在 Fragment 中找不到符号变量 R

cannot find symbol variable R in Fragment

public class home extends Fragment{

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //returning our layout file
        //change R.layout.yourlayoutfilename for each of your fragments

        postlist = (ListView)getView().findViewById(R.id.postList);
        progressDialog = new ProgressDialog(getActivity());
        progressDialog.setMessage("Loading...");
        progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        progressDialog.show();

        StringRequest request = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
            @Override
            public void onResponse(String s) {
                gson = new Gson();
                list = (List) gson.fromJson(s, List.class);
                postTitle = new String[list.size()];

                for (int i = 0; i < list.size(); ++i) {
                    mapPost = (Map<String, Object>) list.get(i);
                    mapTitle = (Map<String, Object>) mapPost.get("title");
                    postTitle[i] = (String) mapTitle.get("rendered");
                }
                **postlist.setAdapter(new ArrayAdapter(getActivity(),android.R.layout.simple_list_item_1, postTitle));//R is not Resolved**
                progressDialog.dismiss();

            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError volleyerror) {
                Toast.makeText(getActivity(),"Some error occurred", Toast.LENGTH_LONG).show();

            }
        });

        return inflater.inflate(R.layout.home, container, false);
    }


    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        //you can set the title for your toolbar here for different fragments different titles
        getActivity().setTitle("Home");
    }
}

我收到错误:找不到符号变量 R。如何解决它。 相同的代码 运行 在 activity 中很好,但在 activity 中使用时会出错。

试试这个在片段中绑定你的控件

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

  View rootView = inflater.inflate(R.layout.home, container, false);

 postlist = (ListView)rootView.findViewById(R.id.postList);

  // your allll code
  return rootView;
}

试试这个代码

View rootView
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    if (rootView != null) {
        ViewGroup parent = (ViewGroup) rootView.getParent();
        if (parent != null)
            parent.removeView(rootView);
    }
    try {
        rootView = inflater.inflate(R.layout.home, container, false);
    } catch (InflateException e) {

    }



return rootView;
}

我刚刚发生了同样的事情。
我尝试按照建议引用 rootView,但错误仍然存​​在。
我尝试了构建 -> 清理和重建,但错误仍然存​​在。

我最终删除了我的片段和相应的布局,然后通过android Studio界面重新创建了一个新的片段 (New=>Fragment=>Fragment(Blank)),并实现了与之前完全相同的代码,并且运行良好。

我知道,这不是您正在寻找的解决方案,但在花了太多时间尝试我在网上找到的所有建议后,这是对我有用的唯一方法。

在您的导入中检查 android.R 并将其删除。

Android Studio 在将 java 代码转换为 Kotlin 时有时会添加它。