刪除行後刷新ListView

Question

對於最近兩天我試圖刪除listRow項目沒有成功。 我設法清除listRow項目與此代碼，但是當我再次啓動應用程序時，我再次看到他們不刪除。所以請如果有人可以幫助，我會非常beholden。

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
    @Override 
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
listRanking.remove(position); 

     adapter.notifyDataSetChanged(); 

    } 
}); 

這是我的ListView活動。

public class Score extends AppCompatActivity { 


    ListView listView; 


    @Override 
    protected void onCreate(final Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_score); 
     listView = (ListView) findViewById(lstRanking); 


     final DbHelper db = new DbHelper(this); 
     final List<Ranking> listRanking = db.getRanking(); 
     if (listRanking.size() > 0) { 
      final CustomAdapter adapter = new CustomAdapter(this, listRanking); 
      listView.setAdapter(adapter); 

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
    @Override 
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
listRanking.remove(position); 

     adapter.notifyDataSetChanged(); 

    } 
}); 

這是我的自定義適配器。

public class CustomAdapter extends BaseAdapter { 

    private Context context; 
    private List<Ranking> lstRanking; 


    public CustomAdapter(Context context, List<Ranking> lstRanking) { 
     this.context = context; 
     this.lstRanking = lstRanking; 
    } 

    @Override 
    public int getCount() { 
     return lstRanking.size(); 
    } 

    @Override 
    public Object getItem(int position) { 
     return lstRanking.get(position); 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

    @Override 
    public View getView(final int position, View convertView, final ViewGroup parent) { 

     LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     View view = inflater.inflate(R.layout.row, null); 
     ImageView imgTop = (ImageView) view.findViewById(R.id.imgTop); 
     TextView txttop = (TextView) view.findViewById(R.id.txtPobeditel); 

     if (position == 0) 
      imgTop.setImageResource(R.drawable.devinci_spartan_2015); 


     else if (position == 1) 
      imgTop.setImageResource(R.drawable.giant_glory_2016); 
else 
      imgTop.setImageResource(R.drawable.trek_session_9_9); 

     txttop.setText(String.valueOf(lstRanking.get(position).getScore())); 


     return view; 
    } 



} 

這是我的數據庫：

public class DbHelper extends SQLiteOpenHelper { 

    private static String DB_NAME = "New Database.db"; 
    private static String DB_PATH = ""; 
    private Context mContext = null; 
    private SQLiteDatabase mDatabase; 


    public DbHelper(Context context) { 
     super(context, DB_NAME, null, 1); 

     DB_PATH = context.getApplicationInfo().dataDir + "/databases/"; 
     File file = new File(DB_PATH + "New Database.db"); 
     if (file.exists()) 
      openDataBase(); 

     this.mContext = context; 
    } 

    public void openDataBase() { 
     String myPath = DB_PATH + DB_NAME; 
     mDatabase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 

    } 

    public void CopyDataBase() throws IOException { 
     try { 
      InputStream myInput = mContext.getAssets().open(DB_NAME); 
      String outputFileName = DB_PATH + DB_NAME; 
      OutputStream myOutput = new FileOutputStream(outputFileName); 
      byte[] buffer = new byte[1024]; 
      int length; 
      while ((length = myInput.read(buffer)) > 0) 
       myOutput.write(buffer, 0, length); 
      myOutput.flush(); 
      myOutput.close(); 
      myInput.close(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

    private boolean checkDatabase() { 
     SQLiteDatabase tempDB = null; 
     try { 
      String myPath = DB_PATH + DB_NAME; 
      tempDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 
     } catch (SQLiteException e) { 
      e.printStackTrace(); 

     } 
     if (tempDB != null) 
      tempDB.close(); 
     return tempDB != null ? true : false; 

    } 

    public void createDatabase() throws IOException { 
     boolean isDBExists = checkDatabase(); 
     if (isDBExists) { 

     } else { 


      this.getReadableDatabase(); 
      try { 
       CopyDataBase(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 


