Open/close app listener, using foreground and background callbacks!

AndroidManifest.xml

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

    <application
        android:name=".CustomApp"
        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>
    </application>

</manifest>

AppLifecycleHandler.java

package com.example.deyanmarinov.customrecyclerviewscroll;

import android.app.Activity;
import android.app.Application;
import android.content.ComponentCallbacks2;
import android.content.res.Configuration;
import android.os.Bundle;

public class AppLifecycleHandler implements Application.ActivityLifecycleCallbacks, ComponentCallbacks2 {

    private boolean appInForeground = false;
    private LifeCycleDelegate lifeCycleDelegate;

    public AppLifecycleHandler(LifeCycleDelegate lifeCycleDelegate) {
        this.lifeCycleDelegate = lifeCycleDelegate;
    }

    @Override
    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {

    }

    @Override
    public void onActivityStarted(Activity activity) {

    }

    @Override
    public void onActivityResumed(Activity activity) {
        if (!appInForeground) {
            appInForeground = true;
            this.lifeCycleDelegate.onAppForegrounded();
        }
    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {

    }

    @Override
    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

    }

    @Override
    public void onActivityDestroyed(Activity activity) {

    }

    @Override
    public void onTrimMemory(int level) {
        if (level == ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {
            appInForeground = false;
            lifeCycleDelegate.onAppBackgrounded();
        }
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {

    }

    @Override
    public void onLowMemory() {

    }
}

interface LifeCycleDelegate {
    void onAppBackgrounded();

    void onAppForegrounded();
}

CustomApp.java

package com.example.deyanmarinov.customrecyclerviewscroll;

import android.app.Application;
import android.util.Log;

public class CustomApp extends Application implements LifeCycleDelegate {

    @Override
    public void onCreate() {
        super.onCreate();
        AppLifecycleHandler lifecycleHandler = new AppLifecycleHandler(this);
        registerLifecycleHandler(lifecycleHandler);
    }

    @Override
    public void onAppBackgrounded() {
        Log.d("Awww", "App in background");
    }

    @Override
    public void onAppForegrounded() {
        Log.d("Yeeey", "App in foreground");
    }

    private void registerLifecycleHandler(AppLifecycleHandler lifeCycleHandler) {
        registerActivityLifecycleCallbacks(lifeCycleHandler);
        registerComponentCallbacks(lifeCycleHandler);
    }
}