我使用 onActivityResult（）在我的RecyclerView中插入数据，但是 notifyDataSetChanged（）不会更新RecyclerView。我做了一些搜索，但我无法为我找到决定。
只有当我返回并重新打开应用程序时，才会显示新数据。
如何更新观点？
这是我的 RecyclerViewFragment 代码：
public class RecyclerViewFragment extends Fragment{
View v;
private RecyclerView recyclerView;
private List<Deadline> deadlines;
DeadlineAdapter deadlineAdapter;
DbActivity db;
Cursor fullData;
LinearLayout empty;
String summary, date, time;
public RecyclerViewFragment() { // Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
v = inflater.inflate(R.layout.fragment_recycler_view, container, false);
recyclerView = v.findViewById(R.id.recycler_view);
empty = v.findViewById(R.id.empty);
db = new DbActivity(getContext());
fullData = db.getAllData();
if (fullData.getCount() > 0){
if (fullData.moveToFirst()) {
deadlines = new ArrayList<>();
int i = 1;
do {
String check = fullData.getString(4);
if (!check.startsWith("co")){
summary = fullData.getString(1);
date = fullData.getString(2);
time = fullData.getString(3);
String deadline = fullData.getString(4);
String labels = fullData.getString(5);
//String labels = "wtf";
deadlines.add(new Deadline(summary, date, time, deadline,
labels));
i++;
}
} while (fullData.moveToNext());
}
empty.setVisibility(View.GONE);
}
else {
deadlines = new ArrayList<>();
recyclerView.setVisibility(View.GONE);
empty.setVisibility(View.VISIBLE);
}
deadlineAdapter = new DeadlineAdapter(getContext(), deadlines);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(deadlineAdapter);
return v;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onActivityResult (int requestCode, int resultCode, Intent data) {
if (requestCode == Codes.INTENT_RESULT_CODE){
if(resultCode == Codes.INTENT_RESULT_CODE) {
DbActivity db = new DbActivity(getContext());
Cursor newDeadline = db.getAllData();
newDeadline.moveToLast();
summary = newDeadline.getString(1);
date = newDeadline.getString(2);
time = newDeadline.getString(3);
String deadline = newDeadline.getString(4);
String labels = newDeadline.getString(5);
deadlines.add(new Deadline(summary, date, time, deadline, labels));
deadlineAdapter.notifyDataSetChanged();
super.onActivityResult(requestCode, resultCode, data);
}
}
}
}
AddTaskActivity类：
public class AddTaskActivity extends AppCompatActivity {
int minute, hour, year, month, day, check;
String format, summary, date, time;
TextView setDate, setTime;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_task);
Toolbar toolbar = findViewById(R.id.toolbar_add_task_activity);
toolbar.setNavigationIcon(getResources().getDrawable(R.drawable.ic_back));
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
final EditText editText = findViewById(R.id.summary);
CharCountTextView charCountTextView = findViewById(R.id.tvTextCounter);
charCountTextView.setEditText(editText);
charCountTextView.setCharCountChangedListener(new CharCountTextView.CharCountChangedListener() {
@Override
public void onCountChanged(int countRemaining, boolean hasExceededLimit) {
//stop?
