Question

我的课程扩展DialogFragment，如下所示：

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {

    EditText editDate;
    private Calendar dateTime = Calendar.getInstance();
    private SimpleDateFormat dateFormatter = new SimpleDateFormat("dd MMMM yyyy");

    public DatePickerFragment(EditText editText) {
        editDate = editText;
    }

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Use the current date as the default date in the picker
    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);

    // Create a new instance of DatePickerDialog and return it
    return new DatePickerDialog(getActivity(), this, year, month, day);

}

@Override
public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
        dateTime.set(year, monthOfYear, dayOfMonth);
        editDate.setText(dateFormatter
                .format(dateTime.getTime()));
    }

}

这就是我在Activity中使用它的方式：

public void showDatePickerDialog(View v) {
        new DatePickerFragment((EditText) v).show(getSupportFragmentManager(), "datePicker");
    }

并且这样打电话：

    <EditText
        android:id="@+id/editDate"
        android:onClick="showDatePickerDialog" />

但我总是得到：

Error: This fragment should provide a default constructor (a public constructor with no arguments)

Answer 1

较新版本的Android SDK会强制您获得一个空的无参数构造函数。这是一个很好的做法。这允许您将实例状态保存到bundle中，Android将重新创建调用默认构造函数的片段。

在这种情况下，您有以下解决方案：

首先，创建默认构造函数：

public DatePickerFragment() {}

创建实例并通过setter方法设置EditText：

DatePickerFragment fragment = new DatePickerFragment();
fragment.setEditText(v); // create this setter
fragment.show();

由于EditText是可分区的，您还可以设置为参数：

DatePickerFragment fragment = new DatePickerFragment();
Bundle bundle = new Bundle();
bundle.putExtra("EditText", v); 
fragment.setArguments(bundle); // setArguments is a method that already exists in fragments.
fragment.show(getSupportFragmentManager(), "DatePicker");

<强> [编辑] 如建议的那样，尝试忽略配置build.gradle的这些错误，如下所示：

lintOptions { 
  abortOnError false 
  checkReleaseBuilds false 
}

这不会通过在片段中使用非默认构造函数来停止构建应用程序。

Answer 2

您需要删除此构造函数

public DatePickerFragment(EditText editText) {
    editDate = editText;
}

您不应将视图引用传递给Fragment。如果要在Activity或其他地方更新EditText，请使用侦听器。

Answer 3

      public DatePickerFragment() {}

        @Override
        public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                dateTime.set(year, monthOfYear, dayOfMonth);
             //   editDate.setText(dateFormatter
             //         .format(dateTime.getTime()));
            Intent intent = new Intent();
            intent.setAction("CUSTOM_INTENT_FOR_SETTING_EDITTEXT");
            Bundle bundle = new Bundle();
            bundle.putString("my_data", dateTime.getTime.toString());
            intent.putExtras(bundle);
            sendBroadcast(intent);
            }




public class SubmitFragment extends Fragment {

    View view;
    EditText editDate;
    String strDate;
    Button btnSubmit;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment_submit, container, false);

        editDate = (EditText) view.findViewById(R.id.editDate);

        btnSend = (Button) view.findViewById(R.id.buttonSend);
        btnSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                strDate = editDate.getText().toString();
                Log.v("strDate..... >>>", strDate);

            }
        });

        return view;
    }


        // Our handler for received Intents. This will be called whenever an Intent
        // with an action named "CUSTOM_INTENT_FOR_SETTING_EDITTEXT" is broadcasted.
        private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
          @Override
          public void onReceive(Context context, Intent intent) {
            // Get extra data included in the Intent
            String message = intent.getStringExtra("my_data");
            Log.d("receiver", "message: " + message);
        *****// Use this message to set Edittext here...*****
          }
        };


        @Override
        protected void onPause() {
          // Unregister since the activity is about to be closed.
          LocalBroadcastManager.getInstance(getactivity()).unregisterReceiver(mMessageReceiver);
          super.onDestroy();
        }


        @Override
        protected void onResume() {
          // register the receiver here..
       super.onResume(); LocalBroadcastManager.getInstance(getactivity()).registerReceiver(mMessageReceiver,
              new IntentFilter("CUSTOM_INTENT_FOR_SETTING_EDITTEXT"));
        }
}

希望这会有所帮助..我在这里做的正是使用localBroadcast来做必要的。另一种方法是使用settext的接口但是关于这种方法的一个错误的事情是当应用程序处于后台时 long，当再次调用oncreateview时它将返回null。

Answer 4

添加@SuppressLint（“ValidFragment”）

在你上课之前，

公共类DatePickerFragment extends

我希望它可以帮到你

错误：此片段应提供默认构造函数（不带参数的公共构造函数）

4 个答案: