如何使用不同类中的两个onClickListener引用布局

My question is in reference to the OnclickListner and java classes. I have an xml layout with two buttons; one (when clicked) triggers the "date" class, the other triggers the "email" class. The Email button is working fine, however when I try to set an on click listener to the "date" button, the app crashes(When Triggered). My goal is to be able to click the date button, display the datepicker. Here is my code. Hopefully this is enough information for anyone to assist me, Thanks everyone.My question is in reference to the OnclickListn