult(connectIntent, REQUEST_CONNECT_DEVICE);
                    } else {
                        Toast.makeText(Main.this, "Message", 2000).show();
                    }
                    break;
                }
            }

            private void ListPairedDevices() {
                Set<BluetoothDevice> mPairedDevices = mBluetoothAdapter
                        .getBondedDevices();
                if (mPairedDevices.size() > 0) {
                    for (BluetoothDevice mDevice : mPairedDevices) {
                        Log.v(TAG, "PairedDevices: " + mDevice.getName() + "  "
                                + mDevice.getAddress());
                    }
                }
            }

            public void run() {
                try {
                    mBluetoothSocket = mBluetoothDevice
                            .createRfcommSocketToServiceRecord(applicationUUID);
                    mBluetoothAdapter.cancelDiscovery();
                    mBluetoothSocket.connect();
                    mHandler.sendEmptyMessage(0);
                } catch (IOException eConnectException) {
                    Log.d(TAG, "CouldNotConnectToSocket", eConnectException);
                    closeSocket(mBluetoothSocket);
                    return;
                }
            }

            private void closeSocket(BluetoothSocket nOpenSocket) {
                try {
                    nOpenSocket.close();
                    Log.d(TAG, "SocketClosed");
                } catch (IOException ex) {
                    Log.d(TAG, "CouldNotCloseSocket");
                }
            }

            private Handler mHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    mBluetoothConnectProgressDialog.dismiss();
                    Toast.makeText(Main.this, "DeviceConnected", 5000).show();
                }
            };

            public static byte intToByteArray(int value) {
                byte[] b = ByteBuffer.allocate(4).putInt(value).array();

                for (int k = 0; k < b.length; k++) {
                    System.out.println("Selva  [" + k + "] = " + "0x"
                            + UnicodeFormatter.byteToHex(b[k]));
                }

                return b[3];
            }

            public byte[] sel(int val) {
                ByteBuffer buffer = ByteBuffer.allocate(2);
                buffer.putInt(val);
                buffer.flip();
                return buffer.array();
            }

        }






UnicodeFormatter.java





  import java.io.*;

    public class UnicodeFormatter {

        static public String byteToHex(byte b) {
                // Returns hex String representation of byte b
                char hexDigit[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                        'a', 'b', 'c', 'd', 'e', 'f' };
                char[] array = { hexDigit[(b >> 4) & 0x0f], hexDigit[b & 0x0f] };
                return new String(array);
        }

        static public String charToHex(char c) {
                // Returns hex String representation of char c
                byte hi = (byte) (c >>> 8);
                byte lo = (byte) (c & 0xff);
                return byteToHex(hi) + byteToHex(lo);
        }

    } // class







DeviceListActivity.java





 import java.util.Set; 
          import android.app.Activity; 
          import android.bluetooth.BluetoothAdapter; 
          import android.bluetooth.BluetoothDevice; 
          import android.content.Intent; 
          import android.os.Bundle; 
          import android.util.Log; 
          import android.view.View; 
          import android.view.Window; 
          import android.widget.AdapterView; 
          import android.widget.ArrayAdapter; 
          import android.widget.ListView; 
          import android.widget.TextView; 
          import android.widget.AdapterView.OnItemClickListener; 

    public class DeviceListActivity extends Activity 
    { 
    protected static final String TAG = "TAG"; 
    private BluetoothAdapter mBluetoothAdapter; 
    private ArrayAdapter<String> mPairedDevicesArrayAdapter; 

    @Override 
    protected void onCreate(Bundle mSavedInstanceState) 
    { 
        super.onCreate(mSavedInstanceState); 
        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); 
        setContentView(R.layout.device_list); 

        setResult(Activity.RESULT_CANCELED); 
        mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name); 

        ListView mPairedListView = (ListView) findViewById(R.id.paired_devices); 
        mPairedListView.setAdapter(mPairedDevicesArrayAdapter); 
        mPairedListView.setOnItemClickListener(mDeviceClickListener); 

        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); 
        Set<BluetoothDevice> mPairedDevices = mBluetoothAdapter.getBondedDevices(); 

        if (mPairedDevices.size() > 0) 
        { 
            findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE); 
            for (BluetoothDevice mDevice : mPairedDevices) 
            { 
                mPairedDevicesArrayAdapter.add(mDevice.getName() + "\n" + mDevice.getAddress()); 
            } 
        } 
        else 
        { 
            String mNoDevices = "None Paired";//getResources().getText(R.string.none_paired).toString(); 
            mPairedDevicesArrayAdapter.add(mNoDevices); 
        } 
    } 

