带Runnable的天文台不起作用

Question

您好我为我的游戏创建了一个天文台。问题是我创建了2个类。这不起作用。我有一个Exepction。

 public class Crono1 extends Activity implements Callback{

public TextView txtTiempo;
public boolean detenido;
public boolean pausado;
private Handler handler;
String cronometro;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    txtTiempo = (TextView) findViewById(R.id.ConTiempo);
    final Button btn = (Button) findViewById(R.id.BtnAccion);
    final Button btnDetener = (Button) findViewById(R.id.BtnDetener);
    detenido = false;
    pausado = true;
    handler = new Handler(this);

    btn.setOnClickListener(new OnClickListener() {

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

            Tiempo w = new Tiempo (handler);
            Thread t = new Thread (w);
            t.start();
        }
    });

    btnDetener.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            detenido = true;
            txtTiempo.setText("00:00:00:00");
        }
    });
}
@Override
public boolean handleMessage(Message msg) {
  TextView texto = (TextView) findViewById(R.id.ConTiempo);

  Integer text = (Integer) msg.obj;
    texto.setText(text+"");
    Log.d("ENTRO",msg.obj.toString());
    return true; 
}

---

 public class Time implements Runnable{
public TextView txtTiempo;
public boolean detenido;
public boolean pausado;
int centesimas = 00,minutos=00, segundos=00, horas=00;
String cronometro;
private Handler handler;

public Time (Handler handler){
    this.handler = handler;
 }

@Override
public void run (){
    while(!detenido)
    {
        while(!pausado)
        {
            try {
                //if(centesimas == 99){
                    //centesimas = 00;
                    segundos++;
                //}
                if (segundos == 59) {
                    segundos = 00;
                    minutos++;
                }
                if (minutos == 59) {
                    minutos = 00;
                    //horas++;
                }
                centesimas++;
                //cronometro = /*horas + ":" +*/ minutos + ":" + segundos /*+ ":" + centesimas*/;
                sendMsg (minutos + ":" + segundos);
                handler.sendEmptyMessage(0);
                Thread.sleep(900);
            } catch (Exception ex) {
                ex.printStackTrace();
            }

        }

}

private void sendMsg(String string)
{
    Message message = new Message ();
    message.obj = string;
    handler.sendMessage(message);
}

Exepction是“Unchaught handler”和“ClassCastExeption”。我的错是什么？如何做：如果时间是1:50，完成应用程序或使用Intent ??