how to start an activity in another module explicitly

You can use the Class.forName(), it worked for me when i was needed to start activity which is in another module in my project.

 Intent intent = null;
    try {
        intent = new Intent(this, 
           Class.forName("ir.sibvas.testlibary1.HelloWorldActivity"));
        startActivity(intent);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }