Develop Reference

How do I set variables to true/false from a Listview of Checkboxes?

I created a listview with a custom adapter that allows me to have a list of items with checkboxes next to each item.
So I would like to look at the checkbox for the corresponding item in the list and see if it is checked and if it is, then set the value of boolean whiskey = false to true and so on for the other booleans.
It is very possible I have code in the wrong class or xml file, I've been trying to piece together things I've found on the internet. I'm new to android studio so its proving very difficult. I do have about a years worth of java experience though. I have all my code written in a working program on Eclipse, I am just having a hell of a time figuring out how to implement it into a working app.
Thanks in advance.
customAdapter.java
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;
import java.util.ArrayList;
public class customAdapter extends BaseAdapter {
private ArrayList<String> list = new ArrayList<String>();
private Context context;
public customAdapter(ArrayList<String> list, Context context) {
this.list = list;
this.context = context;
}
#Override
public int getCount() {
return list.size();
}
#Override
public Object getItem(int pos) {
return list.get(pos);
}
public void setChecked(boolean isChecked){
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView;
if (view == null) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.activity2_listview, null);
}
//Handle TextView and display string from your list
TextView label = (TextView)view.findViewById(R.id.label);
label.setText(list.get(position));
//Handle buttons and add onClickListeners
CheckBox callchkbox = (CheckBox) view.findViewById(R.id.cb);
callchkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
//update isChecked value to model class of list at current position
list.get(position).setChecked(isChecked);
}
});
return view;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
Main2Activity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import android.widget.CheckBox;
public class Main2Activity extends AppCompatActivity {
boolean Whiskey, Bourbon, Rum, Gin, Vodka, Tequila = false;
String [] userIngredients = {"Whiskey", "Bourbon", "Rum", "Gin", "Vodka", "Tequila", "Club Soda", "Lemon-Lime Soda",
"Ginger ale", "Cola", "Still mineral water", "Tonic Water", "Orange Juice", "Cranberry Juice", "Grapefruit Juice",
"Tomato Juice", "Cream or Half and Half", "Milk", "Ginger Beer", "PineApple Juice", "Lemons", "Limes", "Oranges"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
ListView listView = (ListView) findViewById(R.id.userIngredients);
ArrayList<String> list = new ArrayList<String>(Arrays.asList(userIngredients));
listView.setAdapter(new customAdapter(list, Main2Activity.this));
}
}
activity_main2.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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=".Main2Activity"
android:id="#+id/linearLayout">
<ListView
android:layout_width="419dp"
android:layout_height="558dp"
android:id="#+id/userIngredients"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView2"
tools:layout_conversion_absoluteHeight="731dp"
tools:layout_conversion_absoluteWidth="411dp" />
<TextView
android:id="#+id/textView2"
android:layout_width="374dp"
android:layout_height="60dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:text="Check Your Ingredients"
android:textSize="24sp"
app:fontFamily="#font/cinzel"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
activity2_listview.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/label"
android:layout_width="323dp"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:text="ingredient"
android:textSize="20sp" />
<CheckBox
android:id="#+id/cb"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>

