如何将数据从DialogFragment发送到片段？

Question

我有一个片段打开一个Dialogfragment获取用户输入(一个字符串,和一个整数).如何将这两件事发回片段？

这是我的DialogFragment:

public class DatePickerFragment extends DialogFragment {
    String Month;
    int Year;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        getDialog().setTitle(getString(R.string.Date_Picker));
        View v = inflater.inflate(R.layout.date_picker_dialog, container, false);

        Spinner months = (Spinner) v.findViewById(R.id.months_spinner);
        ArrayAdapter<CharSequence> monthadapter = ArrayAdapter.createFromResource(getActivity(),
                R.array.Months, R.layout.picker_row);
              months.setAdapter(monthadapter);
              months.setOnItemSelectedListener(new OnItemSelectedListener(){
                  @Override
                  public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int monthplace, long id) {
                      Month = Integer.toString(monthplace);
                  }
                  public void onNothingSelected(AdapterView<?> parent) {
                    }
              });

        Spinner years = (Spinner) v.findViewById(R.id.years_spinner);
        ArrayAdapter<CharSequence> yearadapter = ArrayAdapter.createFromResource(getActivity(),
             R.array.Years, R.layout.picker_row);
        years.setAdapter(yearadapter);
        years.setOnItemSelectedListener(new OnItemSelectedListener(){
          @Override
          public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int yearplace, long id) {
              if (yearplace == 0){
                  Year = 2012;
              }if (yearplace == 1){
                  Year = 2013;
              }if (yearplace == 2){
                  Year = 2014;
              }
          }
          public void onNothingSelected(AdapterView<?> parent) {}
        });

        Button button = (Button) v.findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
           public void onClick(View v) {
               getDialog().dismiss();
            }
        });

        return v;
    }
}

我需要在点击按钮之后发送数据 getDialog().dismiss()

以下是需要将数据发送到的片段:

public class CalendarFragment extends Fragment {
int Year;
String Month;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    int position = getArguments().getInt("position");
    String[] categories = getResources().getStringArray(R.array.categories);
    getActivity().getActionBar().setTitle(categories[position]);
    View v = inflater.inflate(R.layout.calendar_fragment_layout, container, false);    

    final Calendar c = Calendar.getInstance();
    SimpleDateFormat month_date = new SimpleDateFormat("MMMMMMMMM");
    Month = month_date.format(c.getTime());
    Year = c.get(Calendar.YEAR);

    Button button = (Button) v.findViewById(R.id.button);
    button.setText(Month + " "+ Year);
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
           new DatePickerFragment().show(getFragmentManager(), "MyProgressDialog");
        }
    });
   return v;
  }
}

因此,一旦用户选择了日期Dialogfragment,它必须返回月份和年份.

然后,按钮上的文本应更改为用户指定的月份和年份.

Answer 1

注意:除了一个或两个Android Fragment特定调用之外,这是用于在松散耦合的组件之间实现数据交换的通用方法配方.您可以安全地使用此方法在字面上交换数据,无论是片段,活动,对话还是应用程序的任何其他元素.

这是食谱:

1. 创建interface(即命名MyContract)包含传递数据的方法的签名,即methodToPassData(... data);.
2. 确保您的DialogFragmentfullfils合同(通常意味着实现所需的接口):class MyFragment extends Fragment implements MyContract {....}
3. 在创建时通过调用DialogFragment将您的调用设置Fragment为其目标片段myDialogFragment.setTargetFragment(this, 0);.这是您稍后将要讨论的对象.
4. 在您的中DialogFragment,通过调用getTargetFragment();并将返回的对象强制转换为您在步骤1中创建的契约接口来获取该调用片段,方法是:MyContract mHost = (MyContract)getTargetFragment();.Casting让我们确保目标对象实现所需的合同,我们可以期待methodToPassData()在那里.如果没有,那么你会定期ClassCastException.这通常不应该发生,除非你做了太多的复制粘贴编码:)如果你的项目使用外部代码,库或插件等,在这种情况下你应该捕获异常并告诉用户即插件不兼容而不是让app崩溃.
5. 当发回数据的时间到来时,请调用methodToPassData()您之前获得的对象:((MyContract)getTargetFragment()).methodToPassData(data);.如果你onAttach()已经将目标片段转换并分配给类变量(即mHost),那么这段代码就是这样mHost.methodToPassData(data);.
6. 瞧.

