似乎 SQLite table 由于未知原因已停止填充

Question

应用程序工作正常，但方法 Cursor.moveToFirst() 开始返回 false，并且应用程序的列表已停止出现在片段中。

我想这一切都是从我改变了一个constat的名字开始的：IMAGE_URI到IMAGE_URL，imageUri到imageUrl。虽然不确定。

我尝试调试和搜索类似案例，但原因多种多样。调试时，我无法到达 SQLiteHelper class 的 onCreate 以了解在 table 填充期间发生了什么（似乎 table 存在，因为正在创建 table 的空数据库），因此我无法调试或搜索类似问题，因为在 Logcat.[=22= 中找不到相关输出]

获取数据库

此class用于与SQLiteOpenHelperclass的一些通信。

public class GetDatabase {

    private static final int DB_VERSION = 1; //required for the constructor
    public static final String dbName = "moviesList";

    private SQLiteOpenHelper sqLiteOpenHelper;
    private SQLiteDatabase db ;

    public GetDatabase(Context context) {
        Log.d("GetDatabase", "Cont.");

        this.sqLiteOpenHelper = new SQLiteHelper(context, dbName, null, DB_VERSION);
    }

    public void open() {
       db = sqLiteOpenHelper.getWritableDatabase();
    }

    public void close() {
        if (sqLiteOpenHelper != null) {
            sqLiteOpenHelper.close();
        }
    }

    public ArrayList<Movie> getMovies() {
        String[] columns = {
                Movie.ID,
                Movie.TITLE,
                Movie.IMAGE_URL,
                Movie.RATING,
                Movie.RELEASE_YEAR,
                Movie.GENRE
        };

        // sorting orders
        String sortOrder =
                Movie.RELEASE_YEAR + " ASC";
        ArrayList<Movie> moviesList = new ArrayList<>();

        Cursor cursor = db.query(TABLE_NAME, //Table to query
                columns,
                null,
                null,
                null,
                null,
                sortOrder);

        if (cursor.moveToFirst()) {
            do {
                Movie movie = new Movie();
                movie.setMovieId(Integer.parseInt(cursor.getString(cursor.getColumnIndex(Movie.ID))));
                movie.setTitle(cursor.getString(cursor.getColumnIndex(Movie.TITLE)));
                movie.setImageUrl(cursor.getString(cursor.getColumnIndex(Movie.IMAGE_URL)));
                movie.setRating(cursor.getDouble(cursor.getColumnIndex(Movie.RATING)));
                movie.setReleaseYear(cursor.getInt(cursor.getColumnIndex(Movie.RELEASE_YEAR)));
                movie.setGenre(cursor.getString(cursor.getColumnIndex(Movie.GENRE)));
                // Adding a movie to the list
                moviesList.add(movie);
            } while (cursor.moveToNext());
        }
        Log.d(TAG, "The movies list from sqlite: " + moviesList);
        cursor.close();
        db.close();

        return moviesList;
    }

    private Cursor getData(int id) {
        return db.rawQuery( "select * from " + TABLE_NAME + " where id="+id+"", null );
    }

    public Cursor getMovieDetails(int movieId) {// For viewing details of a specific item

        Cursor cursor = getData(movieId);
        cursor.moveToFirst();

        return cursor;
    }
}

SQliteHelper

SQLiteOpenHelper class

public class SQLiteHelper extends SQLiteOpenHelper {

    private static final String DB_NAME = "movies.db";
    private static final int DB_VERSION = 1; //required for the constructor
    private static final String TABLE_NAME = "movies";

    private String fileName = "movies.json";
    private String appName = "MoviesList";
    private String path = getExternalStorageDirectory() + "/" + appName + "/" + fileName;

    private String jsonString = null;

    private SQLiteDatabase db;

    // The cont. for saving to SQLite .Called from SplashActivity after downloading the JSON
    public SQLiteHelper(Context context, String dbName, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        Log.d(TAG, "At SQLiteHelper");

        createSQLIteTable(db);
        if(tableIsEmpty(db)) {
            try {
                parseJsonAndInsertToSQLIte(db);
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

    private void createSQLIteTable(SQLiteDatabase db) {

        //creating a table for SQLite
        String CREATE_SQL_TABLE_STRING = "CREATE TABLE IF NOT EXISTS "+TABLE_NAME
                + " ("
                + Movie.ID + " INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL ,"
                + Movie.TITLE + " TEXT,"
                + Movie.IMAGE_URL + " TEXT,"
                + Movie.RATING + " TEXT,"
                + Movie.RELEASE_YEAR + " TEXT,"
                + Movie.GENRE + " TEXT "
                + ")";

        Log.i(TAG,"created sql table: "+CREATE_SQL_TABLE_STRING);

        db.execSQL(CREATE_SQL_TABLE_STRING);
    }

    private void parseJsonAndInsertToSQLIte(SQLiteDatabase db) throws JSONException {
        // parsing the json
        String jsonString = getJsonFileData();
        JSONArray moviesArray = new JSONArray(jsonString);
        ContentValues insertValues;

        for (int i = 0; i < moviesArray.length(); i++) {

            JSONObject jsonObject = moviesArray.getJSONObject(i);

            String title = jsonObject.getString("title");
            String imageUrl = jsonObject.getString("imageUrl");
            String rating = jsonObject.getString("rating");
            String releaseYear = jsonObject.getString("releaseYear");
            String genre = jsonObject.getString("genre");

            insertValues = new ContentValues();

            insertValues.put(Movie.TITLE, title);
            insertValues.put(Movie.IMAGE_URL, imageUrl);
            insertValues.put(Movie.RATING, rating);
            insertValues.put(Movie.RELEASE_YEAR, releaseYear);
            insertValues.put(Movie.GENRE, genre);
            long res = db.insert(TABLE_NAME, null, insertValues);

            Log.i(TAG, "parsed and inserted to sql - row: " + res);
        }
    }

    private String getJsonFileData() {
        //loading the jsonString
        try {
            InputStream in = new FileInputStream(new File(path));
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            StringBuilder output = new StringBuilder();
            while ((jsonString = reader.readLine()) != null) {
                output.append(jsonString);
            }
            System.out.println(output.toString());   //Prints the string content read from input stream

            jsonString = output.toString();
            Log.d(TAG, "the jsonString was loaded");
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        return jsonString;
    }
}

如果我不解决这个问题，我认为整个应用程序毫无价值，因为我不知道需要更正什么错误。

谢谢！

Answer 1

从设置中清除您的应用程序数据并重新运行您的应用程序。由于您在数据库列中进行了更改，除非您清除数据，否则它不会反映出来。

或者

正确处理数据库版本。每次更改数据库结构时，删除 onUpgrade 方法中的所有表并增加数据库版本。

编辑：清除数据window

似乎 SQLite table 由于未知原因已停止填充

It seems that the SQLite table had stopped being populated for unknown reason

android

sqlite

sqliteopenhelper