i think you can do it with a BaseAdapter as well, but i suggest to use a RecyclerView instead.
I used support-v4 and recyclerview-v7 libs as following:
(Make sure that you are not developing AndroidX - check your gradle.properties of the entire project. It is very similar but uses other libraries though.)
build.gradle
android {
compileSdkVersion 28
buildToolsVersion '28.0.3'
...
dependencies {
implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:support-v4:28.0.0'
implementation 'com.android.support:design:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
implementation 'com.android.support:recyclerview-v7:28.0.0'
...
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.widget.RelativeLayout
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">
<TextView
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Check Your Ingredients"
android:textAlignment="center" />
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_chooser"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" >
</android.support.v7.widget.RecyclerView>
</android.widget.RelativeLayout>
In the activity2_listview you might want to do more design to the xml. It looks very basic now.
activity2_listview.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/listviewtextlabel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:text="ingredient"
android:textSize="20sp" />
<CheckBox
android:id="#+id/listviewcheckbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
In the main class we implement a callback-listener for our custom onItemAction function. We pass the listener with adapter.setActionListener(this); and add the adapter to the RecyclerViewer.
MainActivity.java
public class MainActivity extends AppCompatActivity implements CustomAdapter.ItemActionListener {
boolean Whiskey, Bourbon, Rum, Gin, Vodka, Tequila = false;
String [] userIngredients = {"Whiskey", "Bourbon", "Rum", "Gin", "Vodka", "Tequila", "Club Soda", "Lemon-Lime Soda",
"Ginger ale", "Cola", "Still mineral water", "Tonic Water", "Orange Juice", "Cranberry Juice", "Grapefruit Juice",
"Tomato Juice", "Cream or Half and Half", "Milk", "Ginger Beer", "PineApple Juice", "Lemons", "Limes", "Oranges"};
CustomAdapter adapter;
RecyclerView.LayoutManager layoutManager;
RecyclerView recyclerListView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
recyclerListView = (RecyclerView) findViewById(R.id.recycler_chooser);
ArrayList<String> list = new ArrayList<>();
list.addAll(Arrays.asList(userIngredients));
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
recyclerListView.setHasFixedSize(false);
layoutManager = new LinearLayoutManager(this);
recyclerListView.setLayoutManager(layoutManager);
System.out.println("list.size() " + list.size());
adapter = new CustomAdapter(list,MainActivity.this);
adapter.setActionListener(this);
recyclerListView.setAdapter(adapter);
} catch (Exception e){
e.printStackTrace();
}
}
// callback listener for your items
#Override
public void onItemAction(View view, CustomAdapter.CustomActions customAction, int position) {
final String itemName = adapter.getItem(position);
System.out.println(customAction + ": You clicked " + itemName + " on row number " + position);
switch(itemName){
case "Whiskey":
if(customAction== CustomAdapter.CustomActions.CHECK){
Whiskey=true;
}
else{
Whiskey=false;
}
System.out.println("Whiskey set to: " + Whiskey);
break;
case "Bourbon":
if(customAction== CustomAdapter.CustomActions.CHECK){
Bourbon=true;
}
else{
Bourbon=false;
}
System.out.println("Bourbon set to: " + Bourbon);
break;
//case xyz
// and so on
default:
System.out.println("Not programmed yet: " + itemName);
}
}
}
As said above i removed the BaseAdapter and replaced it with the RecyclerView. We had to implement a custom ViewHolder-class that contains each row in our RecyclerViewList. Within the ViewHolder we can call the method on our listener whenever a checkbox-change event occurs.
CustomAdapter.java
import android.content.Context;
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.CompoundButton;
import android.widget.TextView;
import java.util.ArrayList;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.CustomViewHolder> {
//------ helper class for the viewholder
enum CustomActions{
CHECK,UNCHECK
}
// Provide a reference to the views for each row
public class CustomViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public CheckBox mCheckBox;
public CustomViewHolder(View v) {
super(v);
// the view element v is the whole linear layout element
CheckBox.OnCheckedChangeListener checkboxListenerForOneEntry = new CheckBox.OnCheckedChangeListener(){
#Override
public void onCheckedChanged(CompoundButton view, boolean isChecked) {
if (mItemActionListener != null) {
if(isChecked){
// this compoundbutton view element will be the checkbox
mItemActionListener.onItemAction(view, CustomActions.CHECK, getAdapterPosition());
}else{
mItemActionListener.onItemAction(view, CustomActions.UNCHECK, getAdapterPosition());
}
}
}
};
mTextView = v.findViewById(R.id.listviewtextlabel);
mCheckBox = v.findViewById(R.id.listviewcheckbox);
mCheckBox.setOnCheckedChangeListener(checkboxListenerForOneEntry);
}
}
//------
private ArrayList<String> list;
private Context context;
private LayoutInflater mInflater;
private ItemActionListener mItemActionListener;
public CustomAdapter(ArrayList<String> list, Context context) {
this.list = list;
this.context = context;
this.mInflater = LayoutInflater.from(this.context);
}
// allows clicks events to be caught
void setActionListener(ItemActionListener itemActionListener) {
this.mItemActionListener = itemActionListener;
}
// parent activity will implement this method to respond to click events
public interface ItemActionListener {
void onItemAction(View view, CustomActions customAction, int position);
}
// Create new views (invoked by the layout manager)
#Override
public CustomViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
// create a new view
View v = mInflater.inflate(R.layout.activity2_listview, parent, false);
return new CustomViewHolder(v);
}
// Replace the contents of a view (invoked by the layout manager)
#Override
public void onBindViewHolder(CustomViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.mTextView.setText(list.get(position));
}
#Override // Return the size of your dataset (invoked by the layout manager)
public int getItemCount() {
return getCount();
}
public int getCount() {
return list.size();
}
public String getItem(int pos) {
return list.get(pos);
}
}
Feel free to use the code as you like.
For more info about the RecyclerView see the google docs: https://developer.android.com/guide/topics/ui/layout/recyclerview

What's wrong with my implementation of RecyclerView?

