첫화면에서 db파일이 존재하는지 체크한후 각각 다른 화면으로 이동하게 하려는데요
	DB가 있어도 없는걸로되네요 자꾸,,,도와주세요~
protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		folder = new File("/data/data/com.example.DKStudentCard/databases/");
		if (!folder.exists()) {
			folder.mkdir();
		}
		file = new File("/data/data/com.example.DKStudentCard/databases/StudentCard.db");
		Handler handler = new Handler() {
			public void handleMessage(Message msg) {
				super.handleMessage(msg);
				if (file.exists()) {
					System.out.println("있음");
					startActivity(new Intent(MainActivity.this,
							StudentCard.class));
				} else {
					System.out.println("없음");
					startActivity(new Intent(MainActivity.this,
							Certification.class));
				}
				finish();
			}
		};
		handler.sendEmptyMessageDelayed(0, 1000);
	}