i'm new to android programming, i have a issue with a recyclerview ( i'm reading an android programming book and practice ) : it's showing only one item although i passed a list of 100 items
here's the code of the class:
package com.training.criminalintent;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;
public class CrimeListFragment extends Fragment {
private RecyclerView mCrimeRecyclerView;
private CrimeAdapter mAdapter;
#Override
public View onCreateView(LayoutInflater inflater,ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_crime_list, container, false);
mCrimeRecyclerView = (RecyclerView) view
.findViewById(R.id.crime_recycler_view);
mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
updateUI();
return view;
}
private class CrimeHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
private Crime mCrime;
private TextView mTitleTextView;
private TextView mDateTextView;
private CheckBox mSolvedCheckBox;
public CrimeHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
mTitleTextView = (TextView)
itemView.findViewById(R.id.list_item_crime_title_text_view);
mDateTextView = (TextView)
itemView.findViewById(R.id.list_item_crime_date_text_view);
mSolvedCheckBox = (CheckBox)
itemView.findViewById(R.id.list_item_crime_solved_check_box);
}
public void bindCrime(Crime crime) {
mCrime = crime;
mTitleTextView.setText(mCrime.getTitle());
mDateTextView.setText(mCrime.getDate().toString());
mSolvedCheckBox.setChecked(mCrime.isSolved());
}
#Override
public void onClick(View v) {
Intent intent = new Intent(getActivity(), CrimeActivity.class);
startActivity(intent);
}
}
private class CrimeAdapter extends RecyclerView.Adapter<CrimeHolder> {
private List<Crime> mCrimes;
public CrimeAdapter(List<Crime> crimes) {
mCrimes = crimes;
}
#Override
public int getItemCount() {
return mCrimes.size();
}
#Override
public CrimeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
View view = layoutInflater
.inflate(R.layout.list_item_crime, parent, false);
return new CrimeHolder(view);
}
#Override
public void onBindViewHolder(CrimeHolder holder, int position) {
Crime crime = mCrimes.get(position);
holder.bindCrime(crime);
}
}
private void updateUI() {
CrimeLab crimeLab = CrimeLab.get(getActivity());
List<Crime> crimes = crimeLab.getCrimes();
mAdapter = new CrimeAdapter(crimes);
mCrimeRecyclerView.setAdapter(mAdapter);
}
}
Thanks in advance for you help,
The book somehow made a mistake.
The actual input should be android:layout_height="wrap_content"
Thanks yo your answer. Indeed my mistake was the recyclerView attribute android:layout_height.
I put match_parent instead of wrap_content
Related
I am new, and I am making an app that displays data in a cardView within a recyclerView in android studio. I am trying to be able to delete the data that is displayed on the cardView. The cardView and data gets deleted as it should, but once I go back to the activity holding the cardView and recyclerView, it's all still there. Does anyone know why this is happening? I'll post my code below
ReminderDBHelper:
package com.example.lasttry;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.MyViewHolder> {
private Context context;
private ArrayList reminder_id, reminder_title, reminder_location, reminder_medication;
reminderDBHelper mydb;
Button reminderDelete;
CustomAdapter(Context context,
ArrayList reminder_id,
ArrayList reminder_title,
ArrayList reminder_location,
ArrayList reminder_medication) {
this.context = context;
this.reminder_id = reminder_id;
this.reminder_title = reminder_title;
this.reminder_location = reminder_location;
this.reminder_medication = reminder_medication;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.my_row, parent, false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, final int position) {
holder.reminder_id.setText(String.valueOf(reminder_id.get(position)));
holder.reminder_title.setText(String.valueOf(reminder_title.get(position)));
holder.reminder_location.setText(String.valueOf(reminder_location.get(position)));
holder.reminder_medication.setText(String.valueOf(reminder_medication.get(position)));
holder.reminderDelete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mydb = new reminderDBHelper(context);
String id = String.valueOf(reminder_id);
