我有以下代码在Activity中显示日期选择器，但是当我尝试将我的活动转换为Fragment时，我收到错误。我无法真正看到代码与SO中的解决方案相比在Fragment中实现DialogFragment的任何差异。
你能指出我错过了什么吗？
MainFragment：
public class AddEntryFragment extends Fragment implements DatePickerFragment.TheListener{
EditText datpurchased;
public AddEntryFragment(){}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_addentry, container, false);
return rootView;
}
@Override
public void onStart() {
super.onStart();
datpurchased = (EditText) getView().findViewById(R.id.datepurchased);
datpurchased.setOnClickListener(onClickListener);
}
private OnClickListener onClickListener = new OnClickListener() {
@Override
public void onClick(View v) {
switch(v.getId()){
case R.id.datepurchased:
showdate(v);
break;
default:
break;
}
}
};
public void showdate(View v) {
DialogFragment newFragment = new DatePickerFragment();
Bundle bundle = new Bundle();
bundle.putString("dateAsText",datpurchased.getText().toString());
newFragment.setArguments(bundle);
newFragment.show(getFragmentManager(), "datePicker");
}
public void returnDate(String date) {
datpurchased.setText(date);
}
}
DatePickerFragment：
public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {
TheListener listener;
public interface TheListener{
public void returnDate(String date);
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState){
Bundle bundle = getArguments();
String date = bundle.getString("dateAsText");
int year, month, day;
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd",Locale.US);
df.setLenient(false);
Date d = null;
Calendar c=Calendar.getInstance();
try {
d = df.parse(date);
c.setTime(d);
} catch (ParseException e) {
//e.printStackTrace();
}
year=c.get(Calendar.YEAR);
month=c.get(Calendar.MONTH);
day=c.get(Calendar.DAY_OF_MONTH);
listener = (TheListener) getActivity();
return new DatePickerDialog(getActivity(), this, year, month, day);
}
public void onDateSet(DatePicker view, int year, int month, int day){
Calendar c = Calendar.getInstance();
c.set(year, month, day);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd",Locale.US);
String formattedDate = sdf.format(c.getTime());
if (listener != null)
{
listener.returnDate(formattedDate);
}
}
}
logcat的：
12-18 23:35:41.094: D/AndroidRuntime(1058): Shutting down VM
12-18 23:35:41.094: W/dalvikvm(1058): threadid=1: thread exiting with uncaught exception (group=0xb4a65b90)
12-18 23:35:41.124: E/AndroidRuntime(1058): FATAL EXCEPTION: main
12-18 23:35:41.124: E/AndroidRuntime(1058): Process: com.migrationdesk.mylibman, PID: 1058
12-18 23:35:41.124: E/AndroidRuntime(1058): java.lang.ClassCastException: com.migrationdesk.mylibman.NavContainer cannot be cast to com.migrationdesk.mylibman.DatePickerFragment$TheListener
12-18 23:35:41.124: E/AndroidRuntime(1058): at com.migrationdesk.mylibman.DatePickerFragment.onCreateDialog(DatePickerFragment.java:41)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.DialogFragment.getLayoutInflater(DialogFragment.java:398)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.BackStackRecord.run(BackStackRecord.java:684)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.os.Handler.handleCallback(Handler.java:733)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.os.Handler.dispatchMessage(Handler.java:95)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.os.Looper.loop(Looper.java:137)
12-18 23:35:41.124: E/AndroidRuntime(1058): at android.app.ActivityThread.main(ActivityThread.java:4998)
12-18 23:35:41.124: E/AndroidRuntime(1058): at java.lang.reflect.Method.invokeNative(Native Method)
12-18 23:35:41.124: E/AndroidRuntime(1058): at java.lang.reflect.Method.invoke(Method.java:515)
12-18 23:35:41.124: E/AndroidRuntime(1058): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-18 23:35:41.124: E/AndroidRuntime(1058): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-18 23:35:41.124: E/AndroidRuntime(1058): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：25)
试试这个示例代码......
