Develop Reference

Cannot insert value in Room Database Android

I am trying to insert info about movie but I am getting this error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void kawi15.myapplication.database.DatabaseViewModel.addWatchlistMovie(info.movito.themoviedbapi.model.MovieDb)' on a null object reference
I am sure that Movie is not null because I have Toast which showing me info about this movie.
I find that I need initializate DatabaseViewModel in my OnCreate():
databaseViewModel = new ViewModelProvider(this).get(DatabaseViewModel.class);
but I tried this in OnCreate and OnCreateView and in both its error with 'this':
new ViewModelProvider(this)
I try to put there getContext() or some other stuff but nothing worked here.
This is my Entity class:
#Entity
public class Watchlist {
#PrimaryKey
#ColumnInfo(name = "id")
private int movieId;
#ColumnInfo(name = "movie_title")
private String movieTitle;
#ColumnInfo(name = "poster_path")
private String posterPath;
#ColumnInfo(name = "overview")
private String overview;
#ColumnInfo(name = "release_date")
private String releaseDate;
and getters and setters for all
My Dao class:
#Dao
public interface WatchlistDao {
#Query("SELECT * FROM watchlist ORDER BY movie_title ASC")
List<Watchlist> getAll();
#Insert
void addMovie(Watchlist watchlistMovie);
}
ViewModel class:
public class DatabaseViewModel extends AndroidViewModel {
private AppDatabase db;
public DatabaseViewModel(#NonNull Application application) {
super(application);
db = AppDatabase.getDatabase(application);
}
public void addWatchlistMovie(MovieDb movieDb){
Watchlist addedMovie = new Watchlist();
addedMovie.setMovieId(movieDb.getId());
addedMovie.setMovieTitle(movieDb.getOriginalTitle());
addedMovie.setOverview(movieDb.getOverview());
addedMovie.setPosterPath(movieDb.getPosterPath());
addedMovie.setReleaseDate(movieDb.getReleaseDate());
db.watchlistDao().addMovie(addedMovie);
}
My Fragment class where I am clicking on Movie from list that I want to insert to database:
public class FragmentOne extends Fragment /*implements CustomAdapter.ListItemClickListener*/{
private static RecyclerView.Adapter adapter;
private RecyclerView.LayoutManager layoutManager;
private DatabaseViewModel databaseViewModel;
private static RecyclerView recyclerView;
private List<MovieDb> data;
//private CustomAdapter.ListItemClickListener mOnClickListener;
public static FragmentOne newInstance() {
FragmentOne fragment = new FragmentOne();
return fragment;
}
/*#Override
public void onListItemClick(int position) {
Toast.makeText(getContext(), data.get(position).getOriginalTitle(), LENGTH_SHORT).show();
}*/
public class MovieTask extends AsyncTask<Void, Void, List<MovieDb>> {
#Override
protected List<MovieDb> doInBackground(Void... voids) {
MovieResultsPage movies = new TmdbApi("f753872c7aa5c000e0f46a4ea6fc49b2").getMovies().getUpcoming("en-US", 1, "US");
List<MovieDb> listMovies = movies.getResults();
return listMovies;
}
#Override
protected void onPostExecute(List<MovieDb> movieDb) {
data = movieDb;
adapter = new CustomAdapter(data);
((CustomAdapter) adapter).setOnMovieDbClicked(movieDb2 -> {
Toast.makeText(getActivity(), movieDb2.getReleaseDate(), LENGTH_SHORT).show();
databaseViewModel.addWatchlistMovie(movieDb2);
});
recyclerView.setAdapter(adapter);
}
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View returnView = inflater.inflate(R.layout.fragment_one, container, false);
recyclerView = (RecyclerView) returnView.findViewById(R.id.my_recycler_view);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(getContext()); // ???
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
MovieTask mt = new MovieTask();
mt.execute();
return returnView;
}
}
and my adapter class, maybe not neccessary:
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.MyViewHolder>{
private List<MovieDb> dataSet;
private OnMovieDbClicked onMovieDbClicked;
public void setOnMovieDbClicked(OnMovieDbClicked onMovieDbClicked) {
this.onMovieDbClicked = onMovieDbClicked;
}
//final private ListItemClickListener mOnClickListener;
public class MyViewHolder extends RecyclerView.ViewHolder /*implements View.OnClickListener*/{
TextView textViewName;
TextView textViewVersion;
ImageView imageViewIcon;
//private ListItemClickListener mOnClickListener;
public MyViewHolder(View itemView) {
super(itemView);
this.textViewName = (TextView) itemView.findViewById(R.id.text1);
this.textViewVersion = (TextView) itemView.findViewById(R.id.text2);
this.imageViewIcon = (ImageView) itemView.findViewById(R.id.imageView);
itemView.setOnClickListener(view -> {
int pos = getAdapterPosition();
if (onMovieDbClicked != null && pos != RecyclerView.NO_POSITION) {
MovieDb movieDb = dataSet.get(pos);
onMovieDbClicked.movieDbClicked(movieDb);
}
});
//itemView.setOnClickListener(this);
//itemView.setOnClickListener(CustomAdapter.myOnClickListener);
}
/*#Override
public void onClick(View v) {
int position = getAdapterPosition();
mOnClickListener.onListItemClick(position);
}*/
}
public CustomAdapter(List<MovieDb> data /*ListItemClickListener mOnClickListener*/) {
this.dataSet = data;
//this.mOnClickListener = mOnClickListener;
}
public interface OnMovieDbClicked {
void movieDbClicked(MovieDb movieDb);
}
/*public interface ListItemClickListener{
void onListItemClick(int position);
}*/
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.cards_layout, parent, false);
//view.setOnClickListener(FragmentOne.myOnClickListener);
MyViewHolder myViewHolder = new MyViewHolder(view);
return myViewHolder;
}
#Override
public void onBindViewHolder(final MyViewHolder holder, final int listPosition) {
TextView textViewName = holder.textViewName;
TextView textViewVersion = holder.textViewVersion;
ImageView imageView = holder.imageViewIcon;
Glide.with(imageView).load("https://image.tmdb.org/t/p/w500" + dataSet.get(listPosition).getPosterPath()).into(imageView);
textViewName.setText(dataSet.get(listPosition).getOriginalTitle());
textViewVersion.setText(dataSet.get(listPosition).getReleaseDate());
}
#Override
public int getItemCount() {
if(dataSet == null){
return 0;
}
return dataSet.size();
}
}