I am following the Android Developer's explanatin on how to set RecyclerView, but I get some errors, for example android.widget.LinearLayout cannot be cast to android.widget.TextView.
The code taken from here : RecyclerView
This is my code, including all necessary files:
MainActivity.java:
package com.example.lastlocation.recyclerviewer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
mRecyclerView.setHasFixedSize(true);
// use a linear layout manager
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
String[] myDataset = new String[5];
myDataset[0] = "Data0";
myDataset[1] = "Data1";
myDataset[2] = "Data2";
myDataset[3] = "Data3";
myDataset[4] = "Data4";
// specify an adapter (see also next example)
mAdapter = new MyAdapter(myDataset);
mRecyclerView.setAdapter(mAdapter);
}
}
This is MyAdapter.java:
package com.example.lastlocation.recyclerviewer;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private String[] mDataset;
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public static class MyViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public MyViewHolder(TextView v) {
super(v);
mTextView = v;
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
// Create new views (invoked by the layout manager)
#Override
public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
TextView v = (TextView) LayoutInflater.from(parent.getContext())
.inflate(R.layout.my_text_view, parent, false);
MyViewHolder vh = new MyViewHolder(v);
return vh;
}
// Replace the contents of a view (invoked by the layout manager)
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.mTextView.setText(mDataset[position]);
}
// Return the size of your dataset (invoked by the layout manager)
#Override
public int getItemCount() {
return mDataset.length;
}
}
this is activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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=".MainActivity">
<View
android:id="#+id/view"
android:layout_width="386dp"
android:layout_height="135dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView"
android:layout_width="66dp"
android:layout_height="64dp"
android:layout_marginTop="24dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/view"
app:srcCompat="#android:color/holo_orange_dark" />
<TextView
android:id="#+id/textView2"
android:layout_width="68dp"
android:layout_height="30dp"
android:layout_marginTop="8dp"
android:text="John Doe"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView" />
<!-- A RecyclerView with some commonly used attributes -->
<android.support.v7.widget.RecyclerView
android:id="#+id/my_recycler_view"
android:layout_width="375dp"
android:layout_height="367dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="4dp"
android:scrollbars="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.428"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view"
app:layout_constraintVertical_bias="1.0" />
</android.support.constraint.ConstraintLayout>
And this is the xml for a single text view called my_text_view.xml:
<?xml version="1.0" encoding="utf-8"?>
<!-- Layout for a single list item -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp">
<TextView
android:id="#+id/my_text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
As you can see I nearly copied the code from the Android Developer's website, but I still don't know where is the problem.

public static class MyViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public MyViewHolder(TextView v) {
super(v);
mTextView = v;
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
The problem is in your ViewHolder constructor it should be like that
public static class MyViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public MyViewHolder(View v) {
super(v);
mTextView = v.findViewById(R.id.your_text_view_id);
}
}
#Override
public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View v = (TextView) LayoutInflater.from(parent.getContext())
.inflate(R.layout.my_text_view, parent, false);
MyViewHolder vh = new MyViewHolder(v);
return vh;
}
You are trying to assign LinearLayout which is the View in your constructor to your TextView and it is crashing. This will fix the problem.
The view you receive as a constructor param in your ViewHolder is the root view of your ViewHolder, in your case a LinearLayout, from this root view you can find the other views in it.

You are inflating row view wrongly and thus not assigning views in viewholder in proper manner change your code as below
#Override
public UserListAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
ViewHolder vh = new ViewHolder((inflater.inflate(R.layout.your_row_layout, parent, false)));
return vh;
}
and change your viewholder as below
public static class MyViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public MyViewHolder(View v) {
super(v);
mTextView = v.findViewById(R.id.my_text_view);
}
}

Just Simply you need to change your onCreateViewHolder method by taking as
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.my_text_view, parent, false);
return view;

LinearLayout within Recyclerview, within another LinearLayout within another RecyclerView

