如何返回对话片段结果值答案

【问题标题】：How to return Dialogue fragments result values如何返回对话片段结果值
【发布时间】：2016-06-10 12:51:52
【问题描述】：

我创建了一个DateandTimePickerDialogueFragment，我正在从MainActivity 调用DateandTimePickerDialogueFragment。

我的问题是，如何将DateandTimePickerDialogueFragment 结果值发送到MainActivity。

MainActivity：

@Override
public void onClick(View v) {

    if (v.getId() == R.id.buttonid) {

        DateandTimePickerDialogueFragment dateandTimePickerDialogueFragment = new DateandTimePickerDialogueFragment();
        dateandTimePickerDialogueFragment.show(getSupportFragmentManager(), "DateandTimePickerDialogueFragment");
    }
}

DateandTimePickerDialogueFragment：

public class DateandTimePickerDialogueFragment extends DialogFragment {

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

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        return displayDateDialogPicker(getActivity());
    }

    /**
     * @param context
     */
    private Dialog displayDateDialogPicker(Context context) {

        int mYear, mMonth, mDay;
        final Calendar c = Calendar.getInstance();
        mYear = c.get(Calendar.YEAR);
        mMonth = c.get(Calendar.MONTH);
        mDay = c.get(Calendar.DAY_OF_MONTH);

        DatePickerDialog dpd = new DatePickerDialog(context,
                new DatePickerDialog.OnDateSetListener() {

                    @Override
                    public void onDateSet(DatePicker view, int year,
                                          int monthOfYear, int dayOfMonth) {
                        int mymonth = monthOfYear + 1;
                        String mmmMonth = "", mmDate = "";
                        if (mymonth > 0 && mymonth < 10) {

                            mmmMonth = "0" + mymonth;

                        } else {

                            mmmMonth = "" + mymonth;
                        }

                        if (dayOfMonth > 0 && dayOfMonth < 10) {
                            mmDate = "0" + dayOfMonth;
                        } else {

                            mmDate = "" + dayOfMonth;
                        }
                        //YYYY-MM-DD
                        String finalDate = year + "-" + (mmmMonth) + "-" + mmDate;

                        Intent intentData = new Intent();
                        intentData.putExtra("Date", finalDate);

                        getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, intentData);
                    }
                }, mYear, mMonth, mDay);
        dpd.show();
        return dpd;
    }
}

【问题讨论】：

你能写一个方法来更新你的类变量以获得结果吗？

标签： android android-dialogfragment android-datepicker datepickerdialog

【解决方案1】：

虽然不在 DialogFragment 上使用包含方法或 valueType 的接口，但在返回 dpd 之前，将该 dpd 插入该变量接口并在 MainActivity 上实现该接口。

【讨论】：

【解决方案2】：

在您的DialogFragment 中，您可以为此制作接口

用下面的代码替换完整的代码

public class DateandTimePickerDialogueFragment extends DialogFragment {
public static interface OnCompleteListener {
    public abstract void onComplete(String time);
}

private OnCompleteListener mListener;
// make sure the Activity implemented it

public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        this.mListener = (OnCompleteListener) activity;
    } catch (final ClassCastException e) {
        throw new ClassCastException(activity.toString() + " must implement OnCompleteListener");
    }
}

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

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    return displayDateDialogPicker(getActivity());
}

/**
 * @param context
 */
private Dialog displayDateDialogPicker(Context context) {
    mListener = (OnCompleteListener)getActivity();
    int mYear, mMonth, mDay;
    final Calendar c = Calendar.getInstance();
    mYear = c.get(Calendar.YEAR);
    mMonth = c.get(Calendar.MONTH);
    mDay = c.get(Calendar.DAY_OF_MONTH);

    DatePickerDialog dpd = new DatePickerDialog(context,
            new DatePickerDialog.OnDateSetListener() {

                @Override
                public void onDateSet(DatePicker view, int year,
                                      int monthOfYear, int dayOfMonth) {
                    int mymonth = monthOfYear + 1;
                    String mmmMonth = "", mmDate = "";
                    if (mymonth > 0 && mymonth < 10) {

                        mmmMonth = "0" + mymonth;

                    } else {

                        mmmMonth = "" + mymonth;
                    }

                    if (dayOfMonth > 0 && dayOfMonth < 10) {
                        mmDate = "0" + dayOfMonth;
                    } else {

                        mmDate = "" + dayOfMonth;
                    }
                    //YYYY-MM-DD
                    String finalDate = year + "-" + (mmmMonth) + "-" + mmDate;


                    mListener.onComplete(finalDate);
                   // getTargetFragment().onActivityResult(getTargetRequestCode(), Activity.RESULT_OK, intentData);
                }
            }, mYear, mMonth, mDay);
    dpd.show();
    return dpd;
}
}

现在您可以在您的活动中implements DateandTimePickerDialogueFragment.OnCompleteListener 并导入接口的方法，在此方法中您可以获取您的数据

 @Override
public void onComplete(String time) {
    Log.d("TAG", time.toString());
}

【讨论】：

我得到了类似 java.lang.NullPointerException 的异常：尝试调用虚拟方法 'void android.support.v4.app.Fragment.onActivityResult(int, int, android.content.Intent)' on空对象引用
尝试先检查Intent是否为空

【解决方案3】：

你会想要设置一个接口监听器。

在您的对话框片段中：

    public interface DateandTimeListener {
         public void OnDateTimeSelected(String date);
    }

    private static DateandTimeListener mListener;

    //Your activity will call this. Passing its context 'this' as the listener.
    public void setDateandTimeListener(DateandTimeListener listener){
         mListener = listener;
    }

然后在你的 onDateSet 中：

 public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth){
 ....                        
 String finalDate = year + "-" + (mmmMonth) + "-" + mmDate;
 mListener.OnDateTimeSelected(finalDate);

 ....
 }

在您的 MainActivity 中：

确保你实现了监听器。

 public class MainActivity extends Activity implements DateandTimePickerDialogueFragment.DateandTimeListener

这将强制您覆盖活动中的OnDateTimeSelected 回调函数。从那里您将获得从对话框返回的 finalDate 字符串。

另外在你的活动中确保你调用setDateandTimeListener(this)来设置监听器

希望有帮助！

【讨论】：