package com.example.uzduotisdu;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;


import static android.app.Service.START_STICKY;

public class SimpleService extends Service {
    @Override
    public IBinder onBind(Intent intent){
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        NotificationHelper notificationHelper = new NotificationHelper(getBaseContext());
        notificationHelper.createNotification("Just a title", "And some meaningful text here");
        return START_STICKY;
    }


    @Override
    public void onDestroy(){
        super.onDestroy();
        Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();
    }

}



ServiceTestActivity:



package com.example.uzduotisdu;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.graphics.Color;
import android.provider.Settings;

import android.app.ActivityManager;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;



class NotificationHelper {
    private Context mContext;
    private NotificationManager mNotificationManager;
    private NotificationCompat.Builder mBuilder;
    private static final String NOTIFICATION_CHANNEL_ID = "10001";

    NotificationHelper(Context context) {
        mContext = context;
    }

    void createNotification(String title, String message)
    {
        Intent resultIntent = new Intent(mContext, MainActivity.class);
        resultIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        PendingIntent resultPendingIntent = PendingIntent.getActivity(mContext,
                0 /* Request code */, resultIntent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        mBuilder = new NotificationCompat.Builder(mContext, NOTIFICATION_CHANNEL_ID);
        mBuilder.setSmallIcon(R.mipmap.ic_launcher);
        mBuilder.setContentTitle(title)
                .setContentText(message)
                .setAutoCancel(false)
                .setSound(Settings.System.DEFAULT_NOTIFICATION_URI)
                .setContentIntent(resultPendingIntent);
        mNotificationManager = (NotificationManager) mContext.getSystemService(Context.NOTIFICATION_SERVICE);

        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O)
        {
            int importance = NotificationManager.IMPORTANCE_HIGH;
            NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID,
                    "NOTIFICATION_CHANNEL_NAME", importance);
            notificationChannel.enableLights(true);
            notificationChannel.setLightColor(Color.RED);
            notificationChannel.enableVibration(true);
            notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
            assert mNotificationManager != null;
            mBuilder.setChannelId(NOTIFICATION_CHANNEL_ID);
            mNotificationManager.createNotificationChannel(notificationChannel);
        }

        assert mNotificationManager != null;
        mNotificationManager.notify(0, mBuilder.build());
    }

}

public class ServiceTestACtivity extends AppCompatActivity implements View.OnClickListener {



    private void setup_on_clicks(){
        findViewById(R.id.start_btn).setOnClickListener(this);
        findViewById(R.id.stop_btn).setOnClickListener(this);
    }

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



    private void startService() {
        if(!isMyServiceRunning(SimpleService.class)) {
            startService(new Intent(getBaseContext(), SimpleService.class));
        } else {
            Toast.makeText(this, "Service already running", Toast.LENGTH_LONG).show();
        }
    }
    private void stopService() {
        stopService(new Intent(getBaseContext(), SimpleService.class));
    }

    private boolean isMyServiceRunning(Class<?> serviceClass) {
        ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
        for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
            if (serviceClass.getName().equals(service.service.getClassName())){
                return true;
            }
        }
        return false;
    }
    public void onClick(View view){
        switch (view.getId()){
            case (R.id.start_btn):
                startService();
                break;
            case (R.id.stop_btn):
                stopService();
                break;
        }
    }
}