[Android SQLite]データストレージとアクセス-外部ストレージ

public class SD_Demo extends Activity implements OnClickListener
{
	private StringBuilder randomNumBersString = null;
	
	private TextView displayView = null;
	
	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main1);
		setupViews();
	}

	private void setupViews()
	{
		displayView = (TextView) findViewById(R.id.display);
		findViewById(R.id.random).setOnClickListener(this);
		findViewById(R.id.write).setOnClickListener(this);
		randomNumBersString = new StringBuilder();
	}

	@Override
	public void onClick(View v)
	{
		switch (v.getId())
		{
			case R.id.random:
				for (int i = 0; i < 10; i++)
				{
					randomNumBersString.append(Math.random()+"
");
				}
				displayView.setText(randomNumBersString.toString());
				break;
				
			case R.id.write:
				String fileName = "SdcardFile-"+System.currentTimeMillis()+".txt";;
				boolean sdCardExist = Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED); 
				File dir = null;
				if (sdCardExist)
				{
					dir = new File( Environment.getExternalStorageDirectory().toString() + File.separator + "123321");
					if (!dir.exists())
					{
						dir.mkdirs();
					}
				}
				if (dir.exists() && dir.canWrite())
				{
					File newFile = new File(dir.getAbsolutePath()+ "/" + fileName);
					FileOutputStream fos = null;
					try
					{
						newFile.createNewFile();
						if (newFile.exists() && newFile.canWrite())
						{
							fos = new FileOutputStream(newFile);
							fos.write(randomNumBersString.toString().getBytes());
							displayView.setText(String.format("%s    SD ", fileName))	;
						}
					} catch (IOException e)
					{
						e.printStackTrace();
					}finally
					{
						if (fos != null)
						{
							try
							{
								fos.flush();
								fos.close();
							} catch (IOException e)
							{
								e.printStackTrace();
							}
						}
					}
				}
				break;
		}
	}
}