Java 如何在其他用户在后端更新数据时刷新列表视图
我有一个列表视图,其中包含几个来自后端的字段。一个提要是“喜欢的数量”。 当我单击任何列表行时,它会为该行打开一个活动,该活动中有一个like按钮。当用户按下时,它会被附加到服务器上。 现在的问题是,当用户返回列表视图活动时,它应该在列表视图中显示递增的值。怎么做 注意:如果我关闭应用程序并再次启动,Like计数器将增加。 我试图再次从on Resume方法调用Create方法,但每次删除列表视图活动时,它都会生成重复的行副本 这是我的列表活动代码Java 如何在其他用户在后端更新数据时刷新列表视图,java,android,json,listview,Java,Android,Json,Listview,我有一个列表视图,其中包含几个来自后端的字段。一个提要是“喜欢的数量”。 当我单击任何列表行时,它会为该行打开一个活动,该活动中有一个like按钮。当用户按下时,它会被附加到服务器上。 现在的问题是,当用户返回列表视图活动时,它应该在列表视图中显示递增的值。怎么做 注意:如果我关闭应用程序并再次启动,Like计数器将增加。 我试图再次从on Resume方法调用Create方法,但每次删除列表视图活动时,它都会生成重复的行副本 这是我的列表活动代码 public class MainActivi
public class MainActivity extends Activity {
// Session Manager Class
SessionManager session;
// Log tag
private static final String TAG = MainActivity.class.getSimpleName();
// Movies json url
private static final String url = "MY_URL";
private ProgressDialog pDialog;
private List<Movie> movieList = new ArrayList<Movie>();
private ListView listView;
private CustomListAdapter adapter;
{
// Creating volley request obj
JsonArrayRequest movieReq = new JsonArrayRequest(url,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
hidePDialog();
// Parsing json
for (int i = 0; i < response.length(); i++) {
try {
JSONObject obj = response.getJSONObject(i);
Movie movie = new Movie();
movie.setThumbnailUrl(obj.getString("image"));
movie.setTitle(obj.getString("title"));
movie.setDate(obj.getString("date"));
movie.setVideo(obj.getString("video"));
movie.setLikes(obj.getInt("likes"));
movie.setId(obj.getInt("id"));
// adding movie to movies array
movieList.add(movie);
} catch (JSONException e) {
e.printStackTrace();
}
}
// notifying list adapter about data changes
// so that it renders the list view with updated data
adapter.notifyDataSetChanged();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
hidePDialog();
}
});
// Adding request to request queue
AppController.getInstance().addToRequestQueue(movieReq);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//creating unique ID
final String deviceId = Settings.Secure.getString(this.getContentResolver(),
Settings.Secure.ANDROID_ID);
Toast.makeText(this, deviceId, Toast.LENGTH_SHORT).show();
Toast.makeText(getApplicationContext(), "User Login Status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show();
/**
* Call this function whenever you want to check user login
* This will redirect user to LoginActivity is he is not
* logged in
* */
session.checkLogin();
listView = (ListView) findViewById(R.id.list);
adapter = new CustomListAdapter(this, movieList);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// getting values from selected ListItem
// ImageView thumbNail = (ImageView)view.findViewById(R.id.thumbnail);
String title = ((TextView) view.findViewById(R.id.title)).getText().toString();
String likes = ((TextView)view.findViewById(R.id.likes)).getText().toString();
String date = ((TextView)view.findViewById(R.id.date)).getText().toString();
String video = ((TextView) view.findViewById(R.id.video)).getText().toString();
String idd = ((TextView) view.findViewById(R.id.idd)).getText().toString();
// Starting single contact activity
Intent in = new Intent(getApplicationContext(), MovieDetailActivity.class);
// in.putExtra("THUMB", thumbNail.toString());
in.putExtra("TITLE", title);
in.putExtra("LIKES", likes);
in.putExtra("DATE", date);
in.putExtra("VIDEO", video);
in.putExtra("IDD", idd);
in.putExtra("UNIQUEID",deviceId);
//in.putExtra(TAG_URL,"url");
// in.putExtra(TAG_PHONE_MOBILE, description);
startActivity(in);
}
}
);
// Creating volley request obj
enter code here
JsonArrayRequest movieReq = new JsonArrayRequest(url,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
hidePDialog();
// Parsing json
for (int i = 0; i < response.length(); i++) {
try {
JSONObject obj = response.getJSONObject(i);
Movie movie = new Movie();
movie.setThumbnailUrl(obj.getString("image"));
movie.setTitle(obj.getString("title"));
movie.setDate(obj.getString("date"));
movie.setVideo(obj.getString("video"));
