问使用android应用程序inventor显示计时器显示

EN

public class Countdown extends Activity  {   
private TextView txtStatus;  
private ImageView image;  


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


public void onResume() {   
    super.onResume();   
    setContentView(R.layout.main);  

    this.txtStatus = (TextView) this.findViewById(R.id.tv);  
    this.image = (ImageView) this.findViewById(R.id.image);  

    new CountDownTimer(60000, 1000) {

        public void onTick(long millisUntilFinished) {

            txtStatus.setText("seconds remaining: " + millisUntilFinished / 1000);
        }

        public void onFinish() {

            image.setVisibility(View.VISIBLE);
        }
    }.start();


}   

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:id="@+id/tv"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="60"
    />
<ImageView android:layout_height="wrap_content" android:visibility="gone"
 android:src="@drawable/icon" android:layout_width="wrap_content" android:id="@+id/image"></ImageView>
</LinearLayout>