android java如何将信息打印在屏幕上？我现在用logcat，但是程序怎么不运行呢？

public class TestActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); char[] src = new char[1024*1024]; char[] dst = new char[1024*1024]; int i; for (i = 0; i < 30; i++) { long start = android.os.SystemClock.uptimeMillis(); System.arraycopy(src, 0, dst, 0, 1024*1024); long end = android.os.SystemClock.uptimeMillis(); Log.v("Test", "cost time: " + (end - start)); } }}