How to correctly set the minimum date?

Question

Java

I have two buttons. First departure, second arrival. Departure date has minDate = today. And the date of arrival minDate must be equal to the selected date for departure.
In onCreate():

final Calendar nextYear = Calendar.getInstance();
        nextYear.add(Calendar.YEAR, 1);

        Date today = new Date();
        Date departs;

        initButtonListeners(today, nextYear);

The clicks themselves:

public void initButtonListeners(final Date today, final Calendar nextYear) {
        findViewById(id.linearCalendar).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showCalendarInDialog("Выберите дату вылета", R.layout.calendar_dialog_customized);

                    dialogView.init(today, nextYear.getTime())
                            .withSelectedDate(new Date(departData));

            }
        });

        findViewById(id.linearArrive).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showCalendarInDialog("Выберите дату прилета", R.layout.calendar_dialog_customized);

                Date dates = null;

                    SimpleDateFormat format = new SimpleDateFormat("dd MMM yyyy");
                    try {
                        dates = format.parse(departData);
                    } catch (ParseException e) {
                        e.printStackTrace();
                    }
                    dialogView.init(dates, nextYear.getTime())
                            .withSelectedDate(new Date(arriveData));
                }

            }
        });

    }

OnDateClickListener:

dialogView.setOnDateSelectedListener(new CalendarPickerView.OnDateSelectedListener() {

            DateFormat dateFormat = new SimpleDateFormat("dd MMM yyyy");
            

            @Override
            public void onDateSelected(Date date) {
                if(isFrom){

                    departData = dateFormat.format(date);

                    tvDepart.setText(departData);
                  
                }else{

                    arriveData = dateFormat.format(date);

                    tvArrive.setText(arriveData);
                  
                }

                theDialog.dismiss();

            }

            @Override
            public void onDateUnselected(Date date) {

            }

        });

When you click Arrival, the application crashes, says zero value
Error:

java.lang.IllegalArgumentException: The string argument is null
     at java.util.Date.parse(Date.java:373)
     at java.util.Date.<init>(Date.java:149)
     at com.tezz.MainContent.ContentActivity$2.onClick(ContentActivity.java:305)
     at android.view.View.performClick(View.java:4084)
     at android.view.View$PerformClick.run(View.java:16966)
     at android.os.Handler.handleCallback(Handler.java:615)
     at android.os.Handler.dispatchMessage(Handler.java:92)
     at android.os.Looper.loop(Looper.java:137)
     at android.app.ActivityThread.main(ActivityThread.java:4745)
     at java.lang.reflect.Method.invokeNative(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:511)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
     at dalvik.system.NativeStart.main(Native Method)

Question:
What is wrong, how to set minDate?