这个代码编译器不报错，但是运行时出现停止运行的显示怎么回事

public class MainActivity extends Activity implements OnClickListener,Runnable{

private Button bt;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

bt=(Button) findViewById(R.id.button1);

bt.setOnClickListener(this);

}

@Override

public void run() {

bt.setText("改变");

}

@Override

public void onClick(View v) {

Thread t=new Thread(new MainActivity());

t.start();

Toast.makeText(getApplication(), "监听到点击事件", 1).show();

}

}