mydb.deleteData(id);
reminder_id.remove(holder.getAdapterPosition());
notifyItemRemoved(holder.getLayoutPosition());
}
});
holder.mainLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(context, UpdateActivity.class);
intent.putExtra("id", String.valueOf(reminder_id.get(holder.getAdapterPosition())));
intent.putExtra("title", String.valueOf(reminder_title.get(holder.getAdapterPosition())));
intent.putExtra("location", String.valueOf(reminder_location.get(holder.getAdapterPosition())));
intent.putExtra("medication", String.valueOf(reminder_medication.get(holder.getAdapterPosition())));
context.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return reminder_id.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView reminder_id, reminder_title, reminder_location, reminder_medication;
Button reminderDelete;
LinearLayout mainLayout;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
reminderDelete = itemView.findViewById(R.id.reminder_delete);
reminder_id = itemView.findViewById(R.id.reminder_id);
reminder_title = itemView.findViewById(R.id.reminder_title);
reminder_location = itemView.findViewById(R.id.reminder_location);
reminder_medication = itemView.findViewById(R.id.reminder_medication);
mainLayout = itemView.findViewById(R.id.mainLayout);
}
}
}
CustomAdapter:
package com.example.lasttry;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.MyViewHolder> {
private Context context;
private ArrayList reminder_id, reminder_title, reminder_location, reminder_medication;
reminderDBHelper mydb;
Button reminderDelete;
CustomAdapter(Context context,
ArrayList reminder_id,
ArrayList reminder_title,
ArrayList reminder_location,
ArrayList reminder_medication) {
this.context = context;
this.reminder_id = reminder_id;
this.reminder_title = reminder_title;
this.reminder_location = reminder_location;
this.reminder_medication = reminder_medication;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.my_row, parent, false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, final int position) {
holder.reminder_id.setText(String.valueOf(reminder_id.get(position)));
holder.reminder_title.setText(String.valueOf(reminder_title.get(position)));
holder.reminder_location.setText(String.valueOf(reminder_location.get(position)));
holder.reminder_medication.setText(String.valueOf(reminder_medication.get(position)));
holder.reminderDelete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mydb = new reminderDBHelper(context);
String id = String.valueOf(reminder_id);
mydb.deleteData(id);
reminder_id.remove(holder.getAdapterPosition());
notifyItemRemoved(holder.getLayoutPosition());
}
});
holder.mainLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(context, UpdateActivity.class);
intent.putExtra("id", String.valueOf(reminder_id.get(holder.getAdapterPosition())));
intent.putExtra("title", String.valueOf(reminder_title.get(holder.getAdapterPosition())));
intent.putExtra("location", String.valueOf(reminder_location.get(holder.getAdapterPosition())));
intent.putExtra("medication", String.valueOf(reminder_medication.get(holder.getAdapterPosition())));
context.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return reminder_id.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView reminder_id, reminder_title, reminder_location, reminder_medication;
Button reminderDelete;
LinearLayout mainLayout;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
reminderDelete = itemView.findViewById(R.id.reminder_delete);
reminder_id = itemView.findViewById(R.id.reminder_id);
reminder_title = itemView.findViewById(R.id.reminder_title);
reminder_location = itemView.findViewById(R.id.reminder_location);
reminder_medication = itemView.findViewById(R.id.reminder_medication);
mainLayout = itemView.findViewById(R.id.mainLayout);
}
}
}
I have searched stackOverflow and reddit, but nothing seems to work. I have tried making the array array list instead.
I want the app to open a page when the user taps on an item and pass some extra information to that intent. That's it. I tried about 7 - 10 onclickListener types but I didn't solve anything. I am posting my adapter class with the latest implementation ( that doesn't work ). Json works and the Recyclerview loads data and images from url with no problems.