You have not initialized your databaseViewModel anywhere so the NPE is expected. Make sure to fill the field before accessing it in MovieTask

Deleting In Room Database

I am learning Room DataBase!!
I Know How to Insert and Retrieve Data from Room DataBase to Recycler View!! But In Delete Operation I am getting error of "No Adapter attached Skipped Layout!"
What I want when anyone click on delete button on recycler view . The Task should be deleted
That's why I also Used delete method in Interface and add Interface in Recycler View Adapter which give call back to MainActivity so that we delete and update the recycler view
All of my codes are given below
Here is my Entity Class named as Task
#Entity
public class Task implements Serializable {
#PrimaryKey(autoGenerate = true)
private int id;
#ColumnInfo(name = "task_name")
private String task_name;
#ColumnInfo
private String task_desc;
#ColumnInfo
private String comment;
#ColumnInfo
private String task_comp_date;
#ColumnInfo
private String activate;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getTask_name() {
return task_name;
}
public void setTask_name(String task_name) {
this.task_name = task_name;
}
public String getTask_desc() {
return task_desc;
}
public void setTask_desc(String task_desc) {
this.task_desc = task_desc;
}
public String getTask_comp_date() {
return task_comp_date;
}
public void setTask_comp_date(String task_comp_date) {
this.task_comp_date = task_comp_date;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getActivate() {
return activate;
}
public void setActivate(String activate) {
this.activate = activate;
}
}
My Data Accession Object named as TaskDao
#Dao
public interface TaskDao {
#Query("SELECT * FROM task")
List<Task> getAll();
#Insert
void insert(Task task);
#Delete
void delete(Task task);
#Update
void update(Task task);
}
My DataBase
#Database(entities = {Task.class},version = 1)
public abstract class AppDataBase extends RoomDatabase {
public abstract TaskDao taskDao();
}
My DataBaseClient named as DatabaseClient
public class DatabaseClient {
private Context context;
private static DatabaseClient mInstace;
private AppDataBase appDataBase;
public DatabaseClient(Context context) {
this.context = context;
appDataBase = Room.databaseBuilder(context,AppDataBase.class,"MyDailyTask").build();
}
public static synchronized DatabaseClient getInstance(Context context)
{
if(mInstace == null)
{
mInstace = new DatabaseClient(context);
}
return mInstace;
}
public AppDataBase getAppDataBase()
{
return appDataBase;
}
}
My RecyclerView Adapter
public class TaskAdapter extends RecyclerView.Adapter<TaskAdapter.MyViewHolder> {
private Context context;
private List<Task> taskList;
public interface OnDeleteClickListener
{
void OnDeleteClickListener(Task task);
}
private OnDeleteClickListener onDeleteClickListener;
public TaskAdapter(Context context, List<Task> taskList) {
this.context = context;
this.taskList = taskList;
}
public void setOnDeleteClickListener(OnDeleteClickListener onDeleteClickListener) {
this.onDeleteClickListener = onDeleteClickListener;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view;
view = LayoutInflater.from(context).inflate(R.layout.view_task_list,parent,false);
MyViewHolder myViewHolder = new MyViewHolder(view);
return myViewHolder;
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int position) {
holder.setData(taskList.get(position).getTask_name(),taskList.get(position).getTask_desc(),taskList.get(position).getComment(),taskList.get(position).getTask_comp_date(),position);
}
#Override
public int getItemCount() {
return taskList.size();
}
class MyViewHolder extends RecyclerView.ViewHolder {
private TextView t1,t2,t3,t4,t5;
private ImageView view;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
