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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。刪除行後刷新ListView
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;
}
}
首先你得到所有的db.getRanking（），但你是不刪除數據庫中你只在列表視圖中刪除，請在你的刪除代碼添加DbHelper類@ Boqn – Joy
你只從listRanking刪除項目，但沒有更新數據庫。 –