package byDragosT.myapplication;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.GridLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.recyclerview.widget.RecyclerView;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
public class RecipeApiAdapter extends RecyclerView.Adapter<RecipeApiAdapter.RecipeViewHolder> {
private ArrayList<RecipeItem> recipeItems;
private Context context;
public RecipeApiAdapter(ArrayList<RecipeItem> recipeItems, Context context){
this.recipeItems = recipeItems;
this.context = context;
}
#NonNull
#Override //// Mare grija ce layout pui aici - sfat pentru viitor - mi-a luat 4 ore sa gasesc eroarea
public RecipeViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recipe_item_in_recyclerview_api, parent, false);
return new RecipeViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull RecipeViewHolder holder, int position) {
final RecipeItem recipeItem = recipeItems.get(position);
holder.title.setText(recipeItem.getMnameRecipe());
holder.description.setText(recipeItem.getMdescribeRecipe());
Picasso.get().load(recipeItem.getItemPictureUrl())
.into(holder.jpegRecipe);
System.out.println("image with title: " + holder.title.getText() + "was added in theory");
}
#Override
public int getItemCount() {
return recipeItems.size();
}
public static class RecipeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public ImageView jpegRecipe;
public TextView title;
public TextView description;
public RelativeLayout containerView;
public RecyclerView mRecyclerView;
RecipeViewHolder(View view){
super(view);
jpegRecipe = view.findViewById(R.id.picture);
title = view.findViewById(R.id.recipe_name);
description = view.findViewById(R.id.ingredients_list);
containerView = view.findViewById(R.id.recipe_item_container); // vezi aici
mRecyclerView = view.findViewById(R.id.recyclerView);
}
#Override
public void onClick(View v) {
int itemPosition = mRecyclerView.getChildLayoutPosition(v);
RecipeItem current = recipeItems.get(itemPosition);
Intent intent = new Intent(v.getContext(), RecipeDetailsActivity.class);
intent.putExtra("name", current.getMnameRecipe());
v.getContext().startActivity(intent);
}
}
}
Try adding view.setOnClickListener(this);
RecipeViewHolder(View view){
super(view);
view.setOnClickListener(this);
.....
}
RecyclerView Code:OnClickListener
package com.example.cardview;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
public class ArrayAdapter extends RecyclerView.Adapter<ArrayAdapter.ViewHolder> {
private String[] divisionName;
ArrayAdapter(String[] phoneNumebr) {
this.divisionName = phoneNumebr;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from( context );
View v = inflater.inflate( R.layout.element, parent, false );
return new ViewHolder( v );
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, final int position) {
holder.cNumbers.setText(divisionName[position] );
holder.itemView.setOnClickListener( new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(this,divisionName[position],Toast.LENGTH_LONG).show();
}
} );
}
#Override
public int getItemCount() {
return divisionName.length;
}
static class ViewHolder extends RecyclerView.ViewHolder{
TextView cNumbers;
ViewHolder(#NonNull View itemView) {
super( itemView );
this.cNumbers = itemView.findViewById( R.id.cNumbers );
}
How to add OnClickListener in recyclerView according to the item position
How to add OnClickListener in recyclerView according to the item
position
To add OnClickListener to RecyclerView items, you achieve that within your custom RecyclerView.ViewHolder class, by setting .onClickListener() to the View passed into the ViewHolder constructor
snippet from your code:
static class ViewHolder extends RecyclerView.ViewHolder{
TextView cNumbers;
ViewHolder(#NonNull View itemView) {
super( itemView );
this.cNumbers = itemView.findViewById( R.id.cNumbers );
listItem.setOnClickListener(){
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "Click on position number: " + getAdapterPosition(), Toast.LENGTH_SHORT).show();
Toast.makeText(v.getContext(), divisionName[getAdapterPosition()],Toast.LENGTH_LONG).show();
}
}
}
}
Just Change Your Toast.
Toast.makeText(holder.itemView.getContext(),"You clicked "+divisionName[position],Toast.LENGTH_SHORT).show();
I can't put my textView in the method onBindViewHolder from the inner class Item, I made it public and final and is still cannot resolve it, I tried many examples and it's the same problem.
package com.example.recyclerview;
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;
public class Adapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
Context context;
String [] items;
public Adapter(Context context, String[] items){
this.context = context;
this.items = items;
}
#NonNull
#Override
public RecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
LayoutInflater inflater = LayoutInflater.from(context);
View row = inflater.inflate(R.layout.custom_row, viewGroup, false);
Item item = new Item(row);
return item;
}
#Override
public void onBindViewHolder(#NonNull RecyclerView.ViewHolder viewHolder, int i) {
String mCurrent = items[i];
viewHolder.textView.setText(mCurrent); // error here textView cannot resolve
}
#Override
public int getItemCount() {
return items.length;
}
public class Item extends RecyclerView.ViewHolder {
public final TextView textView;
public Item(#NonNull View itemView) {
super(itemView);
textView = (TextView) itemView.findViewById(R.id.item);
}
}
}
You should correct generic type of the adapter: use Adapter.Item instead of RecyclerView.ViewHolder
public class Adapter extends RecyclerView.Adapter<Adapter.Item>
and then update signature of onCreateViewHolder and onBindViewHolder methods
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 4 years ago.
I'm getting error in crimeholder class , which states
'java.lang.NullPointerException:Attempt to invoke virtual method
'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference'
I copied pasted most of the code from the book which I bought from amazon.
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
public class CrimeListFragment extends Fragment {
private RecyclerView mCrimeRecyclerView;
private CrimeAdapter mAdapter;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_crime_list, container, false);
mCrimeRecyclerView = (RecyclerView) view
.findViewById(R.id.crime_recycler_view);
mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
updateUI();
return view;
}
private void updateUI() {
CrimeLab crimeLab = CrimeLab.get(getActivity());
List<Crime> crimes = crimeLab.getCrimes();
mAdapter = new CrimeAdapter(crimes);
mCrimeRecyclerView.setAdapter(mAdapter);
}
//
private class CrimeHolder extends RecyclerView.ViewHolder {
private Crime mCrime;
private TextView mTitleTextView;
private TextView mDateTextView;
public CrimeHolder(LayoutInflater inflater, ViewGroup parent) {
super(inflater.inflate(R.layout.list_item_crime, parent, false));
mTitleTextView = (TextView) itemView.findViewById(R.id.crime_title);
mDateTextView = (TextView) itemView.findViewById(R.id.crime_date);
}
public void bind(Crime crime) {
mCrime = crime;
mTitleTextView.setText(mCrime.getmTitle());
mDateTextView.setText(mCrime.getmDate().toString());
}
}
private class CrimeAdapter extends RecyclerView.Adapter<CrimeHolder> {
private List<Crime> mCrimes;
public CrimeAdapter(List<Crime> crimes) {
mCrimes = crimes;
}
#Override
public CrimeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
return new CrimeHolder(layoutInflater, parent);
}
#Override
public void onBindViewHolder(CrimeHolder holder, int position) {
Crime crime = mCrimes.get(position);
holder.bind(crime);
}
#Override
public int getItemCount() {
return mCrimes.size();
}
}
}
//
import android.support.v4.app.Fragment;
public class CrimeActivity extends SingleFragmentActivity {
#Override
protected Fragment createFragment() {
return new CrimeFragment();
}
}
//
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.EditText;
public class CrimeFragment extends Fragment {
private Crime mCrime;
private EditText mTitleField;
private Button mDateButton;
public CheckBox mSolvedCheckBox;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mCrime = new Crime();
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState)
{
View v = inflater.inflate(R.layout.fragment_crime, container, false);
mTitleField = (EditText) v.findViewById(R.id.crime_title);
mTitleField.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count)
{
mCrime.setmTitle(s.toString());
}
#Override
public void afterTextChanged(Editable s) {
}
});
mDateButton = (Button) v.findViewById(R.id.crime_date);
mDateButton.setText(mCrime.getmDate().toString());
mDateButton.setEnabled(false);
mSolvedCheckBox = (CheckBox)v.findViewById(R.id.crime_solved);
mSolvedCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener(){
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mCrime.setmSolved(isChecked);
}
});
return v;
}
}
//
import android.content.Context;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
public class CrimeLab {
private static CrimeLab sCrimeLab;
private List<Crime> mCrimes;
public static CrimeLab get(Context context) {
if (sCrimeLab == null) {
sCrimeLab = new CrimeLab(context);
}
return sCrimeLab;
}
private CrimeLab(Context context) {
mCrimes = new ArrayList<>();
for (int i = 0; i < 100; i++) {
Crime crime = new Crime();
crime.setmTitle("Crime #" + i);
crime.setmSolved(i % 2 == 0); // Every other one
mCrimes.add(crime);
}
}
public List<Crime> getCrimes() {
return mCrimes;
}
public Crime getCrime(UUID id) {
for (Crime crime : mCrimes) {
if (crime.getmId().equals(id)) {
return crime;
}
}
return null;
}
}
//
import android.support.v4.app.Fragment;
public class CrimeListActivity extends SingleFragmentActivity {
#Override
protected Fragment createFragment() {
return new CrimeListFragment();
}
}
//
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
public class CrimeListFragment extends Fragment {
private RecyclerView mCrimeRecyclerView;
private CrimeAdapter mAdapter;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_crime_list, container, false);
mCrimeRecyclerView = (RecyclerView) view
.findViewById(R.id.crime_recycler_view);
mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
updateUI();
return view;
}
private void updateUI() {
CrimeLab crimeLab = CrimeLab.get(getActivity());
List<Crime> crimes = crimeLab.getCrimes();
mAdapter = new CrimeAdapter(crimes);
mCrimeRecyclerView.setAdapter(mAdapter);
}
private class CrimeHolder extends RecyclerView.ViewHolder {
private Crime mCrime;
private TextView mTitleTextView;
private TextView mDateTextView;
public CrimeHolder(LayoutInflater inflater, ViewGroup parent) {
super(inflater.inflate(R.layout.list_item_crime, parent, false));
mTitleTextView = (TextView) itemView.findViewById(R.id.crime_title);
mDateTextView = (TextView) itemView.findViewById(R.id.crime_date);
}
public void bind(Crime crime) {
mCrime = crime;
mTitleTextView.setText(mCrime.getmTitle());
mDateTextView.setText(mCrime.getmDate().toString());
}
}
private class CrimeAdapter extends RecyclerView.Adapter<CrimeHolder> {
private List<Crime> mCrimes;
public CrimeAdapter(List<Crime> crimes) {
mCrimes = crimes;
}
#Override
public CrimeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
return new CrimeHolder(layoutInflater, parent);
}
#Override
public void onBindViewHolder(CrimeHolder holder, int position) {
Crime crime = mCrimes.get(position);
holder.bind(crime);
}
#Override
public int getItemCount() {
return mCrimes.size();
}
}
}
//
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;
public abstract class SingleFragmentActivity extends AppCompatActivity {
protected abstract Fragment createFragment();
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fragment);
FragmentManager fm = getSupportFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.fragment_container);
if (fragment == null) {
fragment = createFragment();
fm.beginTransaction()
.add(R.id.fragment_container, fragment)
.commit();
}
}
}
//activity_fragment.xmml
FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/fragment_container"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".CrimeActivity">
</FrameLayout>
//fragment_crime.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="16dp"
android:orientation="vertical">
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/crime_title_label"/>
<EditText
android:id="#+id/crime_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/crime_title_hint" />
<TextView
style="?android:listSeparatorTextViewStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/crime_details_label"/>
<Button
android:id="#+id/crime_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<CheckBox
android:id="#+id/crime_solved"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/crime_solved_label"/>
</LinearLayout>
//
//fragment_crime_list.xml
<android.support.v7.widget.RecyclerView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/crime_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
//list_item_crime.xml
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="crime_title"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/crime_date"
android:text="crime_date"/>
Try as follows
In your CrimeAdapter under onCreateViewHolder, Pass views to CrimeHolder
class
#NonNull
#Override
public CrimeHolder onCreateViewHolder(#NonNull ViewGroup viewGroup,int i){
LayoutInflater layoutInflater = LayoutInflater.from(context);
View view = layoutInflater.inflate( R.layout.list_item_crime, viewGroup, false );
// here pass view as a constructor
return new CrimeHolder(view);
}
In your CrimeHolder, set to superclass and retrieve other property as follows
private class CrimeHolder extends RecyclerView.ViewHolder{
private TextView mTitleTextView;
private TextView mDateTextView;
CrimeHolder(View view){
super(view);
mTitleTextView = view.findViewById(R.id.textView);
mDateTextView = view.findViewById(R.id.textView2);
}
}
You are not finding the views properly, you are calling super() and in the same time trying to find the textviews from itemView which I don't where are you initialing it. Do the following:
Replace
mTitleTextView = (TextView) itemView.findViewById(R.id.crime_title);
mDateTextView = (TextView) itemView.findViewById(R.id.crime_date);
with
mTitleTextView = (TextView) findViewById(R.id.crime_title);
mDateTextView = (TextView) findViewById(R.id.crime_date);
OR
Replace
super(inflater.inflate(R.layout.list_item_crime, parent, false));
with
itemView = (ViewGroup) inflater.inflate(R.layout.list_item_crime, parent, false);