public class student extends Fragment {
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.layout_main, container, false);
return view;
}
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
edittext.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
showDatePicker();
}
});
}
private void showDatePicker() {
DatePickerFragment date = new DatePickerFragment();
/**
* Set Up Current Date Into dialog
*/
Calendar calender = Calendar.getInstance();
Bundle args = new Bundle();
args.putInt("year", calender.get(Calendar.YEAR));
args.putInt("month", calender.get(Calendar.MONTH));
args.putInt("day", calender.get(Calendar.DAY_OF_MONTH));
date.setArguments(args);
/**
* Set Call back to capture selected date
*/
date.setCallBack(ondate);
date.show(getFragmentManager(), "Date Picker");
}
OnDateSetListener ondate = new OnDateSetListener() {
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
edittext.setText(String.valueOf(dayOfMonth) + "-" + String.valueOf(monthOfYear+1)
+ "-" + String.valueOf(year));
}
};
}
创建另一个类DatePickerFragment。
public class DatePickerFragment extends DialogFragment {
OnDateSetListener ondateSet;
private int year, month, day;
public DatePickerFragment() {}
public void setCallBack(OnDateSetListener ondate) {
ondateSet = ondate;
}
@SuppressLint("NewApi")
@Override
public void setArguments(Bundle args) {
super.setArguments(args);
year = args.getInt("year");
month = args.getInt("month");
day = args.getInt("day");
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return new DatePickerDialog(getActivity(), ondateSet, year, month, day);
}
}
答案 1 :(得分：1)
import android.app.Activity;
import android.app.FragmentManager;
import android.content.Context;
import android.content.DialogInterface;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.graphics.drawable.GradientDrawable;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.nepal.peace.ilovemydiet.R;
import com.wdullaer.materialdatetimepicker.Utils;
import com.wdullaer.materialdatetimepicker.date.DatePickerDialog;
import java.util.Calendar;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link UserPhysicalCharacter.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link UserPhysicalCharacter#newInstance} factory method to
* create an instance of this fragment.
*/
public class UserPhysicalCharacter extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
EditText f_name, l_name, u_height, u_weight, u_obj_weight;
TextView u_birth;
SharedPreferences sharedpreferences;
public static final String MyPREFERENCES = "LoginData";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment UserPhysicalCharacter.
*/
// TODO: Rename and change types and number of parameters
public static UserPhysicalCharacter newInstance(String param1, String param2) {
UserPhysicalCharacter fragment = new UserPhysicalCharacter();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
public UserPhysicalCharacter() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_relpace, container, false);
final UserPhysicalCharacter userPhysicalCharacter=new UserPhysicalCharacter();
Toolbar toolbar = (Toolbar) rootView.findViewById(R.id.toolbar);
u_birth = (TextView) rootView.findViewById(R.id.birthday);
u_birth.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Calendar now = Calendar.getInstance();
DatePickerDialog dpd = DatePickerDialog.newInstance(
new DateListener(),
now.get(Calendar.YEAR),
now.get(Calendar.MONTH),
now.get(Calendar.DAY_OF_MONTH)
);
dpd.setThemeDark(true);
dpd.vibrate(true);
dpd.dismissOnPause(true);
dpd.setAccentColor(Color.parseColor("#9C27B0"));
dpd.setTitle("DatePicker Title");
dpd.show(getActivity().getFragmentManager(),"Datepickerdialog");
}
});
return rootView;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
public class DateListener implements DatePickerDialog.OnDateSetListener {
@Override
public void onDateSet(DatePickerDialog view, int year, int monthOfYear, int dayOfMonth) {
String date = dayOfMonth+"/"+(++monthOfYear)+"/"+year;
Toast.makeText(getActivity(),date, Toast.LENGTH_SHORT).show();
u_birth.setText(date);
}
}
}
答案 2 :(得分：1)
我得到了完全相同的投射错误，在寻找解决方案后，但没有找到一个运行良好的解决方案，我决定想出一个我自己的。
我的方法是使用一个小技巧。我没有试图让扩展DialogFragment的类接受我的Fragment作为DatePickerDialog.OnDateSetListener，而是允许DialogFragment类实现接口并接收回调。当调用回调时，它会将它传递给我的Fragment，它也实现了相同的接口。实际上，DialogFragment类转发回调。这是DialogFragment类，您可能在许多其他stackoverflow帖子中看到过，除了它有一个公共方法setListeningActivity（）。 setListeningActivity（）接受一个片段，一个活动，或者实际上任何实现DatePickerDialog.OnDateSetListener的类。这是转发DialogFragment类的任何回调的类。
public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {
private DatePickerDialog.OnDateSetListener m_listener = null;
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int day = c.get(Calendar.DAY_OF_MONTH);
return new DatePickerDialog(getActivity(),
this,
year, month, day);
}
public void setListeningActivity(DatePickerDialog.OnDateSetListener listener)
{
m_listener = listener;
}
@Override
public void onDateSet(DatePicker view, int year, int month, int day) {
if (m_listener != null) {
m_listener.onDateSet(view, year, month, day);
}
}
接下来是使用它的代码：
public class AppPatientInfoFragment extends Fragment implements DatePickerDialog.OnDateSetListener {
...
