Develop Reference

How to change TextView in Activity by delete button in RecyclerView?

When I add an item by button Scan Now, the public double sumCost value incrementes by the cost value in the AddItem method and then TextView(android:id="#+id/SumText") assigns this value. And How to decrease sumCost by the number that is in cost and set new text in TextView when pressing the Delete button? Thanks for any help
enter image description here
My full code:
MainActivity:
package com.example.testfirst;
...
public class MainActivity extends AppCompatActivity {
TextView sumText;
Button buttonAdd;
List<Contact> contacts = new LinkedList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_users);
buttonAdd = (Button) findViewById(R.id.scanBtn);
sumText = (TextView) findViewById(R.id.SumText);
buttonAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
AddItem("Tom", 2.45);
sumText.setText(Double.toString(sumCost));
}
});
}
public void AddItem(String name, double cost){
sumCost += cost;
RecyclerView rvContacts = (RecyclerView) findViewById(R.id.recyclerView);
ContactsAdapter adapter = new ContactsAdapter(contacts);
rvContacts.setAdapter(adapter);
rvContacts.setLayoutManager(new LinearLayoutManager(this));
contacts.add(new Contact(name,Double.toString(cost)));
}
public double sumCost = 0;
}
Contact(Model class):
...
public class Contact {
private String mName;
private String mCost;
public Contact(String name, String cost) {
mName = name;
mCost = cost;
}
public String getName() {
return mName;
}
public String getCost() {
return mCost;
}
}
ContactsAdapter:
...
public class ContactsAdapter extends RecyclerView.Adapter<ViewHolder>{
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
View contactView = inflater.inflate(R.layout.item_contact, parent, false);
return new ViewHolder(contactView).linkAdapter(this);
}
///////////////
#NonNull
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
Contact contact = mContacts.get(position);
TextView textViewId = holder.nameId;
textViewId.setText(contact.getName());
TextView textViewCost = holder.nameCost;
textViewCost.setText(contact.getCost());
}
#Override
public int getItemCount() {
return mContacts.size();
}
List<Contact> mContacts;
public ContactsAdapter(List<Contact> contacts) {
mContacts = contacts;
}
}
class ViewHolder extends RecyclerView.ViewHolder {
private ContactsAdapter adapter;
public TextView nameId;
public TextView nameCost;
public ViewHolder(#NonNull View itemView) {
super(itemView);
nameId = (TextView) itemView.findViewById(R.id.text);
nameCost = (TextView) itemView.findViewById(R.id.textCost);
itemView.findViewById(R.id.delete).setOnClickListener(view -> {
adapter.mContacts.remove(getAdapterPosition());
adapter.notifyItemRemoved(getAdapterPosition());
});
}
public ViewHolder linkAdapter(ContactsAdapter adapter){
this.adapter = adapter;
return this;
}
}
item_contact.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_margin="10dp"
app:cardCornerRadius="10dp"
app:cardElevation="5dp"
app:contentPadding="5dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:text="#string/app_name"
android:textSize="20sp" />
<TextView
android:id="#+id/textCost"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/text"
android:text="#string/app_name"
android:textSize="20sp" />
<Button
android:id="#+id/delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_marginTop="3dp"
android:layout_marginEnd="3dp"
android:text="Delete" />
</RelativeLayout>
</androidx.cardview.widget.CardView>
activity_users.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical"
android:padding="10dp">
<TextView
android:id="#+id/SumText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="0.00"
android:textSize="30sp"/>
<Button
android:id="#+id/scanBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Scan now"
android:textSize="30sp"
android:layout_gravity="center_horizontal"/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