t1= itemView.findViewById(R.id.tvCommnt);
t2=itemView.findViewById(R.id.tvDesc);
t3=itemView.findViewById(R.id.tvName);
t4= itemView.findViewById(R.id.tvStart);
t5 = itemView.findViewById(R.id.tvEnd);
view =itemView.findViewById(R.id.tvdele);
}
public void setData(String t01, String t02, String t03, String t05, final int position)
{
t1.setText("Task Comment "+t03);
t2.setText("Task Description "+t02);
t3.setText("Task Name "+ t01);
t4.setText("Start ");
t5.setText("Ënd "+t05);
view.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(onDeleteClickListener!=null)
{
onDeleteClickListener.OnDeleteClickListener(taskList.get(position));
taskList.remove(position);
notifyDataSetChanged();
}
}
});
}
}
}
MainActivity.java :
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
ImageView imageView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageView = findViewById(R.id.ivAdd);
recyclerView = findViewById(R.id.rvTask);
imageView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(getApplicationContext(), AddTaskActivity.class));
}
});
new newTask().execute();
}
class newTask extends AsyncTask<Void,Void, List<Task>> implements TaskAdapter.OnDeleteClickListener {
List<Task> tasks;
#Override
protected List<Task> doInBackground(Void... voids) {
tasks = DatabaseClient.getInstance(getApplicationContext()).getAppDataBase().taskDao().getAll();
return tasks;
}
#Override
protected void onPostExecute(List<Task> tasks) {
super.onPostExecute(tasks);
TaskAdapter taskAdapter = new TaskAdapter(MainActivity.this,tasks);
LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.addItemDecoration(new DividerItemDecoration(getApplicationContext(),DividerItemDecoration.VERTICAL));
recyclerView.setAdapter(taskAdapter);
taskAdapter.setOnDeleteClickListener(this);
}
#Override
public void OnDeleteClickListener(final Task task) {
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
DatabaseClient.getInstance(getApplicationContext()).getAppDataBase().taskDao().delete(task);
}
},1000);
}
}

welcome in stack
you interface is declared but not assign so your will throw null pointer when click on item inside your list, but good work your check null before fire method interface
first add setter for OnDeleteClickListener inside your adapter
public void setOnDeleteClickListener(OnDeleteClickListener listener){
this.onDeleteClickListener=listener;
}
and also add code that remove item from you list when user click item
so inside setData method update this code
view.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (onDeleteClickListener != null) {
onDeleteClickListener.OnDeleteClickListener(taskList.get(position));
//remove item from list and then notify adapter data is changed
taskList.remove(position);
notifyDataSetChanged();
}
}
});
finally to Triggers onDeleteClickListener inside your AsyncTask
update your code here
#Override
protected void onPostExecute(List < Task > tasks) {
super.onPostExecute(tasks);
TaskAdapter taskAdapter = new TaskAdapter(MainActivity.this, tasks, this);
LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.addItemDecoration(new DividerItemDecoration(getApplicationContext(), DividerItemDecoration.VERTICAL));
recyclerView.setAdapter(taskAdapter);
//pass this that refer to my interface
taskAdapter.setOnDeleteClickListener(this);
}
inside your OnDelete just use this code to run in another thread
AsyncTask.execute(new Runnable() {
#Override
public void run() {
DatabaseClient.getInstance(getApplicationContext()).getAppDataBase().taskDao().delete(task);
}
});
Advice : Don't name your variable or arguments like String
t01,String t02..etc ,choice name for like what this variable jop
like String taskComment,String taskName ..etc
i hope this help you

How can I get a variable from RecyclerView Adapter passed to MainActivity?

