Making an Android application that cannot be uninstalled/deleted
android, java, security
Solution
This sounds more akin to Malware-like behaviour than that of a regular Android application, anyway:
For a regular Android application, I'd imagine that making it 'uninstallable' is near enough impossible to achieve - try to contemplate what the state of the Android app market would be like right now if this were possible!
On the other hand, if privileged control (root access) was available then this might be a possibility - an example of that could be like how wireless carriers implement bundled software. However, like I mentioned, there is no regular avenue available for applications released via. the Android market to achieve what you've asked, it should be pretty clear to you why...
Problem
I want to make a security app for Android phones. Basically, I don't want anyone to be able to un-install it without having to enter a specific password first. Also, is there a way to prevent the app from being stopped manually (like being closed via. Taskmanager) etc?