我创建了一个在指定时间发出警报的应用程序。 但我也想向它发送带有预定义文本的通知。

这当前包含在Mainactivity.java中：

package com.example.reminder;

import androidx.appcompat.app.AppCompatactivity;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.TimePicker;
import android.widget.Toast;
import java.util.Calendar;

public class Mainactivity extends AppCompatactivity {

    TimePicker timePicker;

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

        timePicker=(TimePicker) findViewById(R.id.timePicker);
        timePicker.setIs24HourView(true);

        findViewById(R.id.buttonSetalarm).setOnClicklistener(new View.OnClicklistener() {
            @Override
            public void onClick(View view) {

                Calendar calendar = Calendar.getInstance();

                if(Build.VERSION.SDK_INT > 23) {
                calendar.set(
                        calendar.get(Calendar.YEAR),calendar.get(calendar.MONTH),calendar.get(calendar.DAY_OF_MONTH),timePicker.getHour(),timePicker.getMinute(),0
                );
            }else {
                    calendar.set(
                            calendar.get(Calendar.YEAR),timePicker.getcurrentHour(),timePicker.getcurrentMinute(),0
                    );
                }

                setalarm(calendar.getTimeInmillis());

            }
        });
    }

    private void setalarm(long timeInmillis) {
        AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);

        Intent intent  = new Intent(this,MyAlarm.class);

        PendingIntent pendingIntent= PendingIntent.getBroadcast(this,intent,0);

        alarmManager.setRepeating(AlarmManager.RTC,timeInmillis,AlarmManager.INTERVAL_DAY,pendingIntent);

        Toast.makeText(this,"Emlekezteto beallitva",Toast.LENGTH_SHORT).show();
    }

我该如何编写以发送带有预定义文本的通知并使用声音？

当前，我在一个单独的类（MyAlarm）中编写了使用系统铃声的信息。 MyAlarm.java：

package com.example.reminder;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.media.MediaPlayer;
import android.provider.Settings;

public class MyAlarm extends BroadcastReceiver {
    @Override
    public void onReceive(Context context,Intent intent) {
        MediaPlayer mediaPlayer = MediaPlayer.create(context,Settings.System.DEFAULT_RINGTONE_URI);
                mediaPlayer.start();
    }
}

有人可以帮我吗？

谢谢。