android - 尽管调用了 adapterlist.clear() ，但有时会得到空的 RecyclerVew 项目

Question

我正在尝试在从 Web 服务获得的 recyclerview 中显示学生的详细信息。该应用程序的工作方式是在 Activity 中打开学生列表，然后在触摸学生时，它会打开另一个 Activity，该 Activity 将在回收站视图中显示该特定学生的详细信息。
问题：
我有时会在带有数据的有效项目上方或下方得到一个空的 recyclerview 项目。我试着打电话 StuDetailsDataAdapterClassList.clear();，但它不能解决问题。有时它工作正常，但我不明白为什么会这样。你的帮助对我很有价值。

public class StudentDetailsActivity extends AppCompatActivity {

RecyclerView recyclerView;
RecyclerView recyclerView2;
RecyclerView.Adapter recyclerViewAdapter;
RecyclerView.Adapter recyclerViewAdapter2;
LinearLayoutManager recyclerViewlayoutManager;
RequestQueue requestQueue ;
RequestQueue requestQueue2 ;
List<StudentDataModel> StuDetailsDataAdapterClassList;
String stuIDForParse;
StudentDataModel GetStuDataModel = new StudentDataModel();
.....


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_personnel_details);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    collapsingToolbarLayout = (SubtitleCollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
    recyclerView = (RecyclerView) findViewById(R.id.recyclerView4);
    recyclerView2 =(RecyclerView)findViewById(R.id.recyclerView5);
    recyclerViewlayoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(recyclerViewlayoutManager);

    StuDetailsDataAdapterClassList=new ArrayList<>();

    LinearLayoutManager layoutManager
            = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
    recyclerView2.setLayoutManager(layoutManager);
    //I have a horizontal recyclerview below the vertical recyclerview. This is the layout manager for that recyclerview.
    recyclerView2.setNestedScrollingEnabled(false);
    //Set collapse & expanded title color
    collapsingToolbarLayout.setExpandedSubtitleTextColor(getResources().getColor(R.color.divider));
    setSupportActionBar(toolbar);
    //Enable back button
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDisplayShowHomeEnabled(true);
    ....
     //clearing list
    StuDetailsDataAdapterClassList.clear();
    PIC__WEB_CALL();
    STU_WEB_CALL();


}

public void STU_WEB_CALL(){

    String HTTP_SERVER_URL= String.format("http://www.student.com/%1$s",stuIDForParse);

    JsonArrayRequest jsArrRequest = new JsonArrayRequest
            (Request.Method.GET, HTTP_SERVER_URL, null, new Response.Listener<JSONArray>() {

                @Override
                public void onResponse(JSONArray response) {

                    RES_PER_PARSE_DATA_AFTER_WEBCALL(response);

                }
            }, new Response.ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {
                    // TODO Auto-generated method stub

                }
            }){

    };

    requestQueue = Volley.newRequestQueue(this);

    requestQueue.add(jsArrRequest);

}



public void RES_PER_PARSE_DATA_AFTER_WEBCALL(JSONArray array){

    for(int i = 0; i<array.length(); i++) {



        JSONObject json = null;
        try {
            json = array.getJSONObject(i);

            GetStuDataModel.setDob(json.getString("Date_Of_Birth"));

            GetStuDataModel.setStuName(json.getString("Name"));

            GetStuDataModel.setGradeName(json.getString("Grade"));

            //Set the title on collapsing toolbar
            collapsingToolbarLayout.setTitle(GetStuDataModel.getFullName());

        } catch (JSONException e) {

            e.printStackTrace();
        }

    }
    if (array.length() != 0) {
        StuDetailsDataAdapterClassList.add(GetStuDataModel);
        collapsingToolbarLayout.setSubtitle(GetStuDataModel.getPerTitle());
        recyclerViewAdapter = new StudentDetailsAdapter(StuDetailsDataAdapterClassList, this);
        recyclerView.setAdapter(recyclerViewAdapter);

    }

}


public void Horizontal_RecyclerView_WEB_CALL(){

 //....more code
}

适配器

public class StudentDetailsAdapter extends RecyclerView.Adapter<StudentDetailsAdapter.ViewHolder> {



Context context;

public List<StudentDataModel> dataModels;


public StudentDetailsAdapter(List<StudentDataModel> getDataAdapter, Context context){

    super();
    Log.i("LPLP","I'm here");
    this.dataModels = getDataAdapter;
    this.context = context;

}



@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.student_details_card, parent, false);

    ViewHolder viewHolder = new ViewHolder(view);

    return viewHolder;

}

@Override
public void onBindViewHolder(final StudentDetailsAdapter.ViewHolder viewHolder, final int position) {

    final StudentDataModel dataAdapter =  dataModels.get(position);

    viewHolder.grade.setText(dataAdapter.getGradeName());

    viewHolder.stuName.setText(dataAdapter.getStuName());

    viewHolder.dob.setText(dataAdapter.getDob());


}


@Override
public int getItemCount() {

    return dataModels.size();
}


class ViewHolder extends RecyclerView.ViewHolder{

    public TextView grade;
    public TextView stuName;
    public TextView dob;
    ConstraintLayout constraintLayout;

    public ViewHolder(View itemView) {

        super(itemView);

        grade=(TextView)itemView.findViewById(R.id.textViewGrade);
        stuName=(TextView)itemView.findViewById(R.id.textViewStuName);
        dob=(TextView)itemView.findViewById(R.id.textViewDOB)
        constraintLayout=(ConstraintLayout)itemView.findViewById(R.id.constrainLayout);

    }
}

}

标签： androidandroid-recyclerview