android - Activity 和 Fragment 中可以实现的 DialogFragment 接口(interface)

Question

我有一个 ListFragment，它带有用于我的 ListItem 的上下文菜单。菜单选项之一用于删除项目，我想向用户显示一个确认对话框以防止意外删除。

public class MyListFragment extends ListFragment implements ConfirmDeletePopupFragment.DialogListener {

    (...)

    @Override
    public boolean onContextItemSelected(MenuItem item) {

        switch (item.getItemId()) {
            case R.id.action_delete:
                ConfirmDeletePopupFragment fragment = new ConfirmDeletePopupFragment();
                fragment.show(getSupportFragmentManager(), "tag");
                return true;
            case R.id.action_cancel:
                return true;
            default:
                return super.onContextItemSelected(item);
        }
    }

}

对于类似情况，我创建了一个通用确认对话框作为 DialogFragment，如下所示。我可以用它来让用户确认任何关键操作。为了在 Activity 中使用，它有一个带有 onDeleteConfirm 方法的接口(interface)，该方法处理创建对话框的 Activity 中的实际删除。

public class ConfirmDeletePopupFragment extends DialogFragment {

    (...)

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mDialogListener = (DialogListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(getTargetFragment().toString() + " must implement ConfirmDeletePopupFragment.DialogListener");
        }
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final android.app.AlertDialog.Builder dialogBuilder = new android.app.AlertDialog.Builder(getActivity());
        final LayoutInflater inflater = getActivity().getLayoutInflater();
        final View dialogView = inflater.inflate(R.layout.popup_confirm_delete, null);
        dialogBuilder.setView(dialogView);

        dialogBuilder.setTitle("Delete?");

        dialogBuilder.setNegativeButton(getString(R.string.activities_confirm_deletion_cancel_button), new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
            }
        });
        dialogBuilder.setPositiveButton(getString(R.string.activities_confirm_deletion_delete_button), new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                ((DialogListener) getActivity()).onDeleteConfirm();
            }
        });

        deleteDialog = dialogBuilder.create();
        deleteDialog.show();
        return deleteDialog;
    }

    public interface DialogListener {
        void onDeleteConfirm();
    }
}

显然，只有在 Activity (((DialogListener) getActivity()).onDeleteConfirm();) 中创建对话框时，此接口(interface)才有效。对于上述问题，我需要从 Listfragment 中创建对话框，而仅在 ListFragment 中实现对话框接口(interface)是行不通的(“Activity 必须实现 ConfirmDeletePopupFragment。对话监听器")

调整我的 DialogFragment 以适应这两种情况(在 Activity 或 Fragment 中创建)的最佳方式是什么？

Answer 1

显示对话框时( fragment ):

<dialog>.setTargetFragment(<your fragment>);
<dialog>.show();

在 Activity 中跳过 setTargetFragment。

在 DialogFragment 代码中:

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    if (getTargetFragment() != null) {
        myInterface = (YourCastInterface) getTargetFragment();
    } else {
        myInterface = (YourCastInterface) activity;
    }
}