Can't get RecyclerView to work [duplicate] - java

This question already has answers here:
Null pointer Exception - findViewById()
(12 answers)
Closed 4 years ago.
After being told to use a RecyclerView instead of a ListView, I have tried to implement it along with a SearchView. However, I get a strange error about an object being null:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
I currently have the following code:
SearchActivity.java
package com.rickteuthof.strangejourneycompendium;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.SearchView;
import java.util.ArrayList;
public class SearchActivity extends AppCompatActivity implements SearchView.OnQueryTextListener {
public static ArrayList<String> demonNames;
private SearchAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView r = findViewById(R.id.recyclerView);
demonNames = MainActivity.demonNames;
adapter = new SearchAdapter(this, demonNames);
r.setLayoutManager(new LinearLayoutManager(getApplicationContext(), LinearLayoutManager.VERTICAL, false));
r.setAdapter(adapter);
SearchView s = findViewById(R.id.searchBar);
s.setOnQueryTextListener(this);
}
#Override
public boolean onQueryTextSubmit(String query) {
return false;
}
#Override
public boolean onQueryTextChange(String newText) {
adapter.filter(newText);
return false;
}
}
SearchAdapter.java
package com.rickteuthof.strangejourneycompendium;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.Locale;
public class SearchAdapter extends RecyclerView.Adapter<SearchAdapter.MyViewHolder> {
private LayoutInflater inflater;
private ArrayList<String> demonNames;
private ArrayList<String> results;
public SearchAdapter(Context ctx, ArrayList<String> demonNames){
inflater = LayoutInflater.from(ctx);
this.demonNames = demonNames;
this.results = new ArrayList<String>();
this.results.addAll(SearchActivity.demonNames);
}
#NonNull
#Override
public SearchAdapter.MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.recycler_item, parent, false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull SearchAdapter.MyViewHolder holder, int position) {
holder.time.setText(demonNames.get(position));
}
#Override
public int getItemCount() {
return demonNames.size();
}
class MyViewHolder extends RecyclerView.ViewHolder{
TextView time;
public MyViewHolder(View itemView) {
super(itemView);
time = itemView.findViewById(R.id.result);
}
}
// Filter Class
public void filter(String charText) {
charText = charText.toLowerCase(Locale.getDefault());
SearchActivity.demonNames.clear();
if (charText.length() == 0) {
SearchActivity.demonNames.addAll(results);
} else {
for (String wp : results) {
if (wp.toLowerCase(Locale.getDefault()).contains(charText)) {
SearchActivity.demonNames.add(wp);
}
}
}
notifyDataSetChanged();
}
}
My dataset is a String array named demonNames which I try to filter to get the correct results in the RecyclerView.
Here are my xml layouts:
activity_search.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=".SearchActivity">
<SearchView
android:id="#+id/searchBar"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toTopOf="#+id/recyclerView"
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" />
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/searchBar" >
</android.support.v7.widget.RecyclerView>
</android.support.constraint.ConstraintLayout>
recycler_item.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">
<TextView
android:id="#+id/result"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

setContentView(R.layout.activity_main);
Replace this with
setContentView(R.layout.activity_search);

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i wanted to use intro slider to my App
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when I slide to any page the dots(. ) will be copy and increase
where is my problem and what should I do ?
package time.one.just.show.introslyder;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Html;
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public class MainActivity extends AppCompatActivity {
private ViewPager mSlideViewPager;
private LinearLayout mDotsLayout;
private SlyderAdapter slyderAdapter;
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private TextView[] mDots;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mSlideViewPager = findViewById(R.id.viewPager);
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mSlideViewPager.setAdapter(slyderAdapter);
addDotsIndiccator(0);
mSlideViewPager.addOnPageChangeListener(viewListener);
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private void addDotsIndiccator(int position) {
mDots = new TextView[3];
for (int i = 0; i < mDots.length; i++) {
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mDots[i].setText(Html.fromHtml("&#8226"));
mDots[i].setTextSize(35);
mDots[i].setTextColor(getResources().getColor(R.color.colorWhiteNearToGray));
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mDots[position].setTextColor(getResources().getColor(R.color.colorWite));
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}
ViewPager.OnPageChangeListener viewListener = new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int i, float v, int i1) {
}
#Override
public void onPageSelected(int i) {
addDotsIndiccator(i);
}
#Override
public void onPageScrollStateChanged(int i) {
}
};}
And this is my SideAdapter class
package time.one.just.show.introslyder;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v4.view.PagerAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
public class SlyderAdapter extends PagerAdapter {
Context context;
LayoutInflater layoutInflater;
public SlyderAdapter(Context context) {
this.context = context;
}
public int[] slide_imagesArray = {
R.drawable.eat,
R.drawable.men,
R.drawable.sleep};
public String[] slide_headerArray = {
"EAT", "men", "code"};
public String[] slide_descriptionArray = {
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};
#Override
public int getCount() {
return slide_headerArray.length;
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object o) {
return view == o;
}
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
View view = layoutInflater.inflate(R.layout.slide_layoout, container, false);
ImageView slideImageView = (ImageView) view.findViewById(R.id.slideImage);
TextView slideheader = (TextView) view.findViewById(R.id.slideheader);
TextView slidedescription = (TextView) view.findViewById(R.id.slideDescription);
slideImageView.setImageResource(slide_imagesArray[position]);
slideheader.setText(slide_headerArray[position]);
slidedescription.setText(slide_descriptionArray[position]);
container.addView(view);
return view;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
container.removeView((RelativeLayout) object);
}
}
and this is my SliderLayout
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">
<ImageView
android:id="#+id/slideImage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="89dp"
app:srcCompat="#drawable/eat" />
<TextView
android:id="#+id/slideheader"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="122dp"
android:layout_marginBottom="287dp"
android:text="بدون نیاز به اینترنت"
android:textSize="20sp"
android:textStyle="bold" />
<TextView
android:id="#+id/slideDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="0dp"
android:layout_marginBottom="171dp"
android:text="آرشیو کامل این خواننده محبوب همیشه در جیب شم ، ، هر کدام ز آهنگ ها را خواستید می توانید دانلود کنید و هر زمان دلتون خوست به آن ها گوش بدهید حتی بدون نیز به اینترنت" />
</RelativeLayout>
and activtymain xml
<?xml version="1.0" encoding="utf-8"?>
<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:background="#drawable/main_background"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.v4.view.ViewPager
android:id="#+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.view.ViