Android : android pdf opening in app

im an amator in android and java programing , i underestand button casting and some other views and hot to code for button workin but i dont know system file commonds , i want to create an app that just views a pdf file . i have placed aaaaa.pdf to assets folder in my app. can any master write for me MainActivity.java all codes ?

leave this below codes (it is for question body error ignoring )

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

Special Thanks