我四处搜寻，似乎没有任何效果。我有一个 RecyclerView 对象，除非我尝试创建无限滚动监听器事件，否则它运行完美。之后，它停止工作并返回一个空 View 。所以我删除了我添加的代码，但它仍然是相同的。我附上这些文件以供进一步引用。
fragment
public class Questions extends Fragment {
List<QuestionsItem> questionsItems;
String beforeString = "";
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_questions, null);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
// Equivalent to on Create
super.onViewCreated(view, savedInstanceState);
getActivity().setTitle("Questions");
recyclerView = view.findViewById(R.id.question_recycler);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setItemAnimator(new DefaultItemAnimator());
questionsItems = loadQuestions("recent", "all", beforeString, "0");
adapter = new QuestionsAdapter(questionsItems, getContext());
recyclerView.setAdapter(adapter);
}
public List<QuestionsItem> loadQuestions(String sort, String area, String before, String length) {
final List<QuestionsItem> questions = new ArrayList<>();
final API api = new API();
OkHttpClient client = new OkHttpClient();
RequestBody body = new FormBody.Builder()
.add("sort", sort)
.add("area", area)
.add("before", before)
.add("length", length)
.build();
Request request = api.call("q_loadmore", body, getContext(), getActivity());
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
MaterialDialog dialog = api.prepareDialog(getContext(), "An Error Occoured", "An Error Occoured. Please make sure you are connected to the internet and try again. If the issue still persists please contact support.");
dialog.show();
call.cancel();
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseText = response.body().string();
try {
JSONObject jsonObject = new JSONObject(responseText);
if (jsonObject.get("status").equals("ok"))
{
JSONObject payload = jsonObject.getJSONObject("payload");
JSONArray questionsArray = payload.getJSONArray("questions");
// TODO: Set Before String
//beforeString = payload.get("before").toString();
for (int i=0; i < questionsArray.length(); i++) {
JSONObject obj = questionsArray.getJSONObject(i);
String id = obj.get("qid").toString();
String title = obj.get("title").toString();
String postedBy = obj.get("postedBy").toString();
int views = obj.getInt("views");
int votes = obj.getInt("votes");
int answers = obj.getInt("answers");
int postedOn = obj.getInt("postedOn");
String[] tags = api.toStringArray(obj.getJSONArray("tags"));
QuestionsItem questionsItem = new QuestionsItem(id, title, tags, views, votes, answers, postedBy, postedOn);
questions.add(questionsItem);
}
}
else if (jsonObject.get("status").equals("error"))
{
MaterialDialog dialog = api.prepareDialog(getContext(), jsonObject.getJSONObject("dialog").get("title").toString(), jsonObject.getJSONObject("dialog").get("message").toString());
dialog.show();
}
else
{
MaterialDialog dialog = api.prepareDialog(getContext(), "An Error Occurred", "An Error Occurred. Please make sure you are connected to the internet and try again. If the issue still persists please contact support.");
dialog.show();
}
}
catch (JSONException e) {
e.printStackTrace();
}
}
});
return questions;
}
}
适配器
public class QuestionsAdapter extends RecyclerView.Adapter<QuestionsAdapter.ViewHolder> {
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView title;
public TextView date;
public TextView username;
public TextView stats;
public AutoLabelUI labels;
public ViewHolder(View itemView) {
super(itemView);
title = itemView.findViewById(R.id.ques_title);
date = itemView.findViewById(R.id.ques_time);
username = itemView.findViewById(R.id.ques_username);
stats = itemView.findViewById(R.id.ques_stats);
labels = itemView.findViewById(R.id.ques_labels);
}
}
private List<QuestionsItem> questionsItems;
private Context context;
public QuestionsAdapter(List<QuestionsItem> questionsItems, Context context) {
this.questionsItems = questionsItems;
this.context = context;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_questions, parent, false);
return new ViewHolder(v);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
QuestionsItem questionsItem = questionsItems.get(position);
holder.title.setText(questionsItem.getTitle());
holder.date.setText(DateTimeUtils.getTimeAgo(context, new Date(questionsItem.getPostedOn()), DateTimeStyle.AGO_FULL_STRING));