    @Override 
    protected void onDestroy() 
    { 
        super.onDestroy(); 
        if (mBluetoothAdapter != null) 
        { 
            mBluetoothAdapter.cancelDiscovery(); 
        } 
    } 

    private OnItemClickListener mDeviceClickListener = new OnItemClickListener() 
    { 
        public void onItemClick(AdapterView<?> mAdapterView, View mView, int mPosition, long mLong) 
        { 
            mBluetoothAdapter.cancelDiscovery(); 
            String mDeviceInfo = ((TextView) mView).getText().toString(); 
            String mDeviceAddress = mDeviceInfo.substring(mDeviceInfo.length() - 17); 
            Log.v(TAG, "Device_Address " + mDeviceAddress); 

            Bundle mBundle = new Bundle(); 
            mBundle.putString("DeviceAddress", mDeviceAddress); 
            Intent mBackIntent = new Intent(); 
            mBackIntent.putExtras(mBundle); 
            setResult(Activity.RESULT_OK, mBackIntent); 
            finish(); 
        } 
    }; 

     } 






main.xml





<?xml version="1.0" encoding="utf-8"?>
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
        <Button android:text="Scan" 
        android:id="@+id/Scan"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"></Button>
        <Button android:text="Print"
        android:id="@+id/mPrint"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"></Button>
        <Button android:text="Dissable"
        android:id="@+id/dis"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"></Button>
        </LinearLayout>





device_name.xml





 <?xml version="1.0" encoding="utf-8"?> 
    <TextView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:textSize="18sp"
    android:padding="5dip" /> 





device_list.xml





    <?xml version="1.0" encoding="utf-8"?> 
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"> 
    <TextView android:id="@+id/title_paired_devices" 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" 
    android:text="My Text"
    android:visibility="gone" 
    android:background="#666" 
    android:textColor="#fff" 
    android:paddingLeft="5dip" /> 
    <ListView android:id="@+id/paired_devices" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:stackFromBottom="true" 
    android:layout_weight="1" /> 
    </LinearLayout>





Manifest






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




	


	
	






	
	

		
Edittext Text ChangeListener Kotlin
	


	

		

Action whenever the text is changed in the EditText View.





Application to implement a listener

TextWatcher object, for EditText to trigger an action on text change.





Create a new Project in Kotlin










Message can display outside of our application normal UI





1 Open Android Studio.
 2 Go to File => New => New Project. Write application name . Then, check Include Kotlin Support and click next button.
 3Select minimum SDK you need. However, we have selected 17 as minimum SDK. Then, click next button
 4 Then, select Empty Activity => click next => click finish.
 5 You will get a newly created project successfully if you have followed steps properly.





Use the below code to Implement a Edittext with Kotlin





MainActivity.kt





import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.text.Editable
import android.text.TextWatcher
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        editTextSample.addTextChangedListener(object : TextWatcher {

            override fun afterTextChanged(s: Editable) {}

            override fun beforeTextChanged(s: CharSequence, start: Int,
                                           count: Int, after: Int) {
            }

            override fun onTextChanged(s: CharSequence, start: Int,
                                       before: Int, count: Int) {
                tvSample.setText("Text is : "+s)
            }
        })
    }
}








main_activity.xml





<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="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">

    <LinearLayout
            android:layout_marginTop="20dp"
            android:orientation="vertical"
            android:padding="10sp"
            android:gravity="center_horizontal"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            android:layout_height="wrap_content" />

        <EditText
                android:id="@+id/editTextSample"
                android:textSize="20sp"
                android:layout_marginTop="50dp"
                android:hint="Enter Text ..."
                android:layout_width="match_parent"
                android:layout_height="wrap_content"/>



        <TextView
                android:id="@+id/tvSample"
                android:layout_marginTop="20dp"
                android:textColor="@color/colorPrimary"
                android:textStyle="bold"
                android:textSize="16dp"
                android:layout_width="wrap_content"
                  android:layout_height="wrap_content"/>

    </LinearLayout>

</android.support.constraint.ConstraintLayout>








	


	
	






	
	

		
Notifications in Kotlin Oreo (8+)
	


	

		

Create a new Project in Kotlin





Message can display outside of our application normal UI










1  Open Android Studio.
    2 Go to File => New => New Project. Write application name . Then, check Include Kotlin Support and click next button.
     3Select minimum SDK you need. However, we have selected 17 as minimum SDK. Then, click next button
  4   Then, select Empty Activity => click next => click finish.
  5   You will get a newly created project successfully if you have followed steps properly. 





added line in the build.gradle (Module: app) dependencies:





implementation 'com.android.support:appcompat-v7:26.1.0'