I was just playing around with some code, learning new things, when I ran into this problem... I'm trying to pass a variable from my RecylcerViewAdapter to a method in MainActivity, but I just can't seem to accomplish it.
I tried a lot of different thing with interfaces and casting, but nothing did the trick. Since I'm fairly new to all of this, maybe I'm making a trivial mistake somewhere?
My Interface:
public interface AdapterCallback {
void onMethodCallback(int id);
}
This is my adapter class:
public class PostAdapter extends RecyclerView.Adapter<PostAdapter.ViewHolder> {
private List<Post> postList;
private Context context;
private AdapterCallback listener;
public PostAdapter() {
}
public PostAdapter(List<Post> postList, Context context) {
this.postList = postList;
this.context = context;
}
public void setListener(AdapterCallback listener) {
this.listener = listener;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.recycler_layout, viewGroup, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolder viewHolder, final int position) {
viewHolder.tvTitle.setText(postList.get(position).getTitle());
viewHolder.tvBody.setText(new StringBuilder(postList.get(position).getBody().substring(0, 20)).append("..."));
viewHolder.tvId.setText(String.valueOf(postList.get(position).getUserId()));
viewHolder.parentLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int id = postList.get(position).getId();
if (listener != null) {
listener.onMethodCallback(id);
}
}
});
}
#Override
public int getItemCount() {
return postList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView tvTitle;
TextView tvBody;
TextView tvId;
LinearLayout parentLayout;
public ViewHolder(View itemView) {
super(itemView);
tvTitle = itemView.findViewById(R.id.tvTitle);
tvBody = itemView.findViewById(R.id.tvBody);
tvId = itemView.findViewById(R.id.tvId);
parentLayout = itemView.findViewById(R.id.parentLayout);
}
}
}
And my MainActivity:
public class MainActivity extends AppCompatActivity {
public static final String TAG = "MainActivityLog";
private CompositeDisposable disposable = new CompositeDisposable();
#BindView(R.id.rvPosts)
RecyclerView rvPosts;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
rvPosts.setHasFixedSize(true);
rvPosts.setLayoutManager(new LinearLayoutManager(this));
populateList();
logItems();
}
private void populateList() {
MainViewModel viewModel = ViewModelProviders.of(MainActivity.this).get(MainViewModel.class);
viewModel.makeQuery().observe(MainActivity.this, new Observer<List<Post>>() {
#Override
public void onChanged(#Nullable List<Post> posts) {
PostAdapter adapter = new PostAdapter(posts, getApplicationContext());
rvPosts.setAdapter(adapter);
}
});
}
public void logItems() {
PostAdapter adapter = new PostAdapter();
adapter.setListener(new AdapterCallback() {
#Override
public void onMethodCallback(int id) {
MainViewModel viewModel = ViewModelProviders.of(MainActivity.this).get(MainViewModel.class);
viewModel.makeSingleQuery(id).observe(MainActivity.this, new Observer<Post>() {
#Override
public void onChanged(#Nullable final Post post) {
Log.d(TAG, "onChanged: data response");
Log.d(TAG, "onChanged: " + post);
}
});
}
});
}
#Override
protected void onDestroy() {
super.onDestroy();
disposable.clear();
}
}
The populateList() method works just fine, but the logItems() method is the problem.
So when i click on a view in RecyclerView I expect the log to output the title, description and ID of the post that was clicked. nut nothing happens...
So, any help would be appreciated.

Make adapter global variable i.e. a field. Use the same object to set every properties.
private PostAdapter adapter;
Replace your logItems method with this:
public void logItems() {
adapter.setListener(new AdapterCallback() {
#Override
public void onMethodCallback(int id) {
MainViewModel viewModel = ViewModelProviders.of(MainActivity.this).get(MainViewModel.class);
viewModel.makeSingleQuery(id).observe(MainActivity.this, new Observer<Post>() {
#Override
public void onChanged(#Nullable final Post post) {
Log.d(TAG, "onChanged: data response");
Log.d(TAG, "onChanged: " + post);
}
});
}
});
}
And populateList with this:
private void populateList() {
MainViewModel viewModel = ViewModelProviders.of(MainActivity.this).get(MainViewModel.class);
viewModel.makeQuery().observe(MainActivity.this, new Observer<List<Post>>() {
#Override
public void onChanged(#Nullable List<Post> posts) {
adapter = new PostAdapter(posts, getApplicationContext());
rvPosts.setAdapter(adapter);
logItems();
}
});
}
And don't call logItems() from onCreate