}
});
check = 0;
setDate = findViewById(R.id.setDate);
final Calendar currentDate = Calendar.getInstance();
year = currentDate.get(Calendar.YEAR);
month = currentDate.get(Calendar.MONTH) + 1;
day = currentDate.get(Calendar.DAY_OF_MONTH);
setDate.setText(day + "/" + month + "/" + year);
month -= 1;
currentDate.set(Calendar.DAY_OF_MONTH, day);
setDate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
DatePickerDialog datePickerDialog = new DatePickerDialog(AddTaskActivity.this, new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
monthOfYear += 1;
setDate.setText(dayOfMonth + "/" + monthOfYear + "/" + year);
}
}, year, month, day);
datePickerDialog.getDatePicker().setMinDate(currentDate.getTimeInMillis() - 1000);
datePickerDialog.show();
}
});
setTime = findViewById(R.id.setTime);
Calendar currentTime = Calendar.getInstance();
hour = currentTime.get(Calendar.HOUR_OF_DAY);
minute = currentTime.get(Calendar.MINUTE);
hour = selectedTimeFormat(hour);
setTime.setText(hour + " : " + minute + " " + format);
setTime.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
TimePickerDialog timePickerDialog = new TimePickerDialog(AddTaskActivity.this, new TimePickerDialog.OnTimeSetListener() {
@Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
hourOfDay = selectedTimeFormat(hourOfDay);
setTime.setText(hourOfDay + " : " + minute + " " + format);
}
}, hour, minute, false);
timePickerDialog.show();
}
});
}
public int selectedTimeFormat(int hour){
if (hour == 0){
format = "AM";
} else if (hour >= 12){
hour -= 12;
format = "PM";
} else {
format = "AM";
}
return hour;
}
public int codeToReturn(){
EditText editTextSummary = findViewById(R.id.summary);
summary = editTextSummary.getText().toString();
TextView textViewDate = findViewById(R.id.setDate);
date = textViewDate.getText().toString();
TextView textViewTime = findViewById(R.id.setTime);
time = textViewTime.getText().toString();
boolean check = isDateCorrect(date, time);
if (!check){
return 3;
}
if (TextUtils.isEmpty(summary.trim())) {
return 2;
} else return 1;
}
public boolean isDateCorrect (String date, String time){
String format = date + " " + time;
DateFormat df = new SimpleDateFormat("dd/MM/yyyy hh : mm a");
Date cal1 = new Date();
Date cal2 = null;
try {
cal2 = df.parse(format);
} catch (ParseException e) {
e.printStackTrace();
}
long diff = cal2.getTime() - cal1.getTime();
return (diff > 0);
}
public String getDeadline (String date, String time){
String format = date + " " + time;
DateFormat df = new SimpleDateFormat("dd/MM/yyyy hh : mm a");
Date cal1 = new Date();
Date cal2 = null;
try {
cal2 = df.parse(format);
} catch (ParseException e) {
e.printStackTrace();
}
long diff = cal2.getTime() - cal1.getTime();
long diffSeconds = diff/(1000);
long diffMinutes = diff / (60 * 1000);
long diffHours = diff / (60 * 60 * 1000);
long diffDays = diff / (24 * 60 * 60 * 1000);
if (diffDays>1 && diffHours > 24){
return String.valueOf(diffDays) + " days " + String.valueOf(diffHours - (diffDays*24)) + " hrs";
} else if (diffDays==1 && diffHours > 24) {
return String.valueOf(diffDays) + " day " + String.valueOf(diffHours - (diffDays*24)) + " hrs";
}else if (diffHours>=1){
return String.valueOf(diffHours) + " h";
} else if (diffSeconds > 0)
return String.valueOf(diffSeconds) + " s";
else return String.valueOf(diffMinutes) + " m";
}
public String getTags(List<String> tags){
String parsedTags = String.valueOf(tags).replace("[", "").replace("]", "");
return parsedTags;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_add_task, menu);
return true;
}
@Override
public void onBackPressed() {
Intent intent = new Intent();
super.setResult(Codes.INTENT_EMPTY_CODE, intent);
super.onBackPressed();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()){
case android.R.id.home:
finish();
return true;
case R.id.doneTask:
TagsEditText tagsEditText = findViewById(R.id.labels);
List<String> tags = tagsEditText.getTags();
Codes.INTENT_RESULT_CODE = codeToReturn();
if (Codes.INTENT_RESULT_CODE == 1){
String deadline = getDeadline(date, time);
String tagstostring = getTags(tags);
DbActivity db = new DbActivity(this);
boolean isInserted = db.insertData(summary, date, time, deadline, tagstostring, "list");
if (isInserted)
//
;
super.setResult(Codes.INTENT_RESULT_CODE);
finish();
} else if (Codes.INTENT_RESULT_CODE == 2) {
Toast.makeText(this, "You did not enter a summary", Toast.LENGTH_SHORT).show();
} else if (Codes.INTENT_RESULT_CODE == 3) {
Toast.makeText(this, "Invalid date", Toast.LENGTH_SHORT).show();
}
}
return super.onOptionsItemSelected(item);
}
}
希望得到任何帮助。
答案 0 :(得分：0)
这里可能错了，但如果您在数据库中没有数据运行.then(res => res.json())
，那么您正在设置
onCreate()但你永远不会打电话
recyclerView.setVisibility(View.GONE);
recyclerView.setVisibility(View.VISIBLE);
中，因此在重新启动应用程序之前，更新将不可见，并且在调用onActivityResult()时数据库中有一个项目。