onAttach(Activity) called once the fragment is associated with its activity.

在你的代码中

mListener = (SetupHotspotDialogListener) activity;

line抛出ClassCastException,因为您的活动未实现SetupHotspotDialogListener接口. (片段直接与包含它的活动相关联,以及DialogFragment,因为DialogFragment扩展了Fragment).

从docs开始

在某些情况下,您可能需要一个片段来与活动共享事件.一种好方法是在片段内定义一个回调接口,并要求主机活动实现它.当活动通过接口收到回调时,它可以根据需要与布局中的其他片段共享信息.

所以如果你想从Fragment创建FragmentDialog我建议通过回调来组织它到活动：

>使用createDialogRequest()等方法在SmartMode Fragment类中创建回调接口(就像在dialogFragment中一样).
>让您的活动实现该界面
>然后,当您需要创建对话框时,将回调从Fragment发送到Activity
>将“show dialog logics”放入Activity

它看起来像片段询问活动来创建对话框,活动显示对话框.

编辑：
我想我已经找到了更好的实现你需要的东西.我写了一个简单的例子,从片段创建片段对话框,接收片段对话框回调事件到片段.

活动：

public class MyFragmentActivity extends FragmentActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my_fragment);

    // first start of activity
    if (savedInstanceState == null) {
        // put fragment to activity layout 
        MyFragment fragment = new MyFragment();
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.fragmentContainer,fragment,"fragment");
        ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
        ft.commit();
    }
}}

分段：

public class MyFragment extends Fragment implements MyDialogInterface {

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

    View fragmentView = inflater.inflate(R.layout.fragment,null);

    // button which shows dialog
    Button showDialogButton = (Button) fragmentView.findViewById(R.id.showDialog);
    showDialogButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // create fragment dialog.
            FragmentDialog dialog = FragmentDialog.getInstance(MyFragment.this);
            dialog.show(getActivity().getSupportFragmentManager(),"dialog");
        }
    });
    return fragmentView;
}

@Override
public void onClickEvent() {
    // receive click events from dialog fragment
    Log.e(getClass().getSimpleName(),"onClickEvent");
}

}

FragmentDialog：

public class FragmentDialog extends DialogFragment {

public interface MyDialogInterface extends Serializable {
    public void onClickEvent();
}

private MyDialogInterface callbackListener;

/**
 * dialogInterface - instance of MyDialogInterface which will handle
 * callback events
 */
public static FragmentDialog getInstance(MyDialogInterface dialogInterface) {
    FragmentDialog fragmentDialog = new FragmentDialog();

    // set fragment arguments
    Bundle args = new Bundle();
    args.putSerializable("dialogInterface",dialogInterface);
    fragmentDialog.setArguments(args);

    return fragmentDialog;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setStyle(STYLE_NO_TITLE,0);
}

@Override
public View onCreateView(LayoutInflater inflater,Bundle savedInstanceState) {

    View pushDialogView = getActivity().getLayoutInflater().inflate(R.layout.fragment_dialog,null);

    // get reference to MyDialogInterface instance from arguments
    callbackListener = (MyDialogInterface) getArguments().getSerializable("dialogInterface");

    Button cancelButton = (Button) pushDialogView.findViewById(R.id.button);
    cancelButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // send click event
            callbackListener.onClickEvent();
        }
    });

    return pushDialogView;
}}

我使用了支持4个库片段(android.support.v4.app.Fragment,android.support.v4.app.DialogFragment,android.support.v4.app.FragmentActivity).

和布局：

activity_my_fragment.xml：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragmentContainer"
android:layout_width="match_parent"
android:layout_height="match_parent" />

fragment.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#a00"
android:orientation="vertical" >
<Button
    android:id="@+id/showDialog"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="show doalog" />
</LinearLayout>

fragment_dialog.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#fe3"
android:orientation="vertical" >

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="click me" />
 </LinearLayout>

我的想法是发送引用接口,它将捕获回调事件.