您刚刚将对话框中的数据成功传递回调用片段.

Answer 2

这是另一个没有使用任何接口的配方.只需使用setTargetFragment和Bundle在DialogFragment和Fragment之间传递数据.

public static final int DATEPICKER_FRAGMENT = 1; // class variable

1.拨打DialogFragment如下所示:

// create dialog fragment
DatePickerFragment dialog = new DatePickerFragment();

// optionally pass arguments to the dialog fragment
Bundle args = new Bundle();
args.putString("pickerStyle", "fancy");
dialog.setArguments(args);

// setup link back to use and display
dialog.setTargetFragment(this, DATEPICKER_FRAGMENT);
dialog.show(getFragmentManager().beginTransaction(), "MyProgressDialog")

2.使用额外Bundle的一个Intent在DialogFragment传递什么信息回目标片段.下面的代码中Button#onClick()的事件DatePickerFragment传递一个字符串和整数.

Intent i = new Intent()
        .putExtra("month", getMonthString())
        .putExtra("year", getYearInt());
getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, i);
dismiss();

3.使用CalendarFragment的onActivityResult()方法来读取值:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) {
        case DATEPICKER_FRAGMENT:
            if (resultCode == Activity.RESULT_OK) {
                Bundle bundle = data.getExtras();
                String mMonth = bundle.getString("month", Month);
                int mYear = bundle.getInt("year");
                Log.i("PICKER", "Got year=" + year + " and month=" + month + ", yay!");
            } else if (resultCode == Activity.RESULT_CANCELED) {
                ...
            }
            break;
    }
}

Answer 3

一个好的技巧是使用ViewModel和LiveData方法，这是最好的方法。下面是关于如何在Fragments 之间共享数据的代码示例：

class SharedViewModel : ViewModel() {
    val selected = MutableLiveData<Item>()

    fun select(item: Item) {
        selected.value = item
    }
}

class MasterFragment : Fragment() {

    private lateinit var itemSelector: Selector

    private lateinit var model: SharedViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        model = activity?.run {
            ViewModelProviders.of(this).get(SharedViewModel::class.java)
        } ?: throw Exception("Invalid Activity")
        itemSelector.setOnClickListener { item ->
            // Update the UI
        }
    }
}

class DetailFragment : Fragment() {

    private lateinit var model: SharedViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        model = activity?.run {
            ViewModelProviders.of(this).get(SharedViewModel::class.java)
        } ?: throw Exception("Invalid Activity")
        model.selected.observe(this, Observer<Item> { item ->
            // Update the UI
        })
    }
}

尝试一下，这些新组件来帮助我们，我认为它比其他方法更有效。

了解更多相关信息：https ://developer.android.com/topic/libraries/architecture/viewmodel

Answer 4

这是一种说明 Marcin 在 kotlin 中实现的答案的方法。

1.创建一个接口，该接口具有在 dialogFragment 类中传递数据的方法。

interface OnCurrencySelected{
    fun selectedCurrency(currency: Currency)
}

2.在你的 dialogFragment 构造函数中添加你的界面。

class CurrencyDialogFragment(val onCurrencySelected :OnCurrencySelected)    :DialogFragment() {}

3.现在让你的Fragment实现你刚刚创建的接口

class MyFragment : Fragment(), CurrencyDialogFragment.OnCurrencySelected {

override fun selectedCurrency(currency: Currency) {
//this method is called when you pass data back to the fragment
}}

4.然后显示你的dialogFragment你刚刚调用 CurrencyDialogFragment(this).show(fragmentManager,"dialog")。this是您将与之交谈的接口对象，用于将数据传递回您的 Fragment。

5.当您想将数据发送回您的 Fragment 时，您只需调用该方法以在您在 dialogFragment 构造函数中传递的接口对象上传递数据。

onCurrencySelected.selectedCurrency(Currency.USD)
dialog.dismiss()