This is how I implement with my ListAdapters:
public class FeedbackListAdapter extends RecyclerView.Adapter<FeedbackListAdapter.ViewHolder> {
private final ArrayList<Feedback> feedbacks;
private View.OnClickListener onItemClickListener;
private View.OnLongClickListener onItemLongClickListener;
private final Context context;
public FeedbackListAdapter(ArrayList<Feedback> feedbacks, Context context) {
this.feedbacks = feedbacks;
this.context = context;
}
public void setItemClickListener(View.OnClickListener onItemClickListener) {
this.onItemClickListener = onItemClickListener;
}
public void setOnItemLongClickListener(View.OnLongClickListener onItemLongClickListener){
this.onItemLongClickListener = onItemLongClickListener;
}
public class ViewHolder extends RecyclerView.ViewHolder{
final TextView feedback, created, updated;
final LinearLayout mainLayout;
ViewHolder(View iv) {
super(iv);
/*
* Associate layout elements to Java declarations
* */
mainLayout = iv.findViewById(R.id.main_layout);
feedback = iv.findViewById(R.id.feedback);
created = iv.findViewById(R.id.created_string);
updated = iv.findViewById(R.id.updated_string);
}
}
#Override
public int getItemCount() {
return feedbacks.size();
}
#Override
#NonNull
public FeedbackListAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fragment_feedback_table_row, parent, false);
return new FeedbackListAdapter.ViewHolder(view);
}
#Override
public void onBindViewHolder(final #NonNull FeedbackListAdapter.ViewHolder holder, final int position) {
/*
* Bind data to layout
* */
try{
Feedback feedback = feedbacks.get(position);
holder.feedback.setText(feedback.getContent());
holder.created.setText(feedback.getCreated());
holder.updated.setText(feedback.getUpdated());
holder.mainLayout.setOnClickListener(this.onItemClickListener);
holder.mainLayout.setOnLongClickListener(this.onItemLongClickListener);
holder.mainLayout.setTag(feedback.getDbID());
TypedValue outValue = new TypedValue();
context.getTheme().resolveAttribute(android.R.attr.selectableItemBackground, outValue, true);
holder.mainLayout.setBackgroundResource(outValue.resourceId);
}catch(IndexOutOfBoundsException e){
e.printStackTrace();
}
}
}

In onPopulateList you create an adaptor:
PostAdapter adapter = new PostAdapter(posts, getApplicationContext());
rvPosts.setAdapter(adapter);
However in public void logItems() { you used a different adapter
PostAdapter adapter = new PostAdapter();
adapter.setListener(new AdapterCallback() {
#Override
public void onMethodCallback(int id) {
...
}
});
Therefore the list is being populated with 1 adapter, but you are setting the listener on an unused second adapter.
The fix is to use the same adapter for both. If you make the adapater a field, and don't create a new one inside of logItems, but just set your listener it should work.
i.e.
// as a field in your class
private PostAdapter adapter;
then
// in `populateList()`
adapter = new PostAdapter(posts, getApplicationContext());
rvPosts.setAdapter(adapter);
and
// in `logItems()`
adapter.setListener(new AdapterCallback() {
#Override
public void onMethodCallback(int id) {
...
}
});