    @Override 
    public void onCreate(SQLiteDatabase db) { 

    } 

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

    } 


    public List<Question> getAllQuestion() { 
     List<Question> listQuestion = new ArrayList<>(); 
     SQLiteDatabase db = this.getWritableDatabase(); 
     Cursor c; 
     try { 
      c = db.rawQuery("SELECT * FROM Question ORDER BY Random()", null); 
      if (c == null) return null; 
      c.moveToFirst(); 
      do { 
       int Id = c.getInt(c.getColumnIndex("ID")); 
       String Image = c.getString(c.getColumnIndex("Image")); 
       String AnswerA = c.getString(c.getColumnIndex("AnswerA")); 
       String AnswerB = c.getString(c.getColumnIndex("AnswerB")); 
       String AnswerC = c.getString(c.getColumnIndex("AnswerC")); 
       String AnswerD = c.getString(c.getColumnIndex("AnswerD")); 
       String CorrectAnswer = c.getString(c.getColumnIndex("CorrectAnswer")); 
       Question question = new Question(Id, Image, AnswerA, AnswerB, AnswerC, AnswerD, CorrectAnswer); 
       listQuestion.add(question); 


      } 
      while (c.moveToNext()); 
      c.close(); 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
     db.close(); 
     return listQuestion; 

    } 

    public List<Question> getQuestionMode(String mode) { 
     List<Question> listQuestion = new ArrayList<>(); 
     SQLiteDatabase db = this.getWritableDatabase(); 
     Cursor c; 
     int limit = 0; 
     if (mode.equals(Common.MODE.EASY.toString())) 
      limit = 30; 
     else if (mode.equals(Common.MODE.MEDIUM.toString())) 
      limit = 50; 
     else if (mode.equals(Common.MODE.HARD.toString())) 
      limit = 100; 

     try { 
      c = db.rawQuery(String.format("SELECT * FROM Question ORDER BY Random() LIMIT %d", limit), null); 
      if (c == null) return null; 
      c.moveToFirst(); 
      do { 
       int Id = c.getInt(c.getColumnIndex("ID")); 
       String Image = c.getString(c.getColumnIndex("Image")); 
       String AnswerA = c.getString(c.getColumnIndex("AnswerA")); 
       String AnswerB = c.getString(c.getColumnIndex("AnswerB")); 
       String AnswerC = c.getString(c.getColumnIndex("AnswerC")); 
       String AnswerD = c.getString(c.getColumnIndex("AnswerD")); 
       String CorrectAnswer = c.getString(c.getColumnIndex("CorrectAnswer")); 
       Question question = new Question(Id, Image, AnswerA, AnswerB, AnswerC, AnswerD, CorrectAnswer); 
       listQuestion.add(question); 


      } 
      while (c.moveToNext()); 
      c.close(); 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
     db.close(); 
     return listQuestion; 

    } 


    public void insertScore(int Score) { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     ContentValues contentValues = new ContentValues(); 
     contentValues.put("Score", Score); 
     db.insert("Ranking", null, contentValues); 
    } 


    public List<Ranking> getRanking() { 
     List<Ranking> listRanking = new ArrayList<>(); 
     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor c; 
     try { 
      c = db.rawQuery("SELECT * FROM Ranking ORDER BY Score DESC;", null); 
      if (c == null) return null; 
      c.moveToNext(); 
      do { 
       int Id = c.getInt(c.getColumnIndex("Id")); 
       int Score = c.getInt(c.getColumnIndex("Score")); 
       Ranking ranking = new Ranking(Id, Score); 
       listRanking.add(ranking); 

      } 
      while (c.moveToNext()); 
      c.close(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

     db.close(); 
     return listRanking; 
    } 


    } 

Answer 1

適配器不知道你從列表中刪除的項目。

add方法更新適配器中的列表，然後調用notify。

<adapter> 
public void setListRankings(List<Ranking> lstRanking) { 
    this.lstRanking = lstRanking; 
} 

然後

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
    @Override 
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
     listRanking.remove(position); 
     adapter.setListRankings(listRanking); 
     adapter.notifyDataSetChanged(); 

    } 
}); 

Answer 2

除了什麼@Matthew希勒說的方法deleteRanking添加到您DbHelper

public void deleteRanking(long idRanking) { 
    SQLiteDatabase db = getWritableDatabase(); 
    db.delete("Ranking", "Id=?", new String[] {Long.toString(idRanking)}); 
    db.close(); 
} 

，並稱之爲：

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
@Override 
public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
    db.deleteRanking(listRanking.get(position).getId());//<------Here 
    listRanking.remove(position); 
    adapter.setListRankings(listRanking); 
    adapter.notifyDataSetChanged(); 

} 
});