One easy way to do that would be do add a "Decrementer" interface in the adapter that it can call to decrement the total cost, like this:
// Define the interface
public interface Decrementer {
void onDelete(double cost);
}
// Define an instance of the interface to hold
private final Decrementer mDecrementer;
// Pass in a decrementer at construction
public ContactsAdapter(List<Contact> contacts, Decrementer decr) {
mContacts = contacts;
mDecrementer = decr;
}
#NonNull
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
// get views and such ...
// Call the decrementer method when the button is clicked
// Could set this in onBindViewHolder, or pass the decrementer
// into the ViewHolder itself and use it there.
deleteButton.setOnClickListener(view -> {
int pos = holder.getAdapterPosition();
Contact c = mContacts.get(pos);
// add getCostAmount to return a double, or better yet, just
// store it as a Double instead of a string in Contact
mDecrementer.onDelete(c.getCostAmount());
mContacts.remove(pos);
notifyItemRemoved(pos);
});
}
and you would define the Decrementer when you create the adapter so it can access the Activity class members, like this:
ContactsAdapter adapter = new ContactsAdapter(contacts, new ContactsAdapter.Decrementer() {
#Override
public void onDelete(double cost) {
sumCost -= cost;
// change activity TextViews and such here too
sumText.setText(Double.toString(sumCost));
}
});
Side note: you don't need to create a whole new adapter every time you add an item, just add it to the contacts array and call an appropriate notifyDataSetChanged method on the existing adapter.
private ContactsAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_users);
//...
RecyclerView rvContacts = (RecyclerView) findViewById(R.id.recyclerView);
ContactsAdapter adapter = new ContactsAdapter(contacts);
rvContacts.setAdapter(adapter);
rvContacts.setLayoutManager(new LinearLayoutManager(this));
}
public void AddItem(String name, double cost){
sumCost += cost;
contacts.add(new Contact(name,Double.toString(cost)));
adapter.notifyDataSetChanged(); // or a less expensive notify call
}

Recyclerview and adapter doesn’t show

https://www.youtube.com/watch?v=M8sKwoVjqU0
i watched this video and i have done evertyhing same with.But there is a problem i guess myadapter class doesn't work because when i click button it comes just white screen as you see on the picture. i couldn't figure out where is the fault when i check the log no problem. but i just wanna take data from firebase to textview. but i can't get any result also at least it must see there just textview which is have text firstname but i can't see on my activity.i might be don't know the true page to will show
---this my myadapter.class----
public class Myadapter extends RecyclerView.Adapter<Myadapter.MyViewHolder> {
Context context;
ArrayList<User> list ;
public Myadapter(Context context, ArrayList<User> list) {
this.context = context;
this.list = list;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(context).inflate(R.layout.item,parent,false);
return new MyViewHolder(v) ;
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int position) {
User user =list.get(position);
holder.textView.setText(user.getTitle());
}
#Override
public int getItemCount() {
return list.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder{
TextView textView, TextView;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
TextView = itemView.findViewById(R.id.txtview);
textView=itemView.findViewById(R.id.title);
}
}
---this my userlist.class---
public class userlist extends AppCompatActivity {
RecyclerView recyclerView;
DatabaseReference database;
Myadapter myadapter;
ArrayList<User>list;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_userlist);
recyclerView=findViewById(R.id.userlist);
database = FirebaseDatabase.getInstance().getReference("users");
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
list = new ArrayList<>();
myadapter = new Myadapter(this,list);
recyclerView.setAdapter(myadapter);
database.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
for ( DataSnapshot dataSnapshot: snapshot.getChildren()){
User user=dataSnapshot.getValue(User.class);
list.add(user);
}
myadapter.notifyDataSetChanged();
}
---this my mainactivity.class---
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button1 = (Button) findViewById(R.id.button);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(MainActivity.this,userlist.class);
startActivity(i);
finish();}
});
}
}
{
"users" : {
"value1" : {
"title" : "reachthis"
}
}
}
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".userlist">
---activity_userlist---
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/userlist"
android:layout_width="409dp"
android:layout_height="729dp"
android:layout_marginStart="1dp"
android:layout_marginTop="1dp"
android:layout_marginEnd="1dp"
android:layout_marginBottom="1dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
</androidx.constraintlayout.widget.ConstraintLayout>```
---item.xml---
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
app:cardElevation="8dp"
>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"> </LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
>
<TextView
android:id="#+id/txtview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="first name"
android:textColor="#color/black"
android:textSize="26sp"
android:textStyle="bold"></TextView><TextView
android:id="#+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="first name"
android:textColor="#color/black"
android:textSize="20sp"
></TextView>
</LinearLayout>
</androidx.cardview.widget.CardView>