holder.username.setText("@" + questionsItem.getPostedBy());
holder.stats.setText(questionsItem.getViews() + " views " + questionsItem.getVotes() + " votes " + questionsItem.getAnswers() + " answers");
AutoLabelUISettings autoLabelUISettings = new AutoLabelUISettings.Builder()
.withMaxLabels(5)
.withShowCross(false)
.withLabelsClickables(false)
.build();
holder.labels.setSettings(autoLabelUISettings);
String[] tags = questionsItem.getTags();
for (String tag: tags) {
holder.labels.addLabel(tag);
}
}
@Override
public int getItemCount() {
return questionsItems.size();
}
}
型号
public class QuestionsItem {
private String id;
private String title;
private String[] tags;
private int views;
private int votes;
private int answers;
private String postedBy;
private int postedOn;
public QuestionsItem(String id, String title, String[] tags, int views, int votes, int answers, String postedBy, int postedOn) {
this.id = id;
this.title = title;
this.tags = tags;
this.views = views;
this.votes = votes;
this.answers = answers;
this.postedBy = postedBy;
this.postedOn = postedOn;
}
public String getId() {
return id;
}
public String getTitle() {
return title;
}
public String[] getTags() {
return tags;
}
public int getViews() {
return views;
}
public int getVotes() {
return votes;
}
public int getAnswers() {
return answers;
}
public String getPostedBy() {
return postedBy;
}
public int getPostedOn() {
return postedOn;
}
}
最佳答案
当您在 loadQuestions() 中返回问题时，它是空的，因为 onresponse 回调在服务器响应后执行。
在您的适配器类中添加一个方法 setQuestions 来设置问题。
public void setQuestions(List<QuestionsItem> questions) {
this.questions = questions;
}
在 onResponse 中添加以下内容:
// return void here
public void loadQuestions(String sort, String area, String before, String length) {
final List<QuestionsItem> questions = new ArrayList<>();
final API api = new API();
OkHttpClient client = new OkHttpClient();
RequestBody body = new FormBody.Builder()
.add("sort", sort)
.add("area", area)
.add("before", before)
.add("length", length)
.build();
Request request = api.call("q_loadmore", body, getContext(), getActivity());
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
MaterialDialog dialog = api.prepareDialog(getContext(), "An Error Occoured", "An Error Occoured. Please make sure you are connected to the internet and try again. If the issue still persists please contact support.");
dialog.show();
call.cancel();
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseText = response.body().string();
try {
JSONObject jsonObject = new JSONObject(responseText);
if (jsonObject.get("status").equals("ok"))
{
JSONObject payload = jsonObject.getJSONObject("payload");
JSONArray questionsArray = payload.getJSONArray("questions");
// TODO: Set Before String
//beforeString = payload.get("before").toString();
for (int i=0; i < questionsArray.length(); i++) {
JSONObject obj = questionsArray.getJSONObject(i);
String id = obj.get("qid").toString();
String title = obj.get("title").toString();
String postedBy = obj.get("postedBy").toString();
int views = obj.getInt("views");
int votes = obj.getInt("votes");
int answers = obj.getInt("answers");
int postedOn = obj.getInt("postedOn");
String[] tags = api.toStringArray(obj.getJSONArray("tags"));
QuestionsItem questionsItem = new QuestionsItem(id, title, tags, views, votes, answers, postedBy, postedOn);
questions.add(questionsItem);
}
// Set questions array in your adapter class
mQuestionAdapter.setQuestions(questions);
mQuestionAdapter.notifyDatasetChanged();
}
else if (jsonObject.get("status").equals("error"))
{
MaterialDialog dialog = api.prepareDialog(getContext(), jsonObject.getJSONObject("dialog").get("title").toString(), jsonObject.getJSONObject("dialog").get("message").toString());
dialog.show();
}
else
{
MaterialDialog dialog = api.prepareDialog(getContext(), "An Error Occurred", "An Error Occurred. Please make sure you are connected to the internet and try again. If the issue still persists please contact support.");
dialog.show();
}
}
catch (JSONException e) {
e.printStackTrace();
}
}
});
// remove return statement
}
关于java - RecyclerView 返回空，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47734136/