Blocking any other application via Service

Talk, I'm creating a business application and I need to block any other application that the user tries to open. I'm creating a service for this, but it's not working.

When run, it does not see the other applications when opened by the user.

I read some other posts here, but I could not figure it out.

Below is my service.

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity);

        startService(new Intent(this, clsServico.class));
    }

My class:

import android.app.ActivityManager;
import android.app.Service;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.Build;
import android.os.IBinder;
import android.preference.PreferenceManager;
import android.util.Log;

import java.util.Collections;
import java.util.List;
import java.util.concurrent.TimeUnit;


public class clsServico extends Service {

    private static final long INTERVAL = TimeUnit.SECONDS.toMillis(2); // em segundos
    private static final String TAG = clsServico.class.getSimpleName();
    private static final String APS_BG = "APS_BG";

    private Thread t = null;
    private Context ctx = null;
    private boolean running = false;

    @Override
    public void onDestroy() {
        running =false;
        super.onDestroy();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        running = true;
        ctx = this;

        // checa periodicamente se tem algum outro app na tela
        t = new Thread(new Runnable() {
            @Override
            public void run() {
                do {
                    //checkAPS();

                    try {
                        if(Build.VERSION.SDK_INT >= 21)
                            listTasks();
                        else
                            listTasks_SDK21();

                    } catch (PackageManager.NameNotFoundException e) {

                    }

                    try {
                        Thread.sleep(INTERVAL);
                    } catch (InterruptedException e) {
                    }
                }while(running);
                stopSelf();
            }
        });

        t.start();
        return Service.START_NOT_STICKY;
    }

    public void listTasks() throws PackageManager.NameNotFoundException {
        if(Build.VERSION.SDK_INT >= 21) {
            ActivityManager mgr = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
            List<ActivityManager.AppTask> tasks = mgr.getAppTasks();
            String packagename;
            String label;
            for (ActivityManager.AppTask task : tasks) {
                packagename = task.getTaskInfo().baseIntent.getComponent().getPackageName();
                label = getPackageManager().getApplicationLabel(getPackageManager().getApplicationInfo(packagename, PackageManager.GET_META_DATA)).toString();
                //Log.i(TAG, packagename + ":" + label);
            }
        }
    }

    public void listTasks_SDK21() throws PackageManager.NameNotFoundException {
        ActivityManager mgr = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RecentTaskInfo> tasks = mgr.getRecentTasks(20, 0);
        String packagename;
        String label;
        for(ActivityManager.RecentTaskInfo task: tasks){
            packagename = task.baseIntent.getComponent().getPackageName();
            label = getPackageManager().getApplicationLabel(getPackageManager().getApplicationInfo(packagename, PackageManager.GET_META_DATA)).toString();
            Log.i(TAG,packagename + ":" + label);
        }
    }

    private void checkAPS() {
        /*
        if(apenasAPSAtivado(ctx)) {
            if(isInBackground()) {
                restoreApp(); // tras p frente
            }
        }
        */

        PackageManager packageManager = getPackageManager();
        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
        mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

        ActivityManager mActivityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);


        List<ResolveInfo> appList = packageManager.queryIntentActivities(mainIntent, 0);
        Collections.sort(appList, new ResolveInfo.DisplayNameComparator(packageManager));
        List<PackageInfo> packs = packageManager.getInstalledPackages(0);
        for(int i=0; i < packs.size(); i++) {
            PackageInfo p = packs.get(i);
            ApplicationInfo a = p.applicationInfo;
            // skip system apps if they shall not be included
            if((a.flags & ApplicationInfo.FLAG_SYSTEM) == 1) {
                continue;
            }
            //Log.i("packageName","" + p.packageName);
        }

        List<ActivityManager.RunningTaskInfo> RunningTask = mActivityManager.getRunningTasks(1);
        ActivityManager.RunningTaskInfo run = RunningTask.get(0);
        Log.i("topActivity", run.topActivity.getClassName());




        Intent ints = new Intent(Intent.ACTION_MAIN, null);
        ints.addCategory(Intent.CATEGORY_LAUNCHER);

        List<ResolveInfo> intentlist = packageManager.queryIntentActivities(ints, PackageManager.PERMISSION_GRANTED);

        List<ActivityManager.RunningTaskInfo> processes = mActivityManager.getRunningTasks(Integer.MAX_VALUE);

        String pName = "";

        if (processes != null)
        {
            for (int i = 0; i < processes.size(); i++) {
                String packageName = processes.get(i).topActivity.getPackageName();
                ActivityManager.RunningTaskInfo temp = processes.get(i);
                try
                {
                    pName = (String) packageManager.getApplicationLabel(packageManager.getApplicationInfo(packageName, PackageManager.GET_META_DATA));
                }
                catch (PackageManager.NameNotFoundException e) {
                    e.printStackTrace();
                }

                //Log.i("RunningTaskInfo",pName + " : " + temp.id);
                /*
                if (savedapp.equals(pName)) {
                    // finish(pm.);
                    int code = intentlist.get(i).activityInfo.hashCode();
                    finishActivity(code);

                    mActivityManager.killBackgroundProcesses(packageName);
                    mActivityManager.restartPackage(packageName);
                    android.os.Process.killProcess(temp.id);
                    finishActivity(temp.id);
                }
                */

            }

        }


        List<ActivityManager.RunningTaskInfo> rt = mActivityManager.getRunningTasks(1000);
        for(int i = 0; i < rt.size(); i++){
            ActivityManager.RunningTaskInfo ar = rt.get(i);
            String activityOnTop=ar.topActivity.getClassName();
            //Log.i("rt", activityOnTop);
        }
        //ActivityManager.RunningTaskInfo ar = rt.get(0);
        //String activityOnTop=ar.topActivity.getClassName();
        //Log.i("activityOnTop", activityOnTop);


        //ActivityManager am = (ActivityManager)ctx.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> pids = mActivityManager.getRunningAppProcesses();
        for(int i = 0; i < pids.size(); i++)
        {
            ActivityManager.RunningAppProcessInfo p = pids.get(i);
            if(!p.processName.equalsIgnoreCase("nog.aps3")){
                android.os.Process.killProcess(p.pid);
                try {
                    android.os.Process.killProcess(p.pid);
                    android.os.Process.sendSignal(p.pid, android.os.Process.SIGNAL_KILL);
                    mActivityManager.killBackgroundProcesses(p.processName);
                } catch (Exception e) {
                    e.printStackTrace();
                    //Log.i("try", e.toString());
                }
            }

            //Log.i("info.processName", p.processName);
            //isInBackground();
        }

    }

    private boolean isInBackground() {
        ActivityManager am = (ActivityManager) ctx.getSystemService(Context.ACTIVITY_SERVICE);

        List<ActivityManager.RunningTaskInfo> taskInfo = am.getRunningTasks(1);
        ComponentName componentInfo = taskInfo.get(0).topActivity;
        //Log.i("getPackageName", ctx.getApplicationContext().getPackageName() +" =? "+ componentInfo.getPackageName());

        return (!ctx.getApplicationContext().getPackageName().equals(componentInfo.getPackageName()));
    }

    private void restoreApp() {
        //restore other class
    }

    public boolean apenasAPSAtivado(final Context context) {
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
        return sp.getBoolean(APS_BG, false);
    }

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

Can anyone help me with this, pls?