我的#left {
margin: auto;
width: 30%;
padding: 10px;
float: left;
height: auto;
}
#middle {
margin: auto;
width: 30%;
padding: 10px;
height: auto;
}
#right {
margin: auto;
width: 30%;
padding: 10px;
float: right;
height: auto;
}
中有一个RecyclerView
。在每个RecyclerView行中,我有一个按钮,当按下它时,它应该打开一个带有RecyclerView列表的自定义片段对话框(这是一个多选对话框)。
在我的MainActivity.java
,这是我的另一个活动,我也有相同的按钮,应该做同样的事情(这就是为什么我需要模态作为片段对话框)。在我的SecondActivity.java
中,没有RecyclerView,它只是一个帖子(详细信息页面)。
我的问题:
当我点击SecondActivity.java
上的弹出按钮时,它会正常打开对话框片段弹出窗口。当我对RecyclerView中的任何一行(SecondActivity.java
)执行相同操作时,我收到MainActivity.java
错误:
ClassCastException
我的代码:
SecondActivity.java
java.lang.ClassCastException: com.example.appname.MainActivity cannot be cast to interfaces.DialogCommunicator$Communicator
PostsListAdapter.java
//*****************//
// THIS CODE WORKS //
//*****************//
// This code will run when the button is clicked.
// postOptions is a string array of menu items.
Bundle args = new Bundle();
args.putStringArray("displaymenu", postOptions);
mDialogFragment = new CustomDialogFragment();
mDialogFragment.setArguments(args);
mDialogFragment.show(getSupportFragmentManager(), "title");
CustomDialogFragment.java
//***************************//
// THIS CODE CRASHES THE APP //
//***************************//
// This code is planted in onClick method listener in onBindViewHolder
// for the button that's supposed to open the fragment dialog.
FragmentManager fm = ((MainActivity) mContext).getSupportFragmentManager();
String[] items = mContext.getResources().getStringArray(R.array.post_options);
CustomDialogFragment customDialogFragment = CustomDialogFragment.newInstance(items);
customDialogFragment.show(fm, "title");
MultiDialogAdapter.java
public class CustomDialogFragment extends DialogFragment {
private RecyclerView mRecyclerView;
public CustomDialogFragment() {
// Empty constructor is required for DialogFragment
// Make sure not to add arguments to the constructor
// Use `newInstance` instead as shown below
}
public static CustomDialogFragment newInstance(String[] items) {
CustomDialogFragment customDialogFragment = new CustomDialogFragment();
Bundle args = new Bundle();
args.putStringArray("displaymenu", items);
customDialogFragment.setArguments(args);
return customDialogFragment;
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.layout_multiselect_dialog, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Bundle args = getArguments();
String[] items = args.getStringArray("displaymenu");
List<String> itemsList = Arrays.asList(items);
// THIS LINE CRASHES ON POSTSLISTADAPTER!!!
MultiDialogAdapter adapter = new MultiDialogAdapter(getActivity(), itemsList);
mRecyclerView = (RecyclerView) view.findViewById(R.id.items_recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mRecyclerView.setAdapter(adapter);
getDialog().setTitle(null);
}
}
DialogCommunicator.java
public class MultiDialogAdapter extends RecyclerView.Adapter<MultiDialogViewHolder> {
private List<String> mItems;
private LayoutInflater mInflater;
private CustomFonts mCustomFont;
private DialogCommunicator.Communicator mCommunicator;
public MultiDialogAdapter(Context context, List<String> items) {
this.mInflater = LayoutInflater.from(context);
this.mItems = items;
this.mCustomFont = new CustomFonts(context);
try {
mCommunicator = (DialogCommunicator.Communicator) context;
} catch (ClassCastException e) {
// THIS IS WHERE THE CLASSCASTEXCEPTION HAPPENS!
throw new ClassCastException(context.toString());
}
}
@Override
public MultiDialogViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.layout_multiselect_dialog_row, parent, false);
return new MultiDialogViewHolder(view);
}
@Override
public void onBindViewHolder(MultiDialogViewHolder holder, int position) {
final String item = mItems.get(position);
holder.getItemTextView().setText(item);
holder.getItemTextView().setTypeface(mCustomFont.getPrimaryFontMedium());
holder.getItemTextView().setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCommunicator.onDialogButtonResponse(item);
}
});
}
@Override
public int getItemCount() {
return mItems.size();
}
}
class MultiDialogViewHolder extends RecyclerView.ViewHolder {
private TextView mItemTextView;
public MultiDialogViewHolder(View rootView) {
super(rootView);
mItemTextView = (TextView) rootView.findViewById(R.id.item_text_view);
}
public TextView getItemTextView() {
return mItemTextView;
}
}
崩溃日志:
public class DialogCommunicator {
public interface Communicator {
public void onDialogButtonResponse(String responseMessage);
}
}
我有10-06 14:35:12.353 21683-21683/com.example.appname E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.appname, PID: 21683
java.lang.ClassCastException: com.example.appname.MainActivity@e06db1e
at adapters.MultiDialogAdapter.<init>(MultiDialogAdapter.java:40)
at fragments.CustomDialogFragment.onViewCreated(CustomDialogFragment.java:60)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1430)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1740)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1809)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:799)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2580)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2367)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2322)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2229)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:700)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)
和PostsListAdapter.java
中实现的界面。这是一个回调方法,因此我可以响应每个单独的操作,并知道在片段对话框弹出窗口中单击了哪个项目。
因此,我已经正确构建了对话框片段,因为它在列表外部的常规活动中工作,但对于RecyclerView列表中的每一行,该对话框片段因SecondActivity.java
而崩溃了应用程序。为什么呢?
答案 0 :(得分:3)
您可以使用parent.getContext().
同样在onBindViewholder中,您忘记了对viewholder.Add进行类型转换
MultiDialogViewHolder viewholder=(MultiDialogViewHolder)holder;
然后访问viewholder.getItemTextView().setText(item);
在编译适配器中的上下文之前,对话框片段应该实现DialogCommunicator
。在对话框片段中添加DialogCommunicator
的实现
public class CustomDialogFragment extends DialogFragment implements DialogCommunicator {
//override the method
}
修改强>:
出现错误的主要问题还在于上下文。
这里传递MultiDialogAdapter adapter=new MultiDialogAdapter(getContext(), itemsList)
。
如果您将getActivity()传递给适配器,那么相应的活动必须实现接口DialogCommunicator
,并且回调将转到活动而不是CustomDialogFragment
。
所以传递getContext()
而不是getActivity()
,因为CustomDialogFragment正在实现接口而不是活动。
答案 1 :(得分:2)
你的崩溃是非常明确的:
MainActivity
无法投放到DialogCommunicator$Communicator
根据您发布的内容,您尚未在MainActivity
中实现此界面。你说:
我有
PostsListAdapter.java
和SecondActivity.java
实现的界面。
您有可能从implements DialogCommunicator.Communicator
移除PostsListAdapter
行,并将其添加到MainActivity
(当然也可以移动实际的实现)。
原因在于:
MultiDialogAdapter adapter = new MultiDialogAdapter(getActivity(), itemsList);
您将getActivity()
作为Context
参数传递给适配器的构造函数。这很好,除了对话框的构造函数然后将此Context
实例强制转换为您的接口。因此,可以显示此对话框的每个Activity
都必须实现您的界面。