main activity java file for alarm clock

package com.example.alarmclock;

import androidx.appcompat.app.AppCompatActivity;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {
    EditText e1;
    Button b1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        e1 = findViewById(R.id.e1);
        b1 = findViewById(R.id.b1);


        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startalert();
            }
        });
    }


    public void startalert() {
        int i = Integer.parseInt(e1.getText().toString());
        Intent in = new Intent(this, MyReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(),
                900000, in, 0);
        AlarmManager
                alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() +
                (i * 1000), pendingIntent);
        Toast.makeText(getApplicationContext(), "Alaram set in " + i + " Seconds", Toast.LENGTH_LONG).show();
    }
}