Use the below code to Implement a Notification with Kotlin





 MainActivity.k





import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.*
import kotlinx.android.synthetic.main.activity_main.*
import android.widget.RadioGroup
import android.widget.Toast
import android.app.NotificationManager
import android.support.v4.app.NotificationCompat
import android.os.Build
import android.app.NotificationChannel
import android.content.Context
import android.support.annotation.RequiresApi
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
   val button:Button=findViewById(R.id.button);
        button.setOnClickListener()

        {

            issueNotification()

        }
    }


    @RequiresApi(api = Build.VERSION_CODES.O)
    fun makeNotificationChannel(id: String, name: String, importance: Int) {
        val channel = NotificationChannel(id, name, importance)
        channel.setShowBadge(true) // set false to disable badges, Oreo exclusive

        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        notificationManager.createNotificationChannel(channel)
    }


    fun issueNotification() {

        // make the channel. The method has been discussed before.
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            makeNotificationChannel("CHANNEL_1", "Example channel", NotificationManager.IMPORTANCE_DEFAULT)
        }
        // the check ensures that the channel will only be made
        // if the device is running Android 8+

        val notification = NotificationCompat.Builder(this, "CHANNEL_1")
        // the second parameter is the channel id.
        // it should be the same as passed to the makeNotificationChannel() method

        notification
            .setSmallIcon(R.mipmap.ic_launcher) // can use any other icon
            .setContentTitle("Notification!")
            .setContentText("This is an Oreo notification!")
            .setNumber(3) // this shows a number in the notification dots

        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        notificationManager.notify(1, notification.build())
        // it is better to not use 0 as notification id, so used 1.
    }


}





activity_main.xml





<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/root_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
 <Button

            android:id="@+id/button"
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="15dp"
            android:text="click"
    />
</LinearLayout>








	


	
	






	
	

		
Android Radio Buttons Using Kotlin With Example
	


	

		

Radio buttons allow the user to select one option at a time. A RadioButton  as  two states, selected and unselected.   





          





Create a new Project in Kotlin 





  1. Open Android Studio.
  2. Go to File => New => New  Project. Write application name . Then, check Include Kotlin  Support and click next button.
  3. Select minimum SDK you need. However, we have selected 17 as minimum SDK. Then, click next button
  4. Then, select Empty Activity => click next => click finish.
  5. You will get a newly created project successfully if you have followed steps properly. 





Use the below code to Implement a Radio Buttons with Kotlin





MainActivity.kt










activity_main.xml





import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.*
import kotlinx.android.synthetic.main.activity_main.*
import android.widget.RadioGroup
import android.widget.Toast

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


//Radio button on click change

radio_group.setOnCheckedChangeListener(
    RadioGroup.OnCheckedChangeListener{
        group, checkedId ->

        val radio_langange: RadioButton = findViewById(checkedId)


        Toast.makeText(applicationContext," On Checked change :${radio_langange.text}",Toast.LENGTH_SHORT).show()


    }
)

        // Get radio group selected status and text using button click event
      button.setOnClickListener{
           // Get the checked radio button id from radio group
           var id: Int = radio_group.checkedRadioButtonId
          if (id!=-1){ // If any radio button checked from radio group
              // Get the instance of radio button using id
               val radio:RadioButton = findViewById(id)
            Toast.makeText(applicationContext,"On button click : ${radio.text}",
                 Toast.LENGTH_SHORT).show()
            }else{
                // If no radio button checked in this radio group
               Toast.makeText(applicationContext,"On button click : nothing selected",
                   Toast.LENGTH_SHORT).show()
          }
      }
   }

    // Get the selected radio button text using radio button on click listener
    fun radio_button_click(view: View){
      // Get the clicked radio button instance
      val radio: RadioButton = findViewById(radio_group.checkedRadioButtonId)
       Toast.makeText(applicationContext,"On click : ${radio.text}",
         Toast.LENGTH_SHORT).show()
    }
}





activity_main.xml





<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/root_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:padding="16dp"
>
    <RadioGroup
            android:layout_marginTop="30dp"
            android:id="@+id/radio_group"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#bccdd5"
            android:padding="15dp"
    >
        <TextView
                android:id="@+id/title"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Which is your favorite languages?"
                android:textStyle="bold"
                android:textSize="20sp"
        />
        <RadioButton
                android:id="@+id/tvenglish"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="English"
                android:onClick="radio_button_click"
        />
        <RadioButton
                android:id="@+id/tvspanish"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Spanish"
                android:onClick="radio_button_click"
        />
        <RadioButton
                android:id="@+id/tvfrench"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="French"
                android:onClick="radio_button_click"
        />
        <RadioButton
                android:id="@+id/tvmalayalam"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Malayalam"
                android:onClick="radio_button_click"
        />
    </RadioGroup>

    <Button

            android:id="@+id/button"
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="15dp"
            android:text="Get Selected Language"
    />
</LinearLayout>