Question

我在recyclerView中放置了fragment，但似乎看不出错误在哪里。我尝试了许多修复程序，但该应用程序始终崩溃。

有人可以帮助我让recyclerView显示在fragment上吗？

我的Java文件代码

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    ((MainActivity) getActivity()).setTitle("VIEW ALL MODULES");
    recyclerView = (RecyclerView) getActivity().findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    moduleList = new ArrayList<>();
    Module m1 = new Module(1, 1, 2, 3, 4, "ONT4101", "DEV SOFT", "NMU", "ITC", "Haskins");
    Module m2 = new Module(2, 1, 5, 37, 44, "AIN4002", "AI", "NMU", "ITC", "THUG LIFE");
    Module m3 = new Module(3, 2, 2, 13, 44, "ONT4300", "PROJECT", "NMU", "ITC", "Haskins");
    moduleList.add(m1);
    moduleList.add(m2);
    moduleList.add(m3);
    moduleAdapter = new ModuleAdapter(getActivity(), moduleList);
    recyclerView.setAdapter(moduleAdapter);
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_view_all_module, container, false);
}

XML文件

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

<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />

</LinearLayout>

适配器类

 public class ModuleAdapter extends RecyclerView.Adapter<ModuleAdapter.ModuleViewHolder>{
    private Context mCtx;
    private List<Module> moduleList;
    public ModuleAdapter(Context mCtx, List<Module> moduleList) {
        this.mCtx = mCtx;
        this.moduleList = moduleList;
    }
    @NonNull
    @Override
    public ModuleViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(mCtx);

        View view = inflater.from(parent.getContext())
                .inflate(R.layout.module_list, parent, false);
        return new ModuleViewHolder(view);
    }
    @Override
    public void onBindViewHolder(@NonNull ModuleViewHolder holder, int position) {
        Module module = moduleList.get(position);
        holder.textModCodeView.setText(module.getModcode());
        holder.textModuleDescView.setText(module.getModdesc());
        holder.textEducatorView.setText("Educator: "+ module.getEducator());
        holder.textNoOfTestView.setText("Tests: "+ String.valueOf(module.getNooftest()));
        holder.textNoOfAssView.setText("Assignments: "+ String.valueOf(module.getNoofass()));
        holder.textNoOfPracView.setText("Practicals: "+ String.valueOf(module.getNoofprac()));
        holder.textNoOfExamView.setText("Exams: "+ String.valueOf(module.getNoofexam()));

        Random r = new Random();
        int red=r.nextInt(255 - 0 + 1)+0;
        int green=r.nextInt(255 - 0 + 1)+0;
        int blue=r.nextInt(255 - 0 + 1)+0;

        GradientDrawable draw = new GradientDrawable();
        draw.setShape(GradientDrawable.RECTANGLE);
        draw.setColor(Color.rgb(red,green,blue));
        holder.textModCodeView.setBackground(draw);
    }
    @Override
    public int getItemCount() {
        return moduleList.size();
    }

    class ModuleViewHolder extends RecyclerView.ViewHolder{

        TextView textModCodeView,textModuleDescView,textEducatorView,textNoOfTestView,textNoOfAssView,textNoOfPracView,textNoOfExamView;
        public ModuleViewHolder(View itemView) {
            super(itemView);

            textModCodeView = itemView.findViewById(R.id.textModCodeView);
            textModuleDescView = itemView.findViewById(R.id.textModuleDescView);
            textEducatorView = itemView.findViewById(R.id.textEducatorView);
            textNoOfTestView = itemView.findViewById(R.id.textNoOfTestView);
            textNoOfAssView = itemView.findViewById(R.id.textNoOfAssView);
            textNoOfPracView = itemView.findViewById(R.id.textNoOfPracView);
            textNoOfExamView = itemView.findViewById(R.id.textNoOfExamView);
        }
    }
}

我已经导入了RecyclerView和CardView的依赖项。请帮忙。

Answer 1

此行从您的活动中获取“回收者”视图。我认为那不是你的意图。

recyclerView = (RecyclerView) getActivity().findViewById(R.id.recyclerView);

如果您确实在片段中定义了回收站视图，则应该从该片段中放大该布局，然后从那里找到recyclerview。

将片段中的视图放大并找到recyclerview的正确方法是

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_view_all_module, container, false);
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
    return rootView;
}

Answer 2

此行有错误，使您的应用崩溃：

recyclerView = (RecyclerView) getActivity().findViewById(R.id.recyclerView);

由于回收者视图不是MainActivity的一部分，因此在MainAcitvity的上下文中找到它会导致崩溃。您将需要从片段的XML文件中找到“膨胀的视图”，如下所示：

View view = inflater.inflate(R.layout.fragment_view_all_module, container, false);
recyclerView = view.findViewById(R.id.recyclerView);

然后在“回收者视图”上设置适配器和布局管理器。

一个建议：由于您的片段布局仅由一个Recycler View组成，因此您应该考虑使用FrameLayout作为该Recycler View的容器而不是LinearLayout，尽管这与崩溃无关，但是如果您打算仅添加RecyclerView（即单个项目），那么FrameLayout是一个更好的选择。

Answer 3

首先，您需要填充片段的布局，然后初始化RecyclerView。试试这个

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    ((MainActivity) getActivity()).setTitle("VIEW ALL MODULES");
   // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_view_all_module, container, false);
    recyclerView = view.findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    moduleList = new ArrayList<>();
    Module m1 = new Module(1, 1, 2, 3, 4, "ONT4101", "DEV SOFT", "NMU", "ITC", "Haskins");
    Module m2 = new Module(2, 1, 5, 37, 44, "AIN4002", "AI", "NMU", "ITC", "THUG LIFE");
    Module m3 = new Module(3, 2, 2, 13, 44, "ONT4300", "PROJECT", "NMU", "ITC", "Haskins");
    moduleList.add(m1);
    moduleList.add(m2);
    moduleList.add(m3);
    moduleAdapter = new ModuleAdapter(getActivity(), moduleList);
    recyclerView.setAdapter(moduleAdapter);
    return view;
}

希望这会有所帮助。

Answer 4

implementation 'com.google.android.material:material:1.2.1' // 在应用级 gradle 中使用这个

Recyclerview没有显示在片段中

4 个答案: