Develop Reference

How to uninstall app which is set by password?

I developed one parent and child communication Android application in which I wanted to restrict the child from uninstalling application. I have one solution that uses DevicePolicyManager. But still the application can be uninstalled without asking for password. If I remove the Device Administrator permission from the settings, then application is uninstalled from device?
Can anyone provide the valid solution for this cause?

You cannot prevent a user from uninstalling an app, from within the app code itself.
There is suggestions here How to prevent an application from being uninstalled?, but they are not foolproof.
The way around this is to use an android device with lollipop and upwards, so you can create a user account.
On the admin account, install an app that requires a password to uninstall apps. They are on the market (and free) I've used them. Or write one yourself.
Then on the child's account allow them whatever privileges you want them to have. They will be unable to touch the apps and uninstall them, unless on the admin account and with the password required for that app to uninstall other apps.
I have tried and tested this and it works.

Is there a way to prevent a user to uninstall an app?

I'm making an android anti-thief app. I want to prevent a thief to uninstall the anti-thief app.
The app is a device administrator. So I used DeviceAdminReceiver.onDisabled
to start a “always on top” password prompt Activity (the password is setup by the user during the app configuration). This works fine.
But, Google Play rejected the app. Email extract:
Read through the Device and Network Abuse policy and make the
appropriate changes to your app. You’ll need to remove any
functionality that prevents a user from removing or uninstalling the
app from their device.
My Question:
What other ways can I use to prevent unauthorized user to:
uninstall my device administrator app ?
disable the device administrator permission ?
Thanks
EDIT: reformulate the question to clarify that the question is not about google play policy, but about alternative implementation.

Android permissions not requested after reinstall

I am testing my Android app on my own phone. When I first run it on my phone, it asks for permission to user my gmail account. When I reinstall my app, it no longer does that? I would like to make it so that it re-requests permission every time I reinstall the app for testing purposes. If, on the other hand, I change the package name, it re-requests the permission. Does anyone know how to do that? Much help would be appreciated!
Thanks!
Note: By reinstall, I mean both pressing the run button and actually resinstalling the application by first uninstalling via settings.

This is not an actual Android permission, it's actually an account access grant specific to AccountManager. Technically, when you uninstall an app all grants should be cleared, but this appears broken on some devices. If you have a rooted device or are using the emulator, you can find accounts.db (usually in /data/system/users/0/accounts.db on newer versions) and clear the grants and extras tables (that could affect other apps, so handle with care). If you don't, clearing the data for Google Account Manager and Google Play Services could help.

What do you mean by reinstall? Does reinstall simply meaning pressing the "run" button? Or are you actually uninstalling and reinstalling the application. Once the Android OS detects that a permission is needed, it will request it from the user. But after that first time, it won't ask again. If you completely uninstall the application from the device and then reinstall, it should work. I don't know of any other way you can bypass that.

How to prevent an application from being uninstalled?

I'm developing an application for parents to watch out for their children. So this application cannot be removed by the child. I need to know how to make it uninstallable or the user need password to remove that application.

Ankur,
I think the closest thing to what your looking for is the Device Administration feature introduced in 2.2.
Once the application is registered as a Device Administrator, it can't be uninstalled unless its unregistered. This will prevent the app from being uninstalled.
While the Device Admin API doesn't allow for password protection of this particular feature, you can password protect your application to prevent someone from tampering with the Device Admin features in the app.
I use an app called SeekDroid that has a similar functionality.

I've only seen one app that does this, its called Prey and is used to track lost phones and computers. The project is open source so you could go through their code and see how they do it or contact the developer and maybe they'll tell you how they do it.

Notify when Application uninstall from Android Device

I want to create an Application such that if it is uninstalled by user then I want to stop uninstallation of Application.
How I can do this ?
Thanks

You can't. There is no such event in Android. Also you can't stop uninstallation of your or any other app. For this you'll need some permissions that are only granted to system applications.

why? why? why? As a user, if I want to uninstall an app, then I no longer want it, and it should be uninstalled if I am uninstalling it. It should also not be reinstalled unless I exclusively do so.
But there are some applications which we cannot uninstall unless we have a rooted device. Those are the apps like market, Google maps, camera etc which are installed by the manufacturers. You would want to create an app which is so good and useful and then convince the manufacturers or service providers to preinstall the app and prevent the users from uninstalling it. Examples : Swype, Skype, Facebook, Twitter etc
But if the app is a normal app then I would recommend against such a thing.
For your question, you cannot do so unless you are the manufacturer.