Good morning, I have a problem trying to link a Recyclerview with another Recyclerview, I mean one within others, the first recyclerview is in my activity, which in turn is filler for a second recyclerview, which is in a LinearLayout, since Once that recyclerview is filled by another layout that has an ImageView and a TextView, the problem is that I can not use the two recycler view since the app stops, but if I use the layout separately if they work in the same way, I know if I explain, I have 3 layouts which are:
The problem is that I can not use both recycler view since the app stops, but if I use the layout separately if they work in the same way, I do not know if I explain myself, I have 3 layouts, the one in the activity that contains a recyclerview, the container of the elements that contains the second recyclerview and a texview, and finally the layout portraitLayout that contains an imageView and a texView, if I only use the layout of the activity, the second one is rendered well but without any image, and if I remove the layout of the activity and leave the second with the third this is rendered with their respective images.
I have 2 adapters which are:
AdapterPortrait:
`public class Adapter_Portrait extends RecyclerView.Adapter<Adapter_Portrait.ViewHolder> {
private List<Portrait> portraits;
private int layout;
private OnItemClickListener listener;
private Context context;
public Adapter_Portrait(List<Portrait> portraits, int layout, OnItemClickListener listener) {
this.portraits = portraits;
this.layout = layout;
this.listener = listener;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v= LayoutInflater.from(parent.getContext()).inflate(this.layout,parent,false);
ViewHolder vh=new ViewHolder(v);
context=parent.getContext();
return vh;
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
holder.bind(portraits.get(position),this.listener);
}
#Override
public int getItemCount() {
return portraits.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
ImageView imageView;
TextView textView;
public ViewHolder(View itemView) {
super(itemView);
this.imageView = itemView.findViewById(R.id.imagePortrait);
this.textView = itemView.findViewById(R.id.textNamePortrait);
}
public void bind(final Portrait portrait, final OnItemClickListener listener){
this.textView.setText(portrait.getName_portrait());
Picasso.with(context).load(portrait.getImagePortrait()).fit().into(imageView);
itemView.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view) {
listener.onItemClick(portrait, getAdapterPosition());
}
});
}
}
public interface OnItemClickListener{
void onItemClick(Portrait portrait, int position);
}
}`
AdapterList_Pieces:
`public class AdapterList_Pieces extends
RecyclerView.Adapter<AdapterList_Pieces.ViewHolder> {
private List<Artist> artists;
private int layout;
private OnItemClickListener listener;
private Context context;
public AdapterList_Pieces(List<Artist> artists, int layout, OnItemClickListener listener) {
this.artists = artists;
this.layout = layout;
this.listener = listener;
}
public class ViewHolder extends RecyclerView.ViewHolder{
RecyclerView recyclerView;
TextView textView;
public ViewHolder(View itemView) {
super(itemView);
this.recyclerView = itemView.findViewById(R.id.RecyclerViewPieces);
this.textView = itemView.findViewById(R.id.textViewPieces);
}
public void bind(final Artist artist, final OnItemClickListener listener){
this.textView.setText(artist.getName_artist());
itemView.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view) {
listener.onItemClick(artist, getAdapterPosition());
}
});
}
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v= LayoutInflater.from(parent.getContext()).inflate(this.layout,parent,false);
ViewHolder vh=new ViewHolder(v);
context=parent.getContext();
return vh;
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
holder.bind(artists.get(position),this.listener);
}
#Override
public int getItemCount() {
return artists.size();
}
public interface OnItemClickListener{
void onItemClick(Artist artist, int position);
}
}`
My Activity is:
public class PiecesActivity extends AppCompatActivity {
List<Artist> artists;
List<Portrait> portraits;
RecyclerView recyclerView;
RecyclerView recyclerViewPiece;
RecyclerView.Adapter rAdapter;
RecyclerView.LayoutManager layoutManagerPiece;
RecyclerView.Adapter AdapterPiece;
RecyclerView.LayoutManager layoutManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.portraitcontenetorslayout);
recyclerView= findViewById(R.id.recyclerViewListPieces);
recyclerViewPiece= findViewById(R.id.RecyclerViewPieces);
artists= ConsultingInformation.getArtist();
portraits= ConsultingInformation.getPortrait();
layoutManager = new LinearLayoutManager(this);
layoutManagerPiece = new LinearLayoutManager(this);
rAdapter= new Adapter_Portrait(portraits,R.layout.portraitlayout, new Adapter_Portrait.OnItemClickListener(){
#Override
public void onItemClick(Portrait portrait, int position) {
Toast.makeText(PiecesActivity.this, "This piece is "+ portraits.get(position).getName_portrait(), Toast.LENGTH_LONG).show();
}
});
recyclerViewPiece.setHasFixedSize(true);
recyclerViewPiece.setItemAnimator(new DefaultItemAnimator());
recyclerViewPiece.setLayoutManager(layoutManagerPiece);
recyclerViewPiece.setAdapter(rAdapter);
AdapterPiece= new AdapterList_Pieces(artists,R.layout.portraitcontenetorslayout, new AdapterList_Pieces.OnItemClickListener(){
#Override
public void onItemClick(Artist artist, int positionArt) {
Toast.makeText(PiecesActivity.this, "This list of pieces is "+ artists.get(positionArt).getName_artist(), Toast.LENGTH_LONG).show();
}
});
recyclerView.setHasFixedSize(true);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(AdapterPiece);
}
}`
I had read that it was not possible to put a list downloadble within another, but i did not get an unstable method for my case that are two list of objects one within another.
My layouts just in case.
PortraitLayout:
<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content">
<ImageView
android:id="#+id/imagePortrait"
android:layout_width="78dp"
android:layout_height="63dp"
android:layout_marginLeft="25dp"
android:textAlignment="center"
android:contentDescription="TODO"
android:layout_marginStart="25dp" />
<TextView
android:id="#+id/textNamePortrait"
android:layout_width="225dp"
android:layout_height="30dp"
android:layout_marginLeft="10dp"
android:layout_marginTop="10dp"
android:text="TextView"
android:layout_marginStart="10dp" />
</LinearLayout>
portraitcontenetorlayout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical">
<TextView
android:id="#+id/textViewPieces"
android:layout_width="match_parent"
android:layout_height="35dp"
android:background="#BCBCBC"
android:paddingLeft="7dp"
android:text=" TextView"
android:gravity="center_vertical" />
<android.support.v7.widget.RecyclerView
android:id="#+id/RecyclerViewPieces"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
activitypieces:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical">
<TextView
android:id="#+id/textView3"
android:layout_width="match_parent"
android:gravity="center"
android:layout_height="30dp"
android:text="Obras" />
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerViewListPieces"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>