Add ArrayLIst to Recyclerview

I have an AlertDialog in it there used to be a ListView in which the contents of the ArrayList were displayed. For beauty, I decided to replace it with Recyclerview, Card and the problems started.
Items are added to ArrayList <String> mainListWord during the work and they should be included in the Recyclerview cards. The problem is that either the entire list falls into one card at once, or each next card contains the previous elements + 1. For example: the first card: 1 element, the second card: 2 elements, etc.
How to implement it so that when a new element is added to the array, it will be placed in its own card?
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<EditText
android:id="#+id/innerText"
android:layout_width="wrap_content"
android:layout_height="50dp"
android:layout_centerInParent="true"/>
<Button
android:id="#+id/press"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Press"
android:layout_below="#id/innerText"
android:layout_centerHorizontal="true"
android:onClick="openDialog"/>
</RelativeLayout>
recycler_item.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
app:cardCornerRadius="4dp"
android:layout_margin="4dp"
app:cardBackgroundColor="#color/colorCardBack">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="5dp"
android:background="#color/colorCard">
<ImageView
android:id="#+id/imageView_1"
android:layout_width="50dp"
android:layout_height="50dp"
android:padding="4dp" />
<TextView
android:id="#+id/textview_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Text_1"
android:textStyle="bold"
android:textColor="#android:color/black"
android:layout_centerInParent="true"
android:textSize="16sp"
android:layout_marginStart="5dp"
android:layout_toEndOf="#id/imageView_1"/>
</RelativeLayout>
</androidx.cardview.widget.CardView>
stats_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="50dp"
android:layout_margin="10dp"
android:background="#color/colorAccent"
android:scrollbars="vertical"
android:layout_above="#id/butClose"/>
<Button
android:id="#+id/butClose"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="5dp"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true"/>
</RelativeLayout>
MainActivity.java
public class MainActivity extends AppCompatActivity {
private EditText innerText;
private Button press, butClose;
private ArrayList<RecyclerViewItem> recyclerViewItem;
private ArrayList<String> mainListWord;
private AlertDialog OptionDialog;
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private RecyclerView.LayoutManager layoutManager;
#RequiresApi(api = Build.VERSION_CODES.O)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerViewItem = new ArrayList<>();
mainListWord = new ArrayList<>();
innerText = findViewById(R.id.innerText);
press = findViewById(R.id.butClose);
}
#RequiresApi(api = Build.VERSION_CODES.O)
public void makeRecyclerList(ArrayList<String> income){
String[] listWord_lenght = income.toArray(new String[0]);
String keyWord = (String.join("", listWord_lenght));
recyclerViewItem.add(new RecyclerViewItem(R.drawable.star, keyWord));
}
#RequiresApi(api = Build.VERSION_CODES.O)
public void openDialog(View v){
String word = innerText.getText().toString();
mainListWord.add(word);
makeRecyclerList(mainListWord);
Dialogus();
innerText.setText("");
}
public void Dialogus(){
LayoutInflater li = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = li.inflate(R.layout.stats_fragment, null, false);
OptionDialog = new AlertDialog.Builder(this).create();
OptionDialog.setTitle("TestInfo");
recyclerView = v.findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
adapter = new RecyclerViewAdapter(recyclerViewItem);
layoutManager = new LinearLayoutManager(this);
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(layoutManager);
butClose = v.findViewById(R.id.butClose);
OptionDialog.setView(v);
OptionDialog.setCancelable(true);
butClose.setBackgroundColor(Color.CYAN);
butClose.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
OptionDialog.dismiss();
}
});
OptionDialog.show();
}
}
RecyclerViewAdapter.java
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.RecyclerViewViewHolder> {
private ArrayList<RecyclerViewItem> arrayList;
public static class RecyclerViewViewHolder extends RecyclerView.ViewHolder {
public ImageView imageView_1;
public TextView textview_1;
public RecyclerViewViewHolder(#NonNull View itemView) {
super(itemView);
imageView_1 = itemView.findViewById(R.id.imageView_1);
textview_1 = itemView.findViewById(R.id.textview_1);
}
}
public RecyclerViewAdapter(ArrayList<RecyclerViewItem> arrayList){
this.arrayList = arrayList;
}
#NonNull
#Override
public RecyclerViewViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int viewType) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.recycler_item, viewGroup, false);
RecyclerViewViewHolder recyclerViewViewHolder= new RecyclerViewViewHolder(view);
return recyclerViewViewHolder;
}
#Override
public void onBindViewHolder(#NonNull RecyclerViewViewHolder recyclerViewViewHolder, int position) {
RecyclerViewItem recyclerViewItem = arrayList.get(position);
recyclerViewViewHolder.imageView_1.setImageResource(recyclerViewItem.getImageResource());
recyclerViewViewHolder.textview_1.setText(recyclerViewItem.getText_1());
}
#Override
public int getItemCount() {
return arrayList.size();
}
}
RecyclerViewItem.java
package freijer.app.one;
public class RecyclerViewItem {
private int imageResource;
private String text_1;
public int getImageResource() {
return imageResource;
}
public void setImageResource(int imageResource) {
this.imageResource = imageResource;
}
public String getText_1() {
return text_1;
}
public void setText_1(String text_1) {
this.text_1 = text_1;
}
public RecyclerViewItem(int imageResource, String text_1) {
this.imageResource = imageResource;
this.text_1 = text_1;
}
}

