How to send a SMS using SMSmanager in Dual SIM mobile in Android ?

•     Add the following code to res/layout/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:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="4dp"
   tools:context=".MainActivity">
   <EditText
      android:hint="Enter mobile number"
      android:id="@+id/editTextNum"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"/>
   <EditText
      android:hint="Enter your message"
      android:id="@+id/editTextMsg"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"/>
   <Button
      android:id="@+id/btnSendMsg"
      android:onClick="SendSMS"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Send Message"/>
</LinearLayout>

•     Add the following code to src/MainActivity.java

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.telephony.SmsManager;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
   Button btnSend;
   EditText editTextNum, editTextMsg;
   private static final int PERMISSION_REQUEST = 101;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      editTextNum = findViewById(R.id.editTextNum);
      editTextMsg = findViewById(R.id.editTextMsg);
      btnSend = findViewById(R.id.btnSendMsg);
   }
   public void SendSMS(View view) {
      int permissionCheck = ContextCompat.checkSelfPermission(this, Manifest.permission.SEND_SMS);
      if (permissionCheck == PackageManager.PERMISSION_GRANTED){
         MyMessage();
      } else {
         ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.SEND_SMS},
PERMISSION_REQUEST);
      }
   }
   private void MyMessage() {
      String myNumber = editTextNum.getText().toString().trim();
      String myMsg = editTextMsg.getText().toString().trim();
      if (myNumber.equals("") || myMsg.equals("")){
         Toast.makeText(this, "Field cannot be empty", Toast.LENGTH_SHORT).show();
      } else {
         if (TextUtils.isDigitsOnly(myNumber)){
            SmsManager smsManager = SmsManager.getDefault();
            smsManager.sendTextMessage(myNumber, null, myMsg, null, null);
            Toast.makeText(this, "Message Sent", Toast.LENGTH_SHORT).show();
         } else {
            Toast.makeText(this, "Please enter the correct number", Toast.LENGTH_SHORT).show();
         }
      }
   }
   @Override
   public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
      super.onRequestPermissionsResult(requestCode, permissions, grantResults);
      if (requestCode == PERMISSION_REQUEST) {
         if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            MyMessage();
         } else {
            Toast.makeText(this, "You don't have required permission to send a message", Toast.LENGTH_SHORT).show();
         }
      }
   }
}

•     Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.com.sample">
   <uses-permission android:name="android.permission.SEND_SMS"/>
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

OutPut