//Getting intent and PendingIntent instance
Intent intent=new Intent(getApplicationContext(),MainActivity.class);
PendingIntent pi=PendingIntent.getActivity(getApplicationContext(), 0, intent,0);

//Get the SmsManager instance and call the sendTextMessage method to send message
SmsManager sms=SmsManager.getDefault();
sms.sendTextMessage("8802177690", null, "hello javatpoint", pi,null);

package com.example.sendsms;

import android.os.Bundle;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Intent;
import android.telephony.SmsManager;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

EditText mobileno,message;
Button sendsms;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        mobileno=(EditText)findViewById(R.id.editText1);
        message=(EditText)findViewById(R.id.editText2);
        sendsms=(Button)findViewById(R.id.button1);
        
//Performing action on button click
        sendsms.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
String no=mobileno.getText().toString();
String msg=message.getText().toString();

//Getting intent and PendingIntent instance
Intent intent=new Intent(getApplicationContext(),MainActivity.class);
PendingIntent pi=PendingIntent.getActivity(getApplicationContext(), 0, intent,0);

//Get the SmsManager instance and call the sendTextMessage method to send message
SmsManager sms=SmsManager.getDefault();
sms.sendTextMessage(no, null, msg, pi,null);

Toast.makeText(getApplicationContext(), "Message Sent successfully!",
Toast.LENGTH_LONG).show();
}
});
    }

    @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;
    }
    
}