Solution 1 :

In your MainActivity use this code:

  Intent intent = new Intent(MainActivity.this, Second.java);
  startActivity(intent);

Please read about “Intents”, I have added some links that will clear your concepts.
Previously asked question
Intent Types

Problem :

I have 2 actvities with a xml each but I don’t know how to switch to the second page with a button.

Can someone send me the code for the MainActivitie.java please (for a button)

I currently use the findView and onClick

Does this answer your question?