send sms android studio code

JAVA (MainActivity.java)

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.telephony.SmsManager;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.Manifest;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;

import com.tutorial.personal.androidstudiopro.R;

public class SendSMSactivity extends AppCompatActivity {
    private static final int MY_PERMISSIONS_REQUEST_SEND_SMS =0 ;
    Button send;
    EditText mobilenumber;
    EditText txtMessage;
    String phoneNo;
    String message;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_send_smsactivity);
        send = (Button) findViewById(R.id.btnSendSMS);
        mobilenumber = (EditText) findViewById(R.id.editText);
        txtMessage = (EditText) findViewById(R.id.editText2);

        send.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                sendSMSMessage();
            }
        });
    }

    protected void sendSMSMessage() {
        phoneNo = mobilenumber.getText().toString();
        message = txtMessage.getText().toString();

        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.SEND_SMS)
                != PackageManager.PERMISSION_GRANTED) {
            if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                    Manifest.permission.SEND_SMS)) {
            } else {
                ActivityCompat.requestPermissions(this,
                        new String[]{Manifest.permission.SEND_SMS},
                        MY_PERMISSIONS_REQUEST_SEND_SMS);
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,String permissions[], int[] grantResults) {
        switch (requestCode) {
            case MY_PERMISSIONS_REQUEST_SEND_SMS: {
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    SmsManager smsManager = SmsManager.getDefault();
                    smsManager.sendTextMessage(phoneNo, null, message, null, null);
                    Toast.makeText(getApplicationContext(), "SMS sent.",
                            Toast.LENGTH_LONG).show();
                } else {
                    Toast.makeText(getApplicationContext(),
                            "SMS faild, please try again.", Toast.LENGTH_LONG).show();
                    return;
                }
            }
        }

    }
}

XML (activity_main.xml)

<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
>

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:hint="Enter Phone Number"
        android:phoneNumber="true"
        app:layout_constraintBottom_toTopOf="@+id/editText2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="match_parent"
        android:layout_height="212dp"
        android:layout_below="@+id/editText"
        android:layout_alignStart="@+id/editText"
        android:layout_alignLeft="@+id/editText"
        android:hint="Enter SMS"
        app:layout_constraintBottom_toTopOf="@+id/btnSendSMS"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText" />

    <Button
        android:id="@+id/btnSendSMS"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editText2"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="Send Sms"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText2" />

</android.support.constraint.ConstraintLayout>