movie.setLikes(obj.getInt("likes"));
movie.setId(obj.getInt("id"));
// adding movie to movies array
movieList.add(movie);
} catch (JSONException e) {
e.printStackTrace();
}
}
// notifying list adapter about data changes
// so that it renders the list view with updated data
adapter.notifyDataSetChanged();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
hidePDialog();
}
});
// Adding request to request queue
AppController.getInstance().addToRequestQueue(movieReq);
}
@Override
protected void onResume() {
super.onResume();
}
@Override
public void onDestroy() {
super.onDestroy();
hidePDialog();
}
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
public class CustomListAdapter extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<Movie> movieItems;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public CustomListAdapter(Activity activity, List<Movie> movieItems) {
this.activity = activity;
this.movieItems = movieItems;
}
@Override
public int getCount() {
return movieItems.size();
}
@Override
public Object getItem(int location) {
return movieItems.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_row, null);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView thumbNail = (NetworkImageView) convertView
.findViewById(R.id.thumbnail);
TextView title = (TextView) convertView.findViewById(R.id.title);
TextView likes = (TextView) convertView.findViewById(R.id.likes);
TextView date = (TextView) convertView.findViewById(R.id.date);
TextView video = (TextView) convertView.findViewById(R.id.video);
TextView id = (TextView) convertView.findViewById(R.id.idd);
//TextView year = (TextView) convertView.findViewById(R.id.releaseYear);
// getting movie data for the row
Movie m = movieItems.get(position);
// thumbnail image
thumbNail.setImageUrl(m.getThumbnailUrl(), imageLoader);
// title
title.setText(m.getTitle());
// rating
date.setText(m.getDate());
video.setText(m.getVideo());
likes.setText(String.valueOf(m.getLikes()));
id.setText(String.valueOf(m.getId()));
return convertView;
// Listview on item click listener
}
@Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
}
}
使用SortedList和RecyclerView请求实施: 这是我用来建造我的房子的例子 这是我的稍微复杂一些的代码,其中包括通过工具栏中的SearchView进行排序。如果希望示例不进行排序,可以使用上面链接中的示例。控制逻辑位于管理此适配器和片段的my Presenter类中: 当您调用任何批处理更新时,列表将在UI中自动更新自身。因此,当您获得初始数据时,只需调用addAllyourData,RecyclerView就会自动填充列表。当您获得更新的数据时,只需调用addAllyourNewData,RecyclerView将自动添加新项目并删除不存在的新项目,从而为您留下一个完全更新的列表。您需要确保实现SorterList。回调方法比较…、AreContentsSame…、AreItemsSame。。。以确保在添加/删除项目时,其行为符合您的要求
如果你需要更多的帮助,请告诉我。坦率地说,这种更新和排序数据的实现类型非常平滑。更改数据集后,调用adapter.notifyDataSetChanged;还要确保它是从主线发出的。这不是回答,而是建议。您会反对使用RecyclerView和SortedList吗?如果没有,则当您再次检索数据并将其应用于RecyclerView时,将使用更新的数据自动更新RecyclerView。它还可以防止重复。如果你有兴趣,请告诉我,我会发布。请发布@anxhatto
public class AdapterInstitutionList extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
// lists to control all items and items visible after sorting
private SortedList<MInstitutionInfo> visibleList;
private ArrayList<MInstitutionInfo> allItems;
// my fragment and the presenter
private FInstitutionSelection fInstitutionSelection;
private PInstitutionList presenter;
public AdapterInstitutionList(PInstitutionList pInstitutionSelection, FInstitutionSelection fInstitutionSelection) {
// get ref to fragment, presenter, and create new callback for sortedlist
this.fInstitutionSelection = fInstitutionSelection;
presenter = pInstitutionSelection;
visibleList = new SortedList<>(MInstitutionInfo.class, new InstitutionListCallback());
allItems = new ArrayList<>();
}
// inflate your list item view here
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.listitem_institution, parent, false);
return new InstitutionViewHolder(view);
}
// on binding, you populate your list item with the values, onclickhandle, etc
@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
InstitutionViewHolder institutionViewHolder = (InstitutionViewHolder) viewHolder;
final MInstitutionInfo institutionInfo = visibleList.get(position);
