Opening transparent / conversational activity on top of another activity

Question

Is there a way to open a transparent or transparent activity so that you can see the previous activity behind it on the screen?

[Edit] To make the question clearer, I know how to create transparent activity. The problem is when I run it with intent, it clears the screen and you cannot see the previous activity.

This is how I get started.

    Intent intent = new Intent(MainActivity.this, DialogActivity.class); startActivity(intent);

thank