Question

我正在使用SQLITE数据库开发一个Android应用程序，目前正面临一个问题。以下是我的代码

    public class DatabaseHelper extends SQLiteOpenHelper {
// Log cat tag
private static final String LOG = DatabaseHelper.class.getName();

// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "quotes_hub";

// Table Name
private static final String TABLE_QUOTE = "quote";

private Context context;
SQLiteDatabase db1;
// Quote Table - column names
private static final String KEY_ID = "id";
private static final String KEY_TEXT = "text";
private static final String KEY_FAVOURITE = "favourite";
// table create statement
private static final String CREATE_TABLE_QUOTE = "create table "
        + TABLE_QUOTE + " (" + KEY_ID
        + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_TEXT + " TEXT, "
        + KEY_FAVOURITE + " TEXT DEFAULT 'NO'" + ")";

public DatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    this.context = context;
    System.out.println("sdfsdfsfsdfsfdsfs"+CREATE_TABLE_QUOTE);
}

public void onCreate(SQLiteDatabase db) {
    System.out.println("************************************");
    db.execSQL(CREATE_TABLE_QUOTE);
    try {
        int number =insertFromFile(context, R.raw.dump);
        System.out.println("========================================= "+number );
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
}

// creating exam entry in database
public long createQuote(Quote quote) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_TEXT, quote.getText());
    values.put(KEY_FAVOURITE, quote.getIsFavourite());
    // insert row
    long rowId = db.insert(TABLE_QUOTE, null, values);

    return rowId;
}

// retrieving all entries from quote table
public List<Quote> getAllQuotes() {
    List<Quote> quotes = new ArrayList<Quote>();
    String selectQuery = "SELECT  * FROM " + TABLE_QUOTE;

    Log.e(LOG, selectQuery);

    SQLiteDatabase db = this.getReadableDatabase();
    if(db == null){
    System.out.println("this is the database "+db );
    }
    Cursor c = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (c.moveToFirst()) {
        do {
            Quote quote = new Quote();
            quote.setText(c.getString((c.getColumnIndex(KEY_TEXT))));
            quote.setIsFavourite(c.getString((c
                    .getColumnIndex(KEY_FAVOURITE))));

            // adding quote to quotes list
            quotes.add(quote);
        } while (c.moveToNext());
    }

    return quotes;
}

public int insertFromFile(Context context, int resourceId) throws IOException {
    // Reseting Counter
    int result = 0;
    SQLiteDatabase db = this.getWritableDatabase();
    // Open the resource
    InputStream insertsStream = context.getResources().openRawResource(resourceId);
    BufferedReader insertReader = new BufferedReader(new InputStreamReader(insertsStream));

    // Iterate through lines (assuming each insert has its own line and theres no other stuff)
    while (insertReader.ready()) {
        String insertStmt = insertReader.readLine();
        db.execSQL(insertStmt);
        result++;
    }
    insertReader.close();

    // returning number of inserted rows
    return result;
}
   }

上面代码的问题是即使在调用getReadableDatabase（）方法之后也没有调用onCreate方法。当我运行应用程序时，它给出了一个错误，指出名为“Quote”的表不存在。请帮帮我。

谢谢。

Answer 1

onCreate（）未被调用 - 它的功能不是错误;）只有在第一次装箱数据库时才会调用此方法 - 从您的设备卸载应用程序并在下次启动时调用它。

或者你可以实现onUpgrade（）方法 - 当你增加数据库版本时（当你的常量高于db中保存的常量时）会调用这个方法。

SQLITE onCreate不会被调用

1 个答案: