How to Set Alarm in Android Studio Programatically

 How to set alarm in android studio , here we see how to set alarm at selected time and play alarm selected time. First you have to add permission for alarm wake_lock.

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

 and now set layout.xml file

<RelativeLayout 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"
   >

    <TimePicker
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/alarmTimePicker"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />


    <ToggleButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Alarm On/Off"
        android:id="@+id/alarmToggle"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/alarmTimePicker"
        android:onClick="onToggleClicked" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text=""
        android:id="@+id/alarmText"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:layout_below="@+id/alarmToggle" />

</RelativeLayout>
now in AlarmActivity.java this is the main activity to do code for select time and set alarm on that 
selected time.

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import android.widget.TimePicker;
import android.widget.ToggleButton;

import java.util.Calendar;


public class AlarmActivity extends Activity {

    AlarmManager alarmManager;
    private PendingIntent pendingIntent;
    private TimePicker alarmTimePicker;
    private static AlarmActivity inst;
    private TextView alarmTextView;

    public static AlarmActivity instance() {
        return inst;
    }

    @Override
    public void onStart() {
        super.onStart();
        inst = this;
    }

    ToggleButton  alarmToggle;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        alarmTimePicker = (TimePicker) findViewById(R.id.alarmTimePicker);
        alarmTextView = (TextView) findViewById(R.id.alarmText);
        alarmToggle = (ToggleButton) findViewById(R.id.alarmToggle);
        alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);


        alarmToggle.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (((ToggleButton) view).isChecked()) {
                    Log.d("MyActivity", "Alarm On");
                    Calendar calendar = Calendar.getInstance();
                    calendar.set(Calendar.HOUR_OF_DAY, alarmTimePicker.getCurrentHour());
                    calendar.set(Calendar.MINUTE, alarmTimePicker.getCurrentMinute());
                    Intent myIntent = new Intent(getApplicationContext(), AlarmReceiver.class);
                    pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 1, myIntent, PendingIntent.FLAG_UPDATE_CURRENT);
                    alarmManager.set(AlarmManager.RTC, calendar.getTimeInMillis(), pendingIntent);
                } else {
                    //alarmManager.cancel(pendingIntent);

//            AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
          /*  Intent myIntent = new Intent(getApplicationContext(), AlarmReceiver.class);
            PendingIntent pendingIntent = PendingIntent.getBroadcast(
                    getApplicationContext(), 1, myIntent,
                    PendingIntent.FLAG_UPDATE_CURRENT);*/

                    alarmManager.cancel(pendingIntent);

                    AlarmReceiver.ringtone.stop();
                    setAlarmText("");
                    Log.d("MyActivity", "Alarm Off");
                }

            }
        });
    }

    public void setAlarmText(String alarmText) {
        alarmTextView.setText(alarmText);
    }
}
now create AlarmReceiver.java class 

import android.app.IntentService;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.util.Log;

import androidx.core.app.NotificationCompat;

public class AlarmService extends IntentService {
    private NotificationManager alarmNotificationManager;

    public AlarmService() {

        super("AlarmService");
    }

    @Override
    public void onHandleIntent(Intent intent) {
        sendNotification("Wake Up! Wake Up!");
    }

    private void sendNotification(String msg) {
        Log.d("AlarmService", "Preparing to send notification.. " + msg);
        alarmNotificationManager = (NotificationManager) this
                .getSystemService(Context.NOTIFICATION_SERVICE);

        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, AlarmActivity.class), 0);

        NotificationCompat.Builder alamNotificationBuilder = new NotificationCompat.Builder(
                this).setContentTitle("Alarm").setSmallIcon(R.mipmap.ic_launcher)
                .setStyle(new NotificationCompat.BigTextStyle().bigText(msg))
                .setContentText(msg);


        alamNotificationBuilder.setContentIntent(contentIntent);
        alarmNotificationManager.notify(1, alamNotificationBuilder.build());
        Log.d("AlarmService", "Notification sent.");
    }
}
now create receiver name AlarmReceiver.java 

import android.app.Activity;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.media.Ringtone;
import android.media.RingtoneManager;
import android.net.Uri;

public class AlarmReceiver extends BroadcastReceiver {

    public static Ringtone ringtone;

    @Override
    public void onReceive(final Context context, Intent intent) {
        //this code is display UI with message
        AlarmActivity inst = AlarmActivity.instance();
        inst.setAlarmText("Alarm! Wake up! Wake up!");

        //this code will sound the alarm tone
                
        Uri alarmUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
        if (alarmUri == null) {
            alarmUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        }
        ringtone = RingtoneManager.getRingtone(context, alarmUri);
        ringtone.play();

        //this code will send a notification message
        ComponentName comp = new ComponentName(context.getPackageName(),
                AlarmService.class.getName());
        peekService(context,(intent.setComponent(comp)));
        setResultCode(Activity.RESULT_OK);
    }
}

This is the code to set Alarm at selected time in android studio.
Below is the code for Set Alarm in android studio programatically.