Can't display items in RecyclerView

I am having problems in displaying cards dynamically from a recycler view. Here's my code.
CardActivity.java
public class CardActivity extends AppCompatActivity {
CardAdapter mAdapter;
RecyclerView mRecyclerView;
ArrayList<CardModel> data = new ArrayList<>();
public static String IMGS[] = {
"https://scontent.fmnl4-2.fna.fbcdn.net/v/t1.0-9/12540788_486126334923939_641652950626105372_n.jpg?oh=520090fa887ded912ddb7086fc69fc93&oe=57A04969",
"https://scontent.fmnl4-2.fna.fbcdn.net/t31.0-8/12973436_521081094761796_6679453535369186441_o.jpg",
"https://scontent.fmnl4-2.fna.fbcdn.net/v/t1.0-9/12191632_465602330309673_5460380145671805117_n.jpg?oh=51811b46395fee6e4bdb5394e6725591&oe=57D35DC3",
"https://scontent.fmnl4-2.fna.fbcdn.net/v/t1.0-9/10628472_397420133794560_5446805358922772021_n.jpg?oh=f23ab8761e05b2a50d0d0c9dec4d365b&oe=57DBF1CC",
"https://scontent.fmnl4-2.fna.fbcdn.net/t31.0-8/10697227_314766035393304_2937143993369666506_o.jpg",
"https://scontent.fmnl4-2.fna.fbcdn.net/v/t1.0-9/13133194_10154674163886840_3764712620850385571_n.jpg?oh=252cedf88040188f12ce99c29f3dd47e&oe=57DD7474"
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_card);
for (int i = 0; i < IMGS.length; i++) {
CardModel cardModel = new CardModel();
cardModel.setTitle("Card Title: " + i);
cardModel.setDescription("This is a card description");
cardModel.setUrl(IMGS[i]);
data.add(cardModel);
}
Toolbar toolbar = (Toolbar) findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setTitle("Cards");
mRecyclerView = (RecyclerView) findViewById(R.id.cards);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(CardActivity.this);
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(linearLayoutManager);
mRecyclerView.setHasFixedSize(true);
mAdapter = new CardAdapter(CardActivity.this, data);
mRecyclerView.setAdapter(mAdapter);
}
public boolean onOptionsItemSelected(MenuItem item) {
onBackPressed();
return true;
}
}
CardModel.java
public class CardModel {
String url,title,description;
public CardModel() {
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
CardAdapter.java
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.CardHolder> {
private LayoutInflater inflater;
Context context;
List<CardModel> data = new ArrayList<>();
public CardAdapter(Context context, List<CardModel> data){
this.context = context;
this.data = data;
inflater = LayoutInflater.from(context);
}
#Override
public CardHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.card_layout,parent,false);
CardHolder cardHolder = new CardHolder(view);
return cardHolder;
}
#Override
public void onBindViewHolder(CardHolder holder, int position) {
holder.cardTitle.setText(data.get(position).getTitle());
holder.cardDescription.setText(data.get(position).getDescription());
Glide.with(context).load(data.get(position).getUrl())
.fitCenter()
.into(holder.cardImage);
}
#Override
public int getItemCount() {
return 0;
}
public static class CardHolder extends RecyclerView.ViewHolder {
ImageView cardImage;
TextView cardTitle;
TextView cardDescription;
public CardHolder(View cardView) {
super(cardView);
cardImage = (ImageView) cardView.findViewById(R.id.card_image);
cardTitle = (TextView) cardView.findViewById(R.id.card_title);
cardDescription = (TextView) cardView.findViewById(R.id.card_description);
}
}
}
activity_card.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.braudy.android.mesasixprofiler.CardActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<include layout="#layout/toolbar"/>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/cards"
android:layout_width="match_parent"
android:layout_height="fill_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
</FrameLayout>
card_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:background="#FFFFFF"
android:padding="10dp">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="250dp"
android:background="#ffffff">
<ImageView
android:layout_width="match_parent"
android:layout_height="150dp"
android:alpha=".7"
android:id="#+id/card_image"
android:background="#ffff66"
android:src="#drawable/img1"
android:scaleType="centerCrop"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Braudy"
android:paddingLeft="15dp"
android:textColor="#FFFFFF"
android:background="#707070"
android:alpha=".8"
android:textSize="25sp"
android:id="#+id/card_title"
android:layout_alignBottom="#+id/card_image"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<TextView
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:text="This is a description"
android:paddingTop="5dp"
android:paddingLeft="15dp"
android:textColor="#A9A9AF"
android:textSize="15sp"
android:id="#+id/card_description"
android:layout_below="#+id/card_image"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>

Change this
#Override
public int getItemCount() {
return 0;
}
to
#Override
public int getItemCount() {
return data.size();
}

change here-
#Override
public int getItemCount() {
return data.size();
}
You have to declare how much views you want to inflate in your view.

