DatePicker更改日期後挑選視圖

Question

我有一個按鈕，它拉起DatePicker片段，但我不知道如何使視圖更改取決於所選日期。我把onDateSet方法放在我的main.java中，這是調用片段的活動，意圖在這個方法內部改變視圖，但是當日期改變時它什麼都不做，我不知道我做錯了什麼。

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener { 

    @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); 
    } 

    public void onDateSet(DatePicker view, int year, int monthOfYear, 
      int dayOfMonth) { 
     // TODO Auto-generated method stub 
    } 

和我MainScreen.java是

public class MainScreen extends FragmentActivity implements DatePickerDialog.OnDateSetListener { 

    static final int DATE_DIALOG_ID = 0; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main_screen); 
    } 

    public void showDatePickerDialog(View v) { 
     DatePickerFragment newFragment = new DatePickerFragment(); 
     newFragment.show(getFragmentManager(), "datePicker"); 
    } 

    public void onDateSet(DatePicker view, int year, int monthOfYear, 
      int dayOfMonth) { 

     Intent intent = new Intent(this, January_1.class); 
     startActivity(intent); 
    } 
} 

Answer 1

你應該在你DatePickerFragement使用onDateSet()聽衆：

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener { 

    @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); 
    } 

    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) { 
     Activity activity = getActivity(); 
     Intent intent = new Intent(activity, January_1.class); 
     activity.startActivity(intent); 
    } 
} 

---

新增自評

您使用了錯誤的指數爲monthOfYear，從the documentation：

monthOfYear所設的月份（0-11）與Calendar兼容性。

因此一月份爲0，二月是1，等...
爲了限制任何混亂，我建議使用來自Calendar類月份名稱和switch語句：

Intent intent; 
switch(monthOfYear) { 
case Calendar.JANUARY: 
    intent = new Intent(activity, January_1.class); 
    break; 
case Calendar.FEBRUARY: 
    // etc... 
} 
activity.startActivity(intent);