institutionViewHolder.setInstitutionInfo(institutionInfo);
institutionViewHolder.populateTextView();
institutionViewHolder.parent.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
presenter.onInstitutionSelected(institutionInfo);
}
});
}
@Override
public int getItemCount() {
return visibleList.size();
}
// my utility function for the presenter/fragment
public MInstitutionInfo get(int position) {
return visibleList.get(position);
}
public int add(MInstitutionInfo item) {
return visibleList.add(item);
}
public int indexOf(MInstitutionInfo item) {
return visibleList.indexOf(item);
}
public void updateItemAt(int index, MInstitutionInfo item) {
visibleList.updateItemAt(index, item);
}
public void addAll(List<MInstitutionInfo> items) {
visibleList.beginBatchedUpdates();
try {
for (MInstitutionInfo item : items) {
visibleList.add(item);
allItems.add(item);
}
} finally {
visibleList.endBatchedUpdates();
}
}
public void addAll(MInstitutionInfo[] items) {
addAll(Arrays.asList(items));
}
public boolean remove(MInstitutionInfo item) {
return visibleList.remove(item);
}
public MInstitutionInfo removeItemAt(int index) {
return visibleList.removeItemAt(index);
}
public void clearVisibleList() {
visibleList.beginBatchedUpdates();
try {
// remove items at end to remove unnecessary array shifting
while (visibleList.size() > 0) {
visibleList.removeItemAt(visibleList.size() - 1);
}
} finally {
visibleList.endBatchedUpdates();
}
}
public void clearAllItemsList() {
allItems.clear();
}
public void filterList(String queryText) {
clearVisibleList();
visibleList.beginBatchedUpdates();
try {
String constraint = queryText.toLowerCase();
for (MInstitutionInfo institutionInfo : allItems) {
if (institutionInfo.getName() != null && institutionInfo.getName().toLowerCase().contains(constraint)) {
visibleList.add(institutionInfo);
}
}
} finally {
visibleList.endBatchedUpdates();
}
}
public void clearFilter() {
if (visibleList.size() == allItems.size()) {
return;
}
clearVisibleList();
visibleList.beginBatchedUpdates();
try {
for (MInstitutionInfo institutionInfo : allItems) {
visibleList.add(institutionInfo);
}
} finally {
visibleList.endBatchedUpdates();
}
}
// the callback for the SortedList
// this manages the way in which items are added/removed/changed/etc
// mine is pretty simple
private class InstitutionListCallback extends SortedList.Callback<MInstitutionInfo> {
@Override
public int compare(MInstitutionInfo o1, MInstitutionInfo o2) {
return o1.getName().compareTo(o2.getName());
}
@Override
public void onInserted(int position, int count) {
notifyItemRangeInserted(position, count);
}
@Override
public void onRemoved(int position, int count) {
notifyItemRangeRemoved(position, count);
}
@Override
public void onMoved(int fromPosition, int toPosition) {
notifyItemMoved(fromPosition, toPosition);
}
@Override
public void onChanged(int position, int count) {
notifyItemRangeChanged(position, count);
}
@Override
public boolean areContentsTheSame(MInstitutionInfo oldItem, MInstitutionInfo newItem) {
return oldItem.getName().equals(newItem.getName());
}
@Override
public boolean areItemsTheSame(MInstitutionInfo item1, MInstitutionInfo item2) {
return item1.getName().equals(item2.getName());
}
}
// this is the view holder that is used for the list items
private class InstitutionViewHolder extends RecyclerView.ViewHolder {
public View parent;
public TextView tvName;
public MInstitutionInfo institutionInfo;
public InstitutionViewHolder(View itemView) {
super(itemView);
parent = itemView;
tvName = (TextView) itemView.findViewById(R.id.tv_institution_listitem_name);
}
public MInstitutionInfo getInstitutionInfo() {
return institutionInfo;
}
public void setInstitutionInfo(MInstitutionInfo institutionInfo) {
this.institutionInfo = institutionInfo;
}
public void populateTextView() {
if (tvName != null && institutionInfo != null && institutionInfo.getName() != null) {
tvName.setText(institutionInfo.getName());
}
}
}
myRecyclerView.setAdapter(myAdapter);