Populating a RecyclerView with CardView tied to an ArrayList

I am trying to create a swipeable CardView list inside a RecyclerView. However, none of the string values appear in the CardViews when I run the app.
This is my MainActivity class:
public class MainActivity extends Activity {
private CardViewAdapter mAdapter;
Button periodicbutton;
#Override
protected void onCreate(Bundle savedInstanceState) {
periodicbutton = (Button) findViewById(R.id.periodbutton);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String[] values = new String[] {"Quantitative Chemistry", "Atomic Structure", "Periodicity",
"Bonding", "Energetics","Kinetics","Equilibrium","Acids & Bases","Oxidation & Reduction","Organic Chemistry"};
final ArrayList<String> mItems = new ArrayList<>();
for (int i = 0; i < values.length; i++) {
mItems.add(values[i]);
}
OnItemTouchListener itemTouchListener = new OnItemTouchListener() {
#Override
public void onCardViewTap(View view, int position) {
Toast.makeText(MainActivity.this, "Swipe me", Toast.LENGTH_SHORT).show();
}
};
mAdapter = new CardViewAdapter(mItems, itemTouchListener);
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(mAdapter);
recyclerView.setHasFixedSize(false);
SwipeableRecyclerViewTouchListener swipeTouchListener =
new SwipeableRecyclerViewTouchListener(recyclerView,
new SwipeableRecyclerViewTouchListener.SwipeListener() {
#Override
public boolean canSwipe(int position) {
return true;
}
#Override
public void onDismissedBySwipeLeft(RecyclerView recyclerView, int[] reverseSortedPositions) {
for (int position : reverseSortedPositions) {
// Toast.makeText(MainActivity.this, mItems.get(position) + " swiped left", Toast.LENGTH_SHORT).show();
mItems.remove(position);
mAdapter.notifyItemRemoved(position);
}
mAdapter.notifyDataSetChanged();
}
#Override
public void onDismissedBySwipeRight(RecyclerView recyclerView, int[] reverseSortedPositions) {
for (int position : reverseSortedPositions) {
// Toast.makeText(MainActivity.this, mItems.get(position) + " swiped right", Toast.LENGTH_SHORT).show();
mItems.remove(position);
mAdapter.notifyItemRemoved(position);
}
mAdapter.notifyDataSetChanged();
}
});
recyclerView.addOnItemTouchListener(swipeTouchListener);
}
public interface OnItemTouchListener {
/**
* Callback invoked when the user Taps one of the RecyclerView items
*
* #param view the CardView touched
* #param position the index of the item touched in the RecyclerView
*/
void onCardViewTap(View view, int position);
}
public class CardViewAdapter extends RecyclerView.Adapter<CardViewAdapter.ViewHolder> {
private List<String> cards;
private OnItemTouchListener onItemTouchListener;
public CardViewAdapter(List<String> cards, OnItemTouchListener onItemTouchListener) {
this.cards = cards;
this.onItemTouchListener = onItemTouchListener;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.card_layout, viewGroup, false);
return new ViewHolder(v);
}
#Override
public void onBindViewHolder(ViewHolder viewHolder, int i) {
}
#Override
public int getItemCount() {
return cards == null ? 0 : cards.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public ViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onItemTouchListener.onCardViewTap(v, getPosition());
}
});
}
}
}
}
This is my activity_main.xml file:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/background"
android:orientation="vertical"
android:scrollbars="vertical">
<android.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="fill_parent"
android:layout_height="72dp"
android:background="#color/primary">
</android.widget.Toolbar>
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scrollbars="vertical" >
</android.support.v7.widget.RecyclerView>
</LinearLayout>
This is the card_view.xml file I'm trying to tie the string values to:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<android.support.v7.widget.CardView
android:id="#+id/quantutative"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground"
android:orientation="vertical"
card_view:cardCornerRadius="4dp">
<TextView
android:layout_width="fill_parent"
android:layout_height="54dp"
android:gravity="center_vertical"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:textColor="#color/card_text"
android:textSize="36sp"
/>
</android.support.v7.widget.CardView>
</LinearLayout>