Creating a password field in android
I have an app that I'm creating that needs a password entry field/confirmation field and I have searched everywhere for answers. 

Here's the specifics:

Let's say that someone on the sidewalk asks to use your phone. What you can do is pull up the app I created and basically use it as a dialer. On the end of a call, I need the activity to be redirected to the password activity, which is in a separate activity from the MainActivity. What also happens is once the password activity is called, a WindowManager causes the home button and back buttons to redirect to the password activity until the correct password is entered. Once the correct password is entered, the app goes back to the MainActivity and is left alone until next time.

First off, I need someone to offer a website explaining the basic password part, if they can, or just explain in the answers below.

I spent a lot of time on planning this app and if you are confused with my explanation, then comment on what you need to be explained.
Creating a password field in android
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I have an app that I'm creating that needs a password entry field/confirmation field and I have searched everywhere for answers. 

Here's the specifics:

Let's say that someone on the sidewalk asks to use your phone. What you can do is pull up the app I created and basically use it as a dialer. On the end of a call, I need the activity to be redirected to the password activity, which is in a separate activity from the MainActivity. What also happens is once the password activity is called, a WindowManager causes the home button and back buttons to redirect to the password activity until the correct password is entered. Once the correct password is entered, the app goes back to the MainActivity and is left alone until next time.

First off, I need someone to offer a website explaining the basic password part, if they can, or just explain in the answers below.

I spent a lot of time on planning this app and if you are confused with my explanation, then comment on what you need to be explained.