Я новичок в разработке Android. здесь я копирую свою базу данных из браузера баз данных SQLite в мою системную базу данных. Но когда я пытаюсь открыть эту вновь созданную базу данных ... я получаю сообщение об ошибке ...
вот мой код
DBAdapter.java
public class DBAdapter extends SQLiteOpenHelper
{
private static String DB_PATH = "/data/data/com.xyz.app.demo/databases/";
private static String DB_NAME = "QuestionsDB";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase myDataBase;
private final Context myContext;
public DBAdapter(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public Cursor getAllTitles()
{
return myDataBase.query("Qus", new String[] {
"_id",
"quesion",
"XCol",
"Ycol",
"option",
"intern",
"answer",
"weight"},
null,
null,
null,
null,
null);
}
а также
questionform.java
public class questionform extends Activity{
public void onCreate(Bundle icicle)
{
super.onCreate(icicle);
setContentView(R.layout.qus_screen);
final DBAdapter db = new DBAdapter(this);
db.openDataBase();
Cursor c = db.getAllTitles();
if (c.moveToFirst())
{
do
{
DisplayTitle(c);
} while (c.moveToNext());
}
db.close();
}
private void DisplayTitle(Cursor c)
{
Toast.makeText(questionform.this,c.getString(1),Toast.LENGTH_LONG).show();
}
}
Обновление
новый код для questionform.java:
public void onCreate(Bundle icicle)
{
super.onCreate(icicle);
setContentView(R.layout.qus_screen);
final DBAdapter db = new DBAdapter(this);
try {
db.createDataBase();
} catch (IOException e) {
// TODO Auto-generated catch block
}
db.openDataBase();
Cursor c = db.getAllTitles();
if (c.moveToFirst())
{
do
{
DisplayTitle(c);
} while (c.moveToNext());
}
db.close();
}