Q:

How to change the color of a TextView in one activity by clicking a button in another? 

I have two activities, in activity(1) I have a TextView, in activity(2) I have a button.  I want to change the TextView color in activity(1) by clicking the button in activity(2) and save this color.  How can I do this? 

A:

You can save your color with Shared Preferences when your button is clicked and later get it : 
In activity 2 when your button is pressed : 
 PreferenceManager.getDefaultSharedPreferences(MainActivity.this)
        .edit()
        .putString(key, value).apply();

And in activity 1 get the value that you saved:
PreferenceManager.getDefaultSharedPreferences(DriverScreen.this).getString(key, "default value")