In Adapter
public class CustomerListAdapter extends RecyclerView.Adapter<CustomerListAdapter.OrderItemViewHolder> {
private Context mCtx;
ProgressDialog progressDialog;
//we are storing all the products in a list
private List<CustomerModel> customeritemList;
public CustomerListAdapter(Context mCtx, List<CustomerModel> orderitemList) {
this.mCtx = mCtx;
this.customeritemList = orderitemList;
progressDialog = new ProgressDialog(mCtx);
}
#NonNull
#Override
public OrderItemViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(mCtx);
View view = inflater.inflate(R.layout.activity_customer_list, null);
return new OrderItemViewHolder(view, mCtx, customeritemList);
}
#Override
public void onBindViewHolder(#NonNull OrderItemViewHolder holder, int position) {
CustomerModel customer = customeritemList.get(position);
try {
//holder.textViewPINo.setText("PINo \n"+Integer.toString( order.getPINo()));
holder.c_name.setText(customer.getCustomerName());
holder.c_address.setText(customer.getAddress());
holder.c_contact.setText(customer.getMobile());
holder.i_name.setText(customer.getInteriorName());
holder.i_contact.setText(customer.getInteriorMobile());
holder.i_address.setText(customer.getAddress());
} catch (Exception E) {
E.printStackTrace();
}
}
#Override
public int getItemCount() {
return customeritemList.size();
}
class OrderItemViewHolder extends RecyclerView.ViewHolder implements View.OnLongClickListener, View.OnClickListener {
AlertDialog.Builder alert;
private Context mCtx;
TextView c_name, c_contact, c_address, i_name, i_contact, i_address;
TextView OrderItemID, MaterialType, Price2, Qty, AQty;
//we are storing all the products in a list
private List<CustomerModel> orderitemList;
public OrderItemViewHolder(View itemView, Context mCtx, List<CustomerModel> orderitemList) {
super(itemView);
this.mCtx = mCtx;
this.orderitemList = orderitemList;
itemView.setOnClickListener(this);
itemView.setOnLongClickListener(this);
// CatelogOrderDetailModel catelogOrderDetailModel = new CatelogOrderDetailModel();
c_name = itemView.findViewById(R.id.customerName);
c_contact = itemView.findViewById(R.id.contact);
c_address = itemView.findViewById(R.id.address);
i_name = itemView.findViewById(R.id.interiorName);
i_address = itemView.findViewById(R.id.interiorAddress);
i_contact = itemView.findViewById(R.id.interiorContact);
}
#Override
public void onClick(View v) {
int position = getAdapterPosition();
CustomerModel orderitem = this.orderitemList.get(position);
}
#Override
public boolean onLongClick(View v) {
int position = getAdapterPosition();
CustomerModel orderitem = this.orderitemList.get(position);
if (v.getId() == itemView.getId()) {
// showUpdateDeleteDialog(order);
try {
} catch (Exception E) {
E.printStackTrace();
}
Toast.makeText(mCtx, "lc: ", Toast.LENGTH_SHORT).show();
}
return true;
}
}
}

I want to display an image from drawable and combine it with data from json-api into recylerview

