Change main activity in code

How to change main activity at application startup in Android?

I want to implement lock screen asking for password, before allow user to interact with application. Password 开发者_运维问答screen can be turned of in application's settings and in such case (when application should not ask for password) I want to start Main application activity not Password activity. How it is possible?

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In the onCreate of the Main activity, check preference and if password is on startActivity to load the Password activity.

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First, I am new to Android programming so bear with me!

If I was doing it, I would have created another activity that would be the main activity (set in the AndroidManifest.xml file) and inside the onCreate() event I would have checked that parameter in your setting file and depending on its value, I would have launched the password activity or the other one.