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How to stop opening default apps in android?

I am trying to make an android app for users in which user can activate Child protection. for example, User opens my app, he can view all the apps he has
(including default ones). Now if the user blocks default message or calls app then everything should be same, just these selected app must not open, even after anyone tap on these applications multiple time. It should look like nothing happening. I don't want to have a privacy PIN code or pattern on that app. I just want to stop the children by opening any app of mobile selected by the user through my application. Is this possible? if yes then any idea about how can i achieve this thing?

This problem is very similar to the one answered here, that will be my source for this answer. I can't try this code, but I hope it can give you a rough idea to make your first try and see yourself if it work or not.
The idea
The basic idea is to create a Background Service that continuously checks if there are open apps. If those apps are on the list the user locked, the show a lock screen. I don't know if it is possible to close an opened app¹ (I hope it's not!), but for your parental control functionality, a lock screen should have the same effect.
Select the apps to lock.
To retrieve from the system all apps that are installed
PackageManager packageManager = getPackageManager();
Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
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;
/* Uncomment this to exclude system apps
if ((a.flags & ApplicationInfo.FLAG_SYSTEM) == 1) {
continue;
} */
appList.add(p.packageName);
}
Now appList is a List<ResolveInfo>, and you can show to the user a ListView to let her choose the apps to be locked. Save these somewhere (SharedPreferences is an idea).
The service
What the service has to do is to:
Check the currently opened app:
ActivityManager mActivityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> RunningTask = mActivityManager.getRunningTasks(1);
ActivityManager.RunningTaskInfo ar = RunningTask.get(0);
activityOnTop = ar.topActivity.getClassName();
Check if activityOnTop is in the locked-apps list.
for(String appName : appList) {
if(appName.equals(activityOnTop)) {
// This app is locked!
LockApp(); // Defined later
break;
}
}
If so, start an Intent to your LockScreen activity (that won't allow any action)
private void LockApp() {
Intent lockIntent = new Intent(mContext, LockScreen.class);
lockIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
mContext.startActivity(lockIntent);
}
I give a lot of things for granted: you have to start a Service somewhere, you have to build a couple of activities, and this process does not avoid the problem of a smart kid that closes the process in background ... But I think this can work as a starting point.
¹ It apparently is possible. Give a look to this answer, an idea is to substitute the code in LockApp() with something like that.
This doesn't change that I think a Lock Screen is more elegant.

How some apps still can get current apps processes and kill them?

Background
In the past, I've found the next method of killing an app's background processes, given its package name:
public static boolean killApp(final Context context, final String packageName) {
final ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
final List<ActivityManager.RunningAppProcessInfo> pids = am.getRunningAppProcesses();
for (int i = 0; i < pids.size(); i++) {
final ActivityManager.RunningAppProcessInfo info = pids.get(i);
if (info.processName.equals(packageName)) {
android.os.Process.killProcess(info.pid);
if (new File("/system/bin/kill").exists()) {
InputStream inputStream = null;
try {
inputStream = Runtime.getRuntime().exec("kill -9 " + info.pid).getInputStream();
final byte[] buffer = new byte[100];
inputStream.read(buffer);
} catch (final IOException e) {
}
StreamsUtil.closeStream(inputStream);
}
am.killBackgroundProcesses(packageName);
return true;
}
}
am.killBackgroundProcesses(packageName);
return false;
}
The problem
Ever since a specific Android version (5.1), the function to get the list of running processes only returns the current app's processes, so it's quite useless to use it.
What I've found
Most apps on the Play Store indeed fail to show a list of processes, and instead, show just the current app's process or a list of services at most.
It seems that some apps still manage to show background apps processes and even be able to kill them. As an example, I've found AVG's app that's capable of doing so, here .
Before they can do it, they tell the user to enable the usage stats settings for the app, which I remember of using for checking general information of apps launch time.
Another app that succeeded killing background processes, yet without any user confirmation , is "fast task killer". It also shows a toast of all processes being killed. I could be wrong, but it seems that it's always the same number of tasks.
I also think there is a relatively easy way to get the list of processes using the "ps" function, but only if the device is rooted (otherwise it will return just the current app's processes).
There was a temporary solution with a library, found here (published here), but this doesn't seem to work on Android 7.1.2 , and most probably on previous versions.
The question
How do apps get the list of apps that have background processes, and how do they kill them?
Is it possible to do so without using the UsageStatsManager class ?