I have an application project for news media using java programming, I
want to display images for categories from drawable into recylerview
that are based on json-api, is there any one who can help me?
How I do for load image from drawable and combine it with data from json-api into RecylerView can anyone provide specific code here
this is my AdapterCategory.java
public class AdapterCategory extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<Category> items = new ArrayList<>();
private Context ctx;
private OnItemClickListener mOnItemClickListener;
private int c;
public interface OnItemClickListener {
void onItemClick(View view, Category obj, int position);
}
public void setOnItemClickListener(final OnItemClickListener mItemClickListener) {
this.mOnItemClickListener = mItemClickListener;
}
// Provide a suitable constructor (depends on the kind of dataset)
public AdapterCategory(Context context, List<Category> items) {
this.items = items;
ctx = context;
}
public class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView name;
public TextView post_count;
public LinearLayout lyt_parent;
public ImageView imageView;
public ViewHolder(View v) {
super(v);
name = (TextView) v.findViewById(R.id.name);
post_count = (TextView) v.findViewById(R.id.post_count);
imageView = (ImageView)v.findViewById(R.id.image_category);
lyt_parent = (LinearLayout) v.findViewById(R.id.lyt_parent);
//imageView.setImageResource(image_array.length);
}
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// create a new view
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_category, parent, false);
ViewHolder vh = new ViewHolder(v);
return vh;
}
// Replace the contents of a view (invoked by the layout manager)
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
if(holder instanceof ViewHolder) {
final Category c = items.get(position);
ViewHolder vItem = (ViewHolder) holder;
vItem.name.setText(Html.fromHtml(c.title));
vItem.post_count.setText(c.post_count + "");
Picasso.with(ctx).load(imageUri).into(vItem.imageView);
vItem.lyt_parent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (mOnItemClickListener != null) {
mOnItemClickListener.onItemClick(view, c, position);
}
}
});
}
}
public void setListData(List<Category> items){
this.items = items;
notifyDataSetChanged();
}
public void resetListData() {
this.items = new ArrayList<>();
notifyDataSetChanged();
}
// Return the size of your dataset (invoked by the layout manager)
#Override
public int getItemCount() {
return items.size();
}
}
This is my FragmentCategory.java for display data
public class FragmentCategory extends Fragment {
private View root_view, parent_view;
private RecyclerView recyclerView;
private SwipeRefreshLayout swipe_refresh;
private AdapterCategory mAdapter;
private Call<CallbackCategories> callbackCall = null;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
root_view = inflater.inflate(R.layout.fragment_category, null);
parent_view = getActivity().findViewById(R.id.main_content);
swipe_refresh = (SwipeRefreshLayout) root_view.findViewById(R.id.swipe_refresh_layout_category);
recyclerView = (RecyclerView) root_view.findViewById(R.id.recyclerViewCategory);
recyclerView.setLayoutManager(new GridLayoutManager(getActivity(),3));
recyclerView.setHasFixedSize(true);
//set data and list adapter
mAdapter = new AdapterCategory(getActivity(), new ArrayList<Category>());
recyclerView.setAdapter(mAdapter);
// on item list clicked
mAdapter.setOnItemClickListener(new AdapterCategory.OnItemClickListener() {
#Override
public void onItemClick(View v, Category obj, int position) {
ActivityCategoryDetails.navigate((ActivityMain) getActivity(), v.findViewById(R.id.lyt_parent), obj);
}
});
// on swipe list
swipe_refresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
mAdapter.resetListData();
requestAction();
}
});
requestAction();
return root_view;
}
private void displayApiResult(final List<Category> categories) {
mAdapter.setListData(categories);
swipeProgress(false);
if (categories.size() == 0) {
showNoItemView(true);
}
}
private void requestCategoriesApi() {
API api = RestAdapter.createAPI();
callbackCall = api.getAllCategories();
callbackCall.enqueue(new Callback<CallbackCategories>() {
#Override
public void onResponse(Call<CallbackCategories> call, Response<CallbackCategories> response) {
CallbackCategories resp = response.body();
if (resp != null && resp.status.equals("ok")) {
displayApiResult(resp.categories);
} else {
onFailRequest();
}
}
#Override
public void onFailure(Call<CallbackCategories> call, Throwable t) {
if (!call.isCanceled()) onFailRequest();
}
});
}
private void onFailRequest() {
swipeProgress(false);
if (NetworkCheck.isConnect(getActivity())) {
showFailedView(true, getString(R.string.failed_text));
} else {
showFailedView(true, getString(R.string.no_internet_text));
}
}
private void requestAction() {
showFailedView(false, "");
swipeProgress(true);
showNoItemView(false);
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
requestCategoriesApi();
}
}, Constant.DELAY_TIME);
}
#Override
public void onDestroy() {
super.onDestroy();
swipeProgress(false);
if(callbackCall != null && callbackCall.isExecuted()){
callbackCall.cancel();
}
}
private void showFailedView(boolean flag, String message) {
View lyt_failed = (View) root_view.findViewById(R.id.lyt_failed_category);
((TextView) root_view.findViewById(R.id.failed_message)).setText(message);
if (flag) {
recyclerView.setVisibility(View.GONE);
lyt_failed.setVisibility(View.VISIBLE);
} else {
recyclerView.setVisibility(View.VISIBLE);
lyt_failed.setVisibility(View.GONE);
}
((Button) root_view.findViewById(R.id.failed_retry)).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
requestAction();
}
});
}
private void showNoItemView(boolean show) {
View lyt_no_item = (View) root_view.findViewById(R.id.lyt_no_item_category);
((TextView) root_view.findViewById(R.id.no_item_message)).setText(R.string.no_category);
if (show) {
recyclerView.setVisibility(View.GONE);
lyt_no_item.setVisibility(View.VISIBLE);
} else {
recyclerView.setVisibility(View.VISIBLE);
lyt_no_item.setVisibility(View.GONE);
}
}
private void swipeProgress(final boolean show) {
if (!show) {
swipe_refresh.setRefreshing(show);
return;
}
swipe_refresh.post(new Runnable() {
#Override
public void run() {
swipe_refresh.setRefreshing(show);
}
});
}
And this is my ModeCategory.java
public class Category implements Serializable {
public int id = -1;
public String slug = "";
public String type = "";
public String url = "";
public String title = "";
public String title_plain = "";
public String content = "";
public String excerpt = "";
public String date = "";
public String modified = "";
public String description = "";
public int parent = -1;
public int post_count = -1;
public Author author;
public List<Category> categories = new ArrayList<>();
public List<Comment> comments = new ArrayList<>();
public List<Attachment> attachments = new ArrayList<>();
public CategoryRealm getObjectRealm(){
CategoryRealm c = new CategoryRealm();
c.id = id;
c.url = url;
c.slug = slug;
c.title = title;
c.description = description;
c.parent = parent;
c.post_count = post_count;
return c;
}
}

JSON parse android with Retrofit [duplicate]

