Question

我正在从网站下载数据库。下载的数据库名为db.php 它将存储在名为FishingMatey.db的data / data / my.package.name / files下。数据库位于DDMS的文件系统中，我可以在SQLite Studio的PC上打开它。我的数据库中填充了正确的表格和正确的数据。这是我下载SQLite数据库的代码：

public boolean downloadDatabase() {
    try {
        // Log.d(TAG, "downloading database");
        URL url = new URL("http://myurl.com/db.php");

        // Open a connection to that URL */
        URLConnection ucon = url.openConnection();

        // Define InputStreams to read from the URLConnection
        InputStream is = ucon.getInputStream();
        BufferedInputStream bis = new BufferedInputStream(is);

        // Read bytes to the Buffer until there is nothing more to read(-1)
        ByteArrayBuffer baf = new ByteArrayBuffer(50);
        int current = 0;
        while ((current = bis.read()) != -1) {
            baf.append((byte) current);
        }

        // Convert the Bytes read to a String
        FileOutputStream fos = null;
        // Select storage location
        fos = this.context.openFileOutput(DATABASE_NAME, Context.MODE_PRIVATE);

        fos.write(baf.toByteArray());
        fos.close();
    } catch (IOException e) {
        Log.e("downloadDatabase", "downloadDatabase Error: ", e);
        return false;
    } catch (NullPointerException e) {
        Log.e("downloadDatabase", "downloadDatabase Error: ", e);
        return false;
    } catch (Exception e) {
        Log.e("downloadDatabase", "downloadDatabase Error: ", e);
        return false;
    }
    return true;
}

我的问题：我可以用数据库打开 SQLiteDatabase db = SQLiteDatabase.openDatabase("/data/data/com.example.menuswitcher/files/" + DATABASE_NAME, null, SQLiteDatabase.OPEN_READONLY);，但如果我输入db.query(DATABASE_TABLE_Bewirtschafter, null, null, null, null, null, null);，我会收到以下错误：

01-08 19:52:22.366: E/AndroidRuntime(6157): FATAL EXCEPTION: main
01-08 19:52:22.366: E/AndroidRuntime(6157): android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 1

以下是我在Activity中调用它的方式： this.b3.setOnClickListener（new OnClickListener（）{

        public void onClick(View v) {
            // TODO Auto-generated method stub
            DBAccess dbAccess = new DBAccess(HauptmenueActivity.this, 1, "FishingMatey.db");
            if (dbAccess.downloadDatabase()) {
                dbAccess.initDatabase();
                Cursor cur = dbAccess.createBewirtschafterAllCursor();
                Log.v("b3", cur.getString(cur.getColumnIndex("name")));
            } else {
                Log.e("b3", "Error!");
            }
        }
    });

有人知道为什么这不起作用吗？

Answer 1

android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 1

此错误表示您在尝试读取光标之前忘记调用cursor.moveToFirst()。

Cursor cursor = db.query(DATABASE_TABLE_Bewirtschafter, null, null, null, null, null, null);
if(cursor.moveToFirst()) {
    // Do something with the first row, if it exists
}

打开下载的SQLite数据库时出错

1 个答案: