OnClicklistener in RecyclerView [duplicate] - android-studio

Thank you in advance and dont be very hard with me, it is my first question.
I was trying to add a new item to my recyclerView through the adapter by declaring a method in my adapter called addItem(String newItem)
Then I tried to call this method when the floating button is clikced and the problem is that the method does not even appear when i hit cntrl+space and if i write it down it gets on red.
I have already tried to rebuild the project and nothing changes.
¿Any ideas about how to solve it?
MainActivity class
package com.example.sakur.recyclerviewapp;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
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 android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private FloatingActionButton mFloatingActionButton;
private List<String> recyclerItems = Collections.emptyList();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
recyclerItems = new ArrayList<>();
recyclerItems.add("First item");
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new MyAdapter(recyclerItems);
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.floating_action_button);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String itemNuevo = "New Card";
mAdapter.addItem(itemNuevo);
Snackbar.make(view, "Item added successfully", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
and the MyAdapter class
package com.example.sakur.recyclerviewapp;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.Collections;
import java.util.List;
/**
* Created by Sakur on 19/12/2015.
*/
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private List<String> mDataset= Collections.emptyList();
// 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
// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter(List<String> myDataset) {
mDataset = myDataset;
}
public void addItem(String newItem){
mDataset.add(newItem);
notifyDataSetChanged();
}
// Create new views (invoked by the layout manager)
#Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
// create a new view
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_card, parent, false);
// set the view's size, margins, paddings and layout parameters
//...
ViewHolder vh = new ViewHolder(v);
return vh;
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.mTextView.setText(mDataset.get(position));
}
// Return the size of your dataset (invoked by the layout manager)
#Override
public int getItemCount() {
return mDataset.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public ImageView mImageView;
public ViewHolder(View v) {
super(v);
mTextView = (TextView) v.findViewById(R.id.text_card);
}
}
}

addItem(String) is not a method of RecyclerView.Adapter, but of your MyAdapter subclass. Obviously, RecyclerView.Adapter has no knowledge of the existence neither of your MyAdapter nor of your addItem(String).
you can either change
private RecyclerView.Adapter mAdapter;
into
private MyAdapter mAdapter;
or cast mAdapter. E.g.
if (mAdater instanceof MyAdapter) {
((MyAdapter) mAdapter).addItem(...);
}

Related

new View.OnClickListener () greyed out ->" No Adapter Attached, skipping Layout" error message

I copied code for a recycler View from a Youtube tutorial but it won't work out for me. The new View.OnClickListener() is greyed out, with Android Studio suggesting to replace out with lambda. This is the only difference from my code to the one from the tutorial... The App runs through, but doesn't show the Layout, as I get the error message E/RecyclerView: No adapter attached; skipping layout.
what can I do to fix this?
This is the Adapter class:
package com.example.yourfoodweek;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.cardview.widget.CardView;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
public class MealsRecViewAdapter extends RecyclerView.Adapter<MealsRecViewAdapter.ViewHolder>{
private static final String TAG = "MealsRecViewAdapter";
private ArrayList <Food> meals = new ArrayList<>();
private Context mContext;
public MealsRecViewAdapter(Context mContext) {
this.mContext = mContext;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_meals_list, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
Log.d(TAG, "onBindViewHolder: Called");
holder.txtName.setText(meals.get(position).getName());
Glide.with(mContext)
.asBitmap()
.load(meals.get(position).getImageUrl())
.into(holder.imgFood);
holder.parent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v){
Toast.makeText(mContext, meals.get(position).getName() + "Selected", Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return meals.size();
}
public void setMeals(ArrayList<Food> meals) {
this.meals = meals;
notifyDataSetChanged();
}
public class ViewHolder extends RecyclerView.ViewHolder{
private CardView parent;
private ImageView imgFood;
private TextView txtName;
public ViewHolder(#NonNull View itemView){
super(itemView);
parent = itemView.findViewById(R.id.parent);
txtName = itemView.findViewById(R.id.txtMealName);
imgFood = itemView.findViewById(R.id.imgFood);
}
}
}
both problems are totally different. first one was suggestion means if you don't want to apply you can skip it. but i will not suggest to do that.
for example:
(without Lambda)
myButton.setOnClickListener(new View.OnClickListerner(){
#Override
void onClick(View v) {
// do some stuff related to action
}
});
(with Lambda)
myButton.setOnClickListener(v -> {
// do some stuff related to action
})
for other question
no layout manager attached:
if your RecyclerView doesn't have any LayoutManager attached to it then it will skip cause it will not know how to arrange/show items.
Some LayoutManagers:
LinearLayoutManager
GridLayoutManager
StaggeredGridLayoutManager
if you want to create your own LayoutManager you can do it by just extending class LayoutManager
how to use it:
....
LinearLayoutManager layoutManager = new LinearLayoutManager();
layoutManager.setOrientation = LinearLayoutManager.HORIZONTAL
myRecyclerViewObj.setLayoutManager(layoutManager);
....
no adapter attached
similar to no layout manager this will be shown when no adapter attached to recycler view for this you have to use setAdapter method to set your adapater
for example:
....
MealsRecViewAdapter adapter = new MealsRecViewAdapter(this);
myRecyclerViewObj.setAdapter(adapter);
....

How to use 2 public classes, protected void on creat functions in the same fragments?

How to put more than one class,overview,void in MainActivity java of Android Studio? I need to have both the button and a code to make the map of google have some restricions in the same page. What names of the classes should be changed for it to work. The codes work when put independently but not together.How to make them work good together?
package com.example.maps;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.LatLngBounds;
import com.google.android.gms.maps.model.MarkerOptions;
public class FirstFragment extends AppCompatActivity {
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
openFoodFragment();
}
});
}
public void openFoodFragment(){
Intent intent = new Intent(this, FoodFragment.class);
startActivity(intent);
}
}
public class MainACTIVITY extends FragmentActivity implements OnMapReadyCallback {
GoogleMap mapAPI;
SupportMapFragment mapFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mapFragment =(SupportMapFragment)
getSupportFragmentManager().findFragmentById(R.id.mapAPI);
mapFragment.getMapAsync(this);
}
public void openFoodFragment(){
Intent intent = new Intent(this, FoodFragment.class);
startActivity(intent);
}
#Override
public void onMapReady(GoogleMap googleMap){
mapAPI = googleMap ;
LatLng one = new LatLng(-21.754812, -48.219451);
LatLng two = new LatLng(-21.787443, -48.113332);
LatLngBounds.Builder builder = new LatLngBounds.Builder();
//add them to builder
builder.include(one);
builder.include(two);
LatLngBounds bounds = builder.build();
//get width and height to current display screen
int width = getResources().getDisplayMetrics().widthPixels;
int height = getResources().getDisplayMetrics().heightPixels;
int padding = (int) (width * 0.20);
mapAPI.setLatLngBoundsForCameraTarget(bounds);
mapAPI.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, width, height, padding));
//set zoom to level to current so that you won't be able to zoom out viz. move outside bounds
mapAPI.setMinZoomPreference(mapAPI.getCameraPosition().zoom);
LatLng Kampai = new LatLng(-21.780985, -48.186859);
mapAPI.addMarker(new MarkerOptions().position(Kampai).title("Kampai"));
mapAPI.moveCamera(CameraUpdateFactory.newLatLng(Kampai));
}
}
Yes the can be in the same file but you have your mainACTIVITY inside your FirstFragment which cannot happen you need to remove the bottom most bracket and place it right above the start of your mainACTIVITY class, your FirstFragment's brackets need to close before you paste another class into the file.

Cannot update TextView from another class

My android project has 3 class MainActivity.java , itemlist.java and Bill.java
I created the object of Bill class from itemlist.java class and passed context from there.
So when i try to update textview from Bill.java class it simply does not update but when i do same from MainActivity it works
So my question is how to make this TextView update work?
package com.example.smit.databasedemo.Functions;
import android.app.Activity;
import android.content.Context;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.TextView;
import com.example.smit.databasedemo.MainActivity;
import com.example.smit.databasedemo.R;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Created by Smit on 18-02-2020.
*/
public class Bill extends AppCompatActivity{
private LayoutInflater inflater;
private final View view;
public Bill(Context context){
inflater = (LayoutInflater) context.getSystemService(LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.activity_main,null);
}
Here context is passed by using getApplicationContext() passed from MainActivity
public void calculate(String bill){
final TextView billText = (TextView) view.findViewById(R.id.useless);
String text = (billText.getText().toString())+bill;
//Here the text is fetched from same textbox but fail's to update
Pattern p = Pattern.compile("\\d+");
Matcher m = p.matcher(text);
String[] amount= new String[2];
int i=0;
while(m.find()){
amount[i] = m.group();
i++;
}
int amount_prev = Integer.valueOf(amount[0]);
final int total = (amount_prev)+(Integer.valueOf(amount[1]));
billText.setText("Total Bill:"+total+"Rs");
//Cannot update this textbox
}
}
final Bill bill = new Bill(context);
//this is how its called
public void onClick(View v) {
counter++;
price= (finalViewHolder.price.getText().toString());
finalViewHolder.item.setText(String.valueOf(counter));
bill.calculate(price);
}
p.s tried running on uiThread() does not work
You have to pass the Context reference via constructor:
public Bill(Context context){
this.context=context;
//rest of your code...
}
Also find the TextView like this:
TextView billText = (TextView) ((Activity)context).findViewById(R.id.useless);

Pass different data : ViewPager cards inspired by Duolingo

I just started app developing recently and stumbled upon a problem that I basically can't figure out : https://rubensousa.github.io/2016/08/viewpagercards
He instructed that on CardPagerAdapter.java in instantiateItem, I need to set the data according to the position. But how do I do it?
I want the first card to have a title of "FIRST CARD" while the second "SECOND CARD" and so on.. hope someone could help.
CardPagerAdapter.java
import android.support.v4.view.PagerAdapter;
import android.support.v7.widget.CardView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class CardPagerAdapter extends PagerAdapter implements CardAdapter {
private List<CardView> mViews;
private List<CardItem> mData;
private float mBaseElevation;
public CardPagerAdapter() {
mData = new ArrayList<>();
mViews = new ArrayList<>();
}
public void addCardItem(CardItem item) {
mViews.add(null);
mData.add(item);
}
public float getBaseElevation() {
return mBaseElevation;
}
#Override
public CardView getCardViewAt(int position) {
return mViews.get(position);
}
#Override
public int getCount() {
return mData.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
View view = LayoutInflater.from(container.getContext())
.inflate(R.layout.fragment_adapter, container, false);
container.addView(view);
bind(mData.get(position), view);
CardView cardView = (CardView) view.findViewById(R.id.cardView);
if (mBaseElevation == 0) {
mBaseElevation = cardView.getCardElevation();
}
cardView.setMaxCardElevation(mBaseElevation * MAX_ELEVATION_FACTOR);
mViews.set(position, cardView);
return view;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
mViews.set(position, null);
}
private void bind(CardItem item, View view) {
TextView title = (TextView) view.findViewById(R.id.title);
TextView description = (TextView) view.findViewById(R.id.description);
Button button = (Button) view.findViewById(R.id.button);
title.setText(item.getTitle());
description.setText(item.getText());
button.setText(item.getButton());
}
}

cannot find symbol variable Android Studio 0.8.1

I am new to android studio and I am trying to run this code.
My code:
package app.sunshine.android.example.com.sunshine;
import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MyActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
if (savedInstanceState == null) {
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.my, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_my, container, false);
// Create some dummy data for the ListView. Here's a sample weekly
// Represented as "day, whether, high/low"
String[] forecastArray= {
"Today - Sunny - 88/63",
"Tomorrow - Foggy - 70/40",
"Weds - Cloudy - 72/63",
"Thurs - Asteroids - 75/65",
"Fri - Heavy Rain - 65/56",
"Sat - HELP TRAPPED IN WEATHERSTATION - 60/51",
"Sun - Sunny - 80/68"
};
List<String> weekForecast = new ArrayList<String>(
Arrays.asList(forecastArray));
// Now that we have some dummy forecast data, create an ArrayAdapter.
// The ArrayAdapter will take data from a source ( Like our dummy forecast
// use to populate the ListView it's attached to
mforecastAdapter =
new ArrayAdapter<String>(
//The current context( this fragment's parent activity
getActivity(),
// ID of list item layout
R.layout.list_item_forecast,
// ID of the textview to populate
R.id.list_item_forecast_textview,
// Forecast data
weekForecast);
// Get a reference to the LIstView and attach this adpater to it
ListView listView = (ListView) rootView.findViewById(
R.id.listview_forecast);
listView.setAdapter(mForecastAdapter);
return rootView;
}
}
}
but I get the following error : cannot find symbol variable
I tried cleaning the project gradle and restarted android application .
but I am still encountering the issue
any help would be greatly appreciated :)
I am following this tutorial https://www.udacity.com/course/viewer#!/c-ud853/l-1395568821/e-1395668601/m-1395668603
You need to declare mForecastAdapter.
public static class PlaceholderFragment extends Fragment {
ArrayAdapter<String> mForecastAdapter;
public PlaceholderFragment() {
}
Since you have not done that yet it does not recognize the variable mForecastAdapter. Hope this helps.

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