This question already has an answer here:
Android - null object reference when iterating List
(1 answer)
Closed 5 years ago.
i want parse json with retrofit2 but my code dose not work
this web service is:(please check the webservice):
http://services.groupkt.com/country/search?text=
this is my model class:
public class Country {
#SerializedName("name")
#Expose
private String name;
#SerializedName("alpha2_code")
#Expose
private String alpha2Code;
#SerializedName("alpha3_code")
#Expose
private String alpha3Code;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAlpha2Code() {
return alpha2Code;
}
public void setAlpha2Code(String alpha2Code) {
this.alpha2Code = alpha2Code;
}
public String getAlpha3Code() {
return alpha3Code;
}
public void setAlpha3Code(String alpha3Code) {
this.alpha3Code = alpha3Code;
}
}
And:
public class CountryResponse {
#SerializedName("messages")
#Expose
private List<String> messages = null;
#SerializedName("result")
#Expose
private List<Country> countryList = null;
public List<String> getMessages() {
return messages;
}
public void setMessages(List<String> messages) {
this.messages = messages;
}
public List<Country> getCountryList() {
return countryList;
}
public void setCountryList(List<Country> countryList) {
this.countryList = countryList;
}
}
And:
public class Example {
#SerializedName("RestResponse")
#Expose
private CountryResponse restResponse;
public CountryResponse getRestResponse() {
return restResponse;
}
public void setRestResponse(CountryResponse restResponse) {
this.restResponse = restResponse;
}
}
And this is my interface class:
public interface APIInterface {
#GET("search?text=")
Call<Example> getCountries();
}
And i write 2 classes for return retrofit object:
public class APIClient {
private static Retrofit retrofit = null;
public static Retrofit getClient(String baseUrl) {
if (retrofit == null) {
retrofit = new Retrofit.Builder().baseUrl(baseUrl)
.addConverterFactory(GsonConverterFactory.create()).build();
}
return retrofit;
}
}
public class APIUtils {
public static final String BASE_URL =
"http://services.groupkt.com/country/";
public static APIInterface getSOService() {
return APIClient.getClient(BASE_URL).create(APIInterface.class);
}
}
My Adapter:
public class ResponseAdapter extends
RecyclerView.Adapter<ResponseAdapter.ViewHolder> {
private List<Example> mItems;
private Context mContext;
Example example;
CountryResponse countyResponse;
public ResponseAdapter(Context context, Example example) {
this.example = example;
mContext = context;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.item_list, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
Example example = mItems.get(position);
TextView textView = holder.name;
textView.setText(example.getRestResponse()
.getCountryList().get(position).getName());
TextView textView1 = holder.alpha;
textView1.setText(example.getRestResponse().
getCountryList().get(position).getAl
pha2Code());
TextView textView2 = holder.alpha2;
textView2.setText(example.getRestResponse().
getCountryList().get(position).getAl
pha3Code());
}
#Override
public int getItemCount() {
return mItems.size();
}
public void updateAnswers(CountryResponse countryRes) {
countyResponse = countryRes;
notifyDataSetChanged();
}
private Example getItem(int adapterPosition) {
return mItems.get(adapterPosition);
}
public interface PostItemListener {
void onPostClick(long id);
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView name, alpha, alpha2;
public ViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.name);
alpha = (TextView) itemView.findViewById(R.id.alpha);
alpha2 = (TextView) itemView.findViewById(R.id.alpha2);
}
}
}
And My Activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_response);
apiInterface= APIUtils.getSOService();
mRecyclerView= (RecyclerView) findViewById(R.id.my_recycler_view);
mAdapter=new ResponseAdapter(this,new Example());
RecyclerView.LayoutManager layoutManager = new
LinearLayoutManager(this);
mRecyclerView.setLayoutManager(layoutManager);
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setHasFixedSize(true);
loadAnswers();
}
private void loadAnswers() {
apiInterface.getCountries().enqueue(new Callback<Example>() {
#Override
public void onResponse(Call<Example> call, Response<Example>
response) {
mAdapter.updateAnswers(response.body().getRestResponse());
}
#Override
public void onFailure(Call<Example> call, Throwable t) {
}
});
}
when run a error showing that
'java.util.Iterator java.util.List.iterator()' on a null object reference

You have
#Override
public int getItemCount() {
return mItems.size();
}
public void updateAnswers(CountryResponse countryRes) {
countyResponse = countryRes;
notifyDataSetChanged();
}
Your List is not initialized in the first place. Secondly you need to populate your List with items. And your list must be Country list not of type Example
You need to change to
public void updateAnswers(CountryResponse countryRes) {
mItems.addAll(countryRes.getCountryList())
notifyDataSetChanged();
}
And also initialize the list
List<Country> mItems = new ArrayList();
// note its of type Country not of Example
Finally update your views accordingly in onBindViewHolder
textView.setText(mItems.get(position).getName());
textView1.setText(mItems.get(position).getAlpha2Code());
textView2.setText(mItems.get(position).getAlpha3Code());