private void setDate(final Calendar calendar) {
final DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.MEDIUM);
((TextView) m_activity.findViewById(R.id.dob)).setText(dateFormat.format(calendar.getTime()));
}
public void onDateSet(DatePicker view, int year, int month, int day) {
Calendar c = Calendar.getInstance();
c.set(year, month, day);
setDate(c);
}
...
DatePickerFragment fragment = new DatePickerFragment();
fragment.setListeningActivity(AppPatientInfoFragment.this);
fragment.show(m_activity.getFragmentManager(), "date");
基本上，发生的事情是DatePickerFragment的onDateSet（）被调用，因为它是用DatePicker注册的实际回调，然后DatePickerFragment的onDateSet（）会将它转发给AppPatientInfoFragment的onDateSet （）。
答案 3 :(得分：0)
我使用了一个实现Date Listeners的AppCompatActivity。碎片是必要的，因为我需要编写日期范围选择器。
对于容器活动，这是类声明：
public class AppCompatDateRange extends AppCompatActivity implements
DateIniRangeFragment.OnDateIniSelectedListener, DateFimRangeFragment.OnDateFimSelectedListener
回调的接口：
@Override
public void onDateIniSelected(String dataIni) {
Log.i("data inicial:", dataIni);
}
@Override
public void onDateFimSelected(String dataFim) {
Log.i("data final:", dataFim);
}
回调是字符串，因为日期是查询选择中的参数。
片段的代码（基于初始日期片段）：
public class DateIniRangeFragment extends Fragment {
OnDateIniSelectedListener callbackIni;
private DatePicker startDatePicker;
public DateIniRangeFragment() {
///required empty constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
///through this interface the fragment sends data to the container activity
public interface OnDateIniSelectedListener {
void onDateIniSelected(String dataIni);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
///layout for the fragment
View v = inflater.inflate(R.layout.date_ini_fragment, container, false);
///initial date for the picker, in this case, current date
startDatePicker = (DatePicker) v.findViewById(R.id.start_date_picker_appcompat);
Calendar c = Calendar.getInstance();
int ano = c.get(Calendar.YEAR);
int mes = c.get(Calendar.MONTH);
int dia = c.get(Calendar.DAY_OF_MONTH);
startDatePicker.setSpinnersShown(false);
startDatePicker.init(ano, mes, dia, dateSetListener);
return v;
}
///listener that receives the selected date
private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() {
public void onDateChanged(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
if (view.isShown()) { ///if the datepicker is on the screen
String sDataIni = year + "-" + (monthOfYear + 1) + "-" + dayOfMonth;
callbackIni.onDateIniSelected(sDataIni); //apply date to callback, string format
}
}
};
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
/*
* this function guarantees that the container activity implemented the callback interface
* */
try {
callbackIni = (OnDateIniSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString() + " deve implementar OnDateIniSelectedListener");
}
}
}
为了组合容器+片段，我使用ViewPager（AppCompat）和一个扩展FragmentPagerAdapter的自定义类。没有对话框。