Listener for Phone Events and Voice command

My app uses a microphone(AudioRecord) in a background mode,How to make the listener for phone events and voice commands (like google voice). It is necessary for me to release a microphone(AudioRecord) for use.
I found a solution to phone events: http://www.botskool.com/geeks/how-listen-phone-events-android.
to use: TelephonyManager , PhoneStateListener.
But not to voice commands. Help pls.

There is no specific way you can do this (unfortunately) and it will only be the application that attempts to use the mic resource that will get an error.
What you can do is monitor what the user is doing in the background and react accordingly. Here is the code to check if Google Now has become the foreground application:
public static boolean googleNowForeground(final Context ctx) {
final ActivityManager activityManager = (ActivityManager) ctx.getSystemService(Context.ACTIVITY_SERVICE);
if (activityManager.getRunningTasks(1).get(0) != null) {
final PackageManager pm = ctx.getPackageManager();
try {
final PackageInfo foregroundAppPackageInfo = pm.getPackageInfo(
activityManager.getRunningTasks(1).get(0).topActivity.getPackageName(), 0);
if (foregroundAppPackageInfo != null) {
if (foregroundAppPackageInfo.packageName.matches(Constants.GOOGLE_NOW_PACKAGE_NAME)) {
return true;
}
}
} catch (NameNotFoundException e) {
e.printStackTrace();
}
}
return false;
}
This is the least 'expensive' way I've found to perform such actions, but the method above is not guaranteed to be called in future OS versions, not to mention having to hard-code the package names you are concerned with....
The 'expense' of monitoring for foreground applications that you know will conflict with your application may be somewhat minimal in comparison to permanently recording audio, but you should code your implementation wisely to minimise the monitor within certain device condition parameters.
I've investigated other methods to monitor intent broadcasts that are associated with mic resources, but they've been less successful than the above.
Requesting that the user create an 'exclude list' for the conflicting applications will allow you to dynamically monitor if they become the foreground application and react accordingly.
Hope that helps....

How to filter some of the application apps?

I need to display a screen with all the installed applications. I can do this already, but I need to filter some of the system applications. I am doing like this:
if((appInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 1)
This works, but the problem is that it hides apps like System, Video Player, and Sound Recorder. However, I need these apps to show up, too. The question is, how to do this?

You'll have to filter them manually via their process-name, e.g.:
if(appInfo.packageName().equals("com.android.soundrecorder"))
Please post more of your code if this doesn't work!

If an Application is a non-system application it must have a launch Intent by which it can be launched. If the launch intent is null then its a system App.
Example of System Apps: "com.android.browser.provider", "com.google.android.voicesearch".
For the above apps you will get NULL when you query for launch Intent.
PackageManager pm = getPackageManager();
List<ApplicationInfo> packages = pm.getInstalledApplications(PackageManager.GET_META_DATA);
for(ApplicationInfo packageInfo:packages){
if( pm.getLaunchIntentForPackage(packageInfo.packageName) != null ){
String currAppName = pm.getApplicationLabel(packageInfo).toString();
//This app is a non-system app
}
else{
//System App
}
}

Is there a way to get Process Ids of other 3rd party applications in Android...?

I have a requirement in my project where in i have to kill process of 3rd party application.
As i know Android can have multiple application running at a time, so can i get all those Process
Ids some how...

This class will help you to kill processes:
http://developer.android.com/reference/android/os/Process.html
This gives you a list of currently running processes:
ActivityManager.getRunningAppProcesses();
The list contains ActivityManager.RunningAppProcessInfo objects which store the pid. You can then kill the processes via
Process.killProcess(pid);
You need the proper permissions to do that. Android should throw an exception if you try to kill a process without the proper permissions and tell you what permission you need.

check this way if it solves your purpose:
ArrayList<PackageInfo> res = new ArrayList<PackageInfo>();
PackageManager pm = context.getApplicationContext().getPackageManager();
List<PackageInfo> packs = pm.getInstalledPackages(0);
packs.get(pos).gids;
packs.get(pos).sharedUserId;

You can get information about all running processes using ActivityManager. Refer following code:
ActivityManager am = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
List<RunningAppProcessInfo> list = am.getRunningAppProcesses();
for (RunningAppProcessInfo proc : list) {
Log.v("Proccess", proc.processName + " : " + proc.pid);
}
Multiple applications can be running in the same process, so it would be better to use RunninAppProcessInfo.pkgList over RunninAppProcessInfo.processName.