TextView and change text with button ( Android )

 package com.test.android;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class Test extends Activity { 
     private TextView t1;
     private Button btn;


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

        t1 = new TextView(this);
        t1 = (TextView)findViewById(R.id.text1);
        t1.setText(" Hello ");

       addBtnListener();

    }
    private void addBtnListener() {
        btn = (Button) findViewById(R.id.button1);
        btn.setOnClickListener(new OnClickListener(){
            public void onClick(View arg0){
                t1.setText(" My name is Android ");
            }
        });
    }
}