How do I use a RecyclerView

I am trying to add a RecyclerView to my app, but I am having lots of difficulties. I want the RecyclerView to have items of this layout
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/txtChords"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center_horizontal"
/>
<TextView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:id="#+id/txtLyrics"/>
</LinearLayout>
I put that into its own XML file, and declared the RecyclerView in the layout. But I don't know how to display the items
Thank you!!
I searched documentation and tutorials, but they all do something slightly different and too complicated when comparing to what I want to do. I just want to learn the basics of RecyclerViews and how to use them.
I will accept examples and any link
Please note that I am fairly new to android, and might need a simpler explanation

Recyclerview:
Recycler view is same as listview but recyclerview is added in android support lib for material design concept.
Example:
Add dependency for recyclerview
compile 'com.android.support:recyclerview-v7:23.1.0'
Add recyclerview in main layout file
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<android.support.v7.widget.RecyclerView
android:id="#+id/item_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
/>
</LinearLayout>
Make one item layout xml file (here is ur item file)
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/txtChords"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center_horizontal"
/>
<TextView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:id="#+id/txtLyrics"/>
</LinearLayout>
Make one model class for each item in list.it can be any custom class.
public class Item {
private String name;
public Item(String n) {
name = n;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Now most important part is to make adapter for recyclerview:
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.codexpedia.list.viewholder.R;
import java.util.ArrayList;
public class ItemArrayAdapter extends RecyclerView.Adapter<ItemArrayAdapter.ViewHolder> {
//All methods in this adapter are required for a bare minimum recyclerview adapter
private int listItemLayout;
private ArrayList<Item> itemList;
// Constructor of the class
public ItemArrayAdapter(int layoutId, ArrayList<Item> itemList) {
listItemLayout = layoutId;
this.itemList = itemList;
}
// get the size of the list
#Override
public int getItemCount() {
return itemList == null ? 0 : itemList.size();
}
// specify the row layout file and click for each row
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(listItemLayout, parent, false);
ViewHolder myViewHolder = new ViewHolder(view);
return myViewHolder;
}
// load data in each row element
#Override
public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
TextView item = holder.item;
item.setText(itemList.get(listPosition).getName());
}
// Static inner class to initialize the views of rows
static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView item;
public ViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
item = (TextView) itemView.findViewById(R.id.txtChords);
}
#Override
public void onClick(View view) {
Log.d("onclick", "onClick " + getLayoutPosition() + " " + item.getText());
}
}
This is simple adapter with minimum requirement method.
Now bind adapter with recyclerview
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import com.codexpedia.list.viewholder.R;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
RecyclerView recyclerView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initializing list view with the custom adapter
ArrayList <Item> itemList = new ArrayList<Item>();
ItemArrayAdapter itemArrayAdapter = new ItemArrayAdapter(R.layout.list_item, itemList);
recyclerView = (RecyclerView) findViewById(R.id.item_list);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(itemArrayAdapter);
// Populating list items
for(int i=0; i<100; i++) {
itemList.add(new Item("Item " + i));
}
}
}
Hope this example will help u...
You can ask any question if u have any confusion.
You can refer this link if u want to make complex list
https://www.binpress.com/tutorial/android-l-recyclerview-and-cardview-tutorial/156

