I can't change the textview text by pressing a button

Hello all I am struggling to change the textview text dynamically in android studio i get 0 errors but when i am testing the program runs but at the time i press the button program crashes /////////

public class MyFragment extends Fragment { TextView tv;

Button[] btn = new Button[30];
Button[] btn1 = new Button[30];
Button[] btn2 = new Button[30];

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // TODO Auto-generated method stub View myFragmentView = inflater.inflate(R.layout.fragmentlayout, container, false);

for (int i = 0; i < 30; i++) { btn[i] = new Button(getActivity()); btn[i].setText("1"); btn[i].setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); btn[i].setVisibility(View.VISIBLE); btn[i].setId(i); linearLayout.addView(btn[i]);

btn[2].setOnClickListener(btnOnClickListener);

Button.OnClickListener btnOnClickListener = new Button.OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub


        if (v == btn[2]) {

            tv.setText(btn[2].getText());
        }

    }
};

/////////////

This is not the all parts of the code but i can't share all of the program itself, but these are all the parts about my problem. If you have anything to say please say it. Thanks in advance