Scenario:
I am trying to create a RecyclerView which will show a few different kinds of item (food, book, recipes) in one list. The data will be fetched from the server with the help of retrofit when the user types in some keyword into the search bar. So, I have an activity with a search bar, another to show the data in a recycler view.
What is have done so far: 1. Fetch data from server with the help of recycler view on search. 2. Send the data (in serializable) form from the search activity to display activity. 3. Create a recycler view with multiple view adapter (With the help of some tutorials listed below).
links:
Some related Projects:
Understanding
What i have understood so far is that for showing multiple types of items in the recycler view, we need to create an abstract view holder and individual view holders for each object. They must also have their corresponding layout and they layouts are inflated dynamically into the recycler view holder.
Problem:
- Trying to set adapter to my recycler view adapter gives error.
- The problem Im facing is that I cannot seem to bind the data that I received from the server with the corresponding view holder.
Code:
I will leave out the activity where I am fetching data because its working.
SearhResultActivity (this activity receives the data from SearchActivity and is supposed to show the recycler view with the data)
package com.example.naisse.Activity;
import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.support.v7.widget.RecyclerView;
import android.widget.FrameLayout;
import com.example.naisse.AdapterAndClass.ResultAdaptar;
import com.example.naisse.AdapterAndClass.SearchRecyclerAdapter;
import com.example.naisse.Api.Model.Search.Article;
import com.example.naisse.Api.Model.Search.Food;
import com.example.naisse.Api.Model.Search.Hadith;
import com.example.naisse.Api.Model.Search.Manuscript;
import com.example.naisse.Api.Model.Search.Quran;
import com.example.naisse.Fragment.SearchTabFragment;
import com.example.naisse.R;
import java.util.ArrayList;
import java.util.List;
import butterknife.BindView;
public class SearchResultActivity extends HomeActivity {
private static final String TAG = "SearchResultActivity";
@BindView(R.id.search_result_recycler)
RecyclerView recyclerView;
private SearchRecyclerAdapter searchRecyclerAdapter;
private List<String> dataList;
protected FrameLayout frames;
private FragmentManager mFragmentManager;
private ResultAdaptar resultAdaptar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_result);
frames = findViewById(R.id.search_bar_holder);
mFragmentManager = (this).getSupportFragmentManager();
mFragmentManager.beginTransaction().add(R.id.search_bar_holder, new SearchTabFragment()).commit();
Food foodData = new Food();
ArrayList<Book> getBookArray = new ArrayList<>();
ArrayList<Recipe> getRecipe = new ArrayList<>();
foodData = (Food) getIntent().getSerializableExtra("foodDetails");
getBookArray = (ArrayList<Book>) getIntent().getSerializableExtra("bookList");
getRecipe = (ArrayList<Recipe>) getIntent().getSerializableExtra("recipeList");
/*There is something wrong here, it says "Attempt to invoke virtual method on a null object reference" for searchRecyclerAdapter*/
searchRecyclerAdapter = new SearchRecyclerAdapter(this);
recyclerView.setAdapter(searchRecyclerAdapter);
}
}
SearchRecyclerAdapter (This adapter holders the codes for declaration and connecting all the viewHolders to the abstract viewHolder with connects to the recycler view)
package com.example.naisse.AdapterAndClass;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.example.naisse.Api.Model.Search.Food;
import com.example.naisse.Api.Model.Search.Quran;
import com.example.naisse.R;
import java.util.ArrayList;
import java.util.List;
import butterknife.BindView;
import butterknife.ButterKnife;
public class SearchRecyclerAdapter extends RecyclerView.Adapter<SearchRecyclerAdapter.AbstractViewHolder>{
private static final String TAG = "SearchRecyclerAdapter";
public static final int TYPE_FOOD = 0;
public static final int TYPE_BOOK = 1;
private Context context;
private List<Object> data;
/*I belive im missing something here*/
public SearchRecyclerAdapter(Context context){
this.context = context;
}
public void add(List searchData){
if(data == null){
data = new ArrayList<>();
}
data.clear();
data.addAll(searchData);
notifyDataSetChanged();
}
@Override
public AbstractViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
switch (i){
case TYPE_FOOD:{
/*search_result_fragment is the xml layout for food adapter*/
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.search_result_fragment, viewGroup, false);
return new FoodViewAdapter(view);
}
case TYPE_BOOK:{
/*search_result_fragment is the xml layout for book adapter*/
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.viewholder_book, viewGroup, false);
return new BooksViewAdapter(view);
}
default:
throw new IllegalArgumentException("Invalid view type");
}
}
@Override
public void onBindViewHolder(AbstractViewHolder abstractViewHolder, int i) {
Object object = data.get(i);
abstractViewHolder.bind(object);
}
@Override
public int getItemViewType(int i){
Object object = data.get(i);
if (object instanceof Food){
return TYPE_FOOD;
}else if (object instanceof Book){
return TYPE_BOOK;
}
throw new IllegalArgumentException("Invalid position");
}
@Override
public int getItemCount() {
return data == null ? 0 : data.size();
}
public abstract class AbstractViewHolder<T> extends RecyclerView.ViewHolder{
public AbstractViewHolder(@NonNull View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
public abstract void bind(T type);
}
public class FoodViewAdapter extends AbstractViewHolder<Food> {
@BindView(R.id.result_food_title)
TextView foodTitle;
@BindView(R.id.result_food_content)
TextView content;
private FoodViewAdapter(View itemView){
super(itemView);
}
@Override
public void bind(Food type) {
foodTitle.setText("Food");
content.setText("title");
}
}
public class BooksViewAdapter extends AbstractViewHolder<Book> {
@BindView(R.id.result_book_title)
TextView bookTitle;
@BindView(R.id.result_book_content)
TextView content;
private BooksViewAdapter(View itemView){
super(itemView);
}
@Override
public void bind(Book type) {
bookTitle.setText("title");
content.setText("Text");
}
}
}
Question:
How do i set the adapter and how do I bind my data to the corresponding views?
P.S Please let me know if you want to see some other classes or XML layouts.
Logcat
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.naisse, PID: 12570
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.naisse/com.example.naisse.Activity.SearchResultActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setAdapter(android.support.v7.widget.RecyclerView$Adapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setAdapter(android.support.v7.widget.RecyclerView$Adapter)' on a null object reference
at com.example.naisse.Activity.SearchResultActivity.onCreate(SearchResultActivity.java:67)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