How to create a Dynamic GridView

I create a Dynamic GridView with ArrayList Items and I want to create the Controls for shapes Some thing like this GridView GridView Example
and This Is my Code
This ArrayList
ArrayList<String> alphabets1;
alphabets1 = new ArrayList<String>();
alphabets1.add(rs.getString("Name"));
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, alphabets1);
and this is My Grid View
final GridView gridView = new GridView(this);
gridView.setVerticalSpacing(3);
gridView.setHorizontalSpacing(3);
gridView.setLayoutParams(new GridView.LayoutParams(WindowManager.LayoutParams.FILL_PARENT, WindowManager.LayoutParams.FILL_PARENT));
gridView.setNumColumns(4);
gridView.setAdapter(adapter);
gridView.setLayoutParams(linearLayoutParams);
this is my GridView enter image description here

GridView is used to display data in two dimension. In this tutorial we are going to show you how to implement custom GridView in Android with Images and Text.
Creating Layout:
The Main layout for our project is “activity_main” which has a GridView to display text with images.
activity_main.xml
<LinearLayout 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" >
<GridView
android:numColumns="auto_fit"
android:gravity="center"
android:columnWidth="100dp"
android:stretchMode="columnWidth"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/grid"
/>
</LinearLayout>
Next step is to create a layout for the grid item that is to be displayed in GridView. Create the layout as grid_single.xml which has a TextView to display the text which is stored in the Array and a ImageView to display set of images in each grid item.
grid_single.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="5dp" >
<ImageView
android:id="#+id/grid_image"
android:layout_width="50dp"
android:layout_height="50dp">
</ImageView>
<TextView
android:id="#+id/grid_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:textSize="9sp" >
</TextView>
</LinearLayout>
Creating Activity:
Before Creating the MainActivity we must create a CustomGrid class for our custom GridView which is extended to BaseAdapter.
CustomGrid.java
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class CustomGrid extends BaseAdapter{
private Context mContext;
private final String[] web;
private final int[] Imageid;
public CustomGrid(Context c,String[] web,int[] Imageid ) {
mContext = c;
this.Imageid = Imageid;
this.web = web;
}
#Override
public int getCount() {
// TODO Auto-generated method stub
return web.length;
}
#Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
#Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View grid;
LayoutInflater inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
grid = new View(mContext);
grid = inflater.inflate(R.layout.grid_single, null);
TextView textView = (TextView) grid.findViewById(R.id.grid_text);
ImageView imageView = (ImageView)grid.findViewById(R.id.grid_image);
textView.setText(web[position]);
imageView.setImageResource(Imageid[position]);
} else {
grid = (View) convertView;
}
return grid;
}
}
MainActivity.java
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;
public class MainActivity extends Activity {
GridView grid;
String[] web = {
"Google",
"Github",
"Instagram",
"Facebook",
"Flickr",
"Pinterest",
"Quora",
"Twitter",
"Vimeo",
"WordPress",
"Youtube",
"Stumbleupon",
"SoundCloud",
"Reddit",
"Blogger"
} ;
int[] imageId = {
R.drawable.image1,
R.drawable.image2,
R.drawable.image3,
R.drawable.image4,
R.drawable.image5,
R.drawable.image6,
R.drawable.image7,
R.drawable.image8,
R.drawable.image9,
R.drawable.image10,
R.drawable.image11,
R.drawable.image12,
R.drawable.image13,
R.drawable.image14,
R.drawable.image15
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
CustomGrid adapter = new CustomGrid(MainActivity.this, web, imageId);
grid=(GridView)findViewById(R.id.grid);
grid.setAdapter(adapter);
grid.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(MainActivity.this, "You Clicked at " +web[+ position], Toast.LENGTH_SHORT).show();
}
});
}
}
reference link https://www.learn2crack.com/2014/01/android-custom-gridview.html

same as we create listview just use gridView instead of list view in xml