Code: Started Services

package org.meicode.startedservices;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

        Intent intent = new Intent(this, SecondExampleService.class);
        intent.putExtra("number", 5);
        startService(intent);
        startService(intent);

        stopService(intent);
    }
}

package org.meicode.startedservices;

import android.app.IntentService;
import android.content.Intent;
import android.os.SystemClock;
import android.util.Log;

import androidx.annotation.Nullable;

public class ExampleService extends IntentService {
    private static final String TAG = "ExampleService";

    public ExampleService() {
        super("DownloadThread");
    }

    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
        try{
            int number = intent.getIntExtra("number", -1);
            if (number != -1) {
                for (int i=0; i<number; i++) {
                    Log.d(TAG, "onHandleIntent: number: " + i);
                    SystemClock.sleep(1000);
                }
            }
        }catch (NullPointerException e) {
            e.printStackTrace();
        }
    }
}

package org.meicode.startedservices;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.SystemClock;
import android.util.Log;

import androidx.annotation.Nullable;

public class SecondExampleService extends Service {
    private static final String TAG = "SecondExampleService";

    private int serviceId = -1;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        this.serviceId = startId;

        try {
            final int number = intent.getIntExtra("number", -1);
            if (number != -1) {
                Thread thread = new Thread(new Runnable() {
                    @Override
                    public void run() {
                        for (int i=0; i<number; i++) {
                            Log.d(TAG, "onHandleIntent: number: " + i);
                            SystemClock.sleep(1000);
                        }
                    }
                });

                thread.start();
            }
        }catch (NullPointerException e) {
            e.printStackTrace();
        }

        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        stopSelf(serviceId);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.meicode.startedservices">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service android:name=".ExampleService"
            android:exported="false"
            android:description="@string/service_desc"/>
        <service android:name=".SecondExampleService"
            android:exported="false"
            android:description="@string/service_desc"/>
    </application>

</manifest>

<resources>
    <string name="app_name">Started Services</string>

    <string name="service_desc">This service is for downloading</string>
</resources>