Question

我正在创建一个animeList-app，就像网站myAnimeList。

我的问题是我在我的数据库中显示的数据是“随机的”。有些数据没有显示或不正确，如果我点击一个项目（如动漫“海贼王”）Toast.makeText（myAnime_completed.get（position）.getName（））;将从db中给我一个完全随机的项目。

我有一个databaseHelper，我在其中加载数据。

        //CREATE TABLE MYANIME
        String CREATE_TABLE_MYANIME = "CREATE TABLE myAnime (" +
                "id INTEGER PRIMARY KEY AUTOINCREMENT," +
                "name TEXT," +
                "description TEXT," +
                "episodes INTEGER," +
                "genre TEXT," +
                "rating INTEGER," +
                "episodesWatched INTEGER," +
                "stateId INTEGER)";
        db.execSQL(CREATE_TABLE_MYANIME);       

private void insertMyAnime(SQLiteDatabase db) {
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('One Piece', 'GUUD', 700, 'brut', 0, 50, 2);");
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('Death Note', 'GUUD TUU', 35, 'thriller', 0, 50, 1);");
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('Fairy Tail', 'GUUD TUU', 35, 'thriller', 0, 50, 2);");
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('Naruto', 'GUUD TUU', 35, 'thriller', 0, 50, 1);");
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('Bleach', 'GUUD TUU', 35, 'thriller', 0, 50, 3);");
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('No Game No Life', 'GUUD TUU', 35, 'thriller', 0, 50, 3);");
        db.execSQL("INSERT INTO myAnime (name, description, episodes, genre, rating, episodesWatched, stateId) VALUES ('Kill la Kill', 'GUUD TUU', 35, 'thriller', 0, 50, 3);");
    }

在此之后，我尝试将数据分成不同的类别：观看，完成，暂停，放弃并计划观看。

public MyAnime getMyAnimeByID(int animeId) {
        SQLiteDatabase db = this.getReadableDatabase();
        MyAnime myAnime = new MyAnime();
        Cursor cursor = db.query("myAnime", new String[] { "id", "name",
                "description", "episodes", "genre", "rating",
                "episodesWatched", "stateId" }, "id = ?",
                new String[] { String.valueOf(animeId) }, null, null, null);
        if (cursor.moveToFirst()) {
            myAnime = new MyAnime(cursor.getInt(0), cursor.getString(1),
                    cursor.getString(2), cursor.getInt(3), cursor.getString(4),
                    cursor.getInt(5), cursor.getInt(6), cursor.getInt(7));
        }
        cursor.close();
        db.close();
        return myAnime;
    }

    public List<MyAnime> getMyAnimes_watching() {
        List<MyAnime> myAnimeList = new ArrayList<MyAnime>();
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query("myAnime", 
                new String[] { "id" }, "stateId = ?", 
                new String[] { String.valueOf(1)}, null, null, null);

        if (cursor.moveToFirst()) {
            do {
                myAnimeList.add(getMyAnimeByID(cursor.getInt(0)));
            } while (cursor.moveToNext());
        }

        cursor.close();
        db.close();
        return myAnimeList;
    }

    public List<MyAnime> getMyAnimes_completed() {
        List<MyAnime> myAnimeList = new ArrayList<MyAnime>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query("myAnime", new String[] { "id" },
                "stateId = ?", new String[] { String.valueOf(2)}, null, null,
                null);
        if (cursor.moveToFirst()) {
            do {
                myAnimeList.add(getMyAnimeByID(cursor.getInt(0)));
            } while (cursor.moveToNext());
        }
        cursor.close();
        db.close();
        return myAnimeList;
    }

然后在活动中我从db获取数据：

//FILL LISTVIEW COMPLETED
    final List<MyAnime> myAnime_completed = db.getMyAnimes_completed();    
    ArrayAdapter<MyAnime> adapter_completed = new ArrayAdapter<MyAnime>(this, android.R.layout.simple_list_item_1, myAnime_completed);

    ListView lvCompleted = (ListView) findViewById(R.id.myAnime_completed);
    lvCompleted.setAdapter(adapter_completed);

    lvCompleted.setOnItemClickListener(
            new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parentView, 
                            View childView, int position, long id) {

                    show(myAnime_completed.get(position).getName());
                    //goToNextActivity(myAnime_completed.get(position).getId());

                }
    });

说实话，我是一名学生，我意识到这可能很容易解决，但对于那些没有多少经验的人来说，这是一个愚蠢的人。

我真的希望有人可以帮助我！

Answer 1

我假设函数show（...）显示吐司。根据给出的信息，看起来代码是正确的，如果单击按钮OnePiece，它看起来应该返回OnePiece。但是，我需要更多信息，我无法发表评论。我会在getMyAnimeByID上设置一个断点，然后逐步执行代码以确保它返回正确的行。

我想确保列表只显示stateId = 2的值。看起来你也不需要对它进行排序，以回应下面的答案。

这是一个偏离主题的建议：

if (cursor.moveToFirst()) {
        do {
            myAnimeList.add(getMyAnimeByID(cursor.getInt(0)));
        } while (cursor.moveToNext());
    }

可以缩减为

while (cursor.moveToNext()) {
   myAnimeList.add(...);
}

光标从索引-1开始。

Answer 2

创建游标时，您应该在查询中传递“Order By”参数。使用db.query方法，将第二个到最后一个null参数更改为您希望数据排序的列。该方法的签名是：

Cursor query(boolean distinct, String table, String[] columns,
        String selection, String[] selectionArgs, String groupBy,
        String having, String orderBy, String limit)

因此，您可以传入字符串值“stateId ASC”。

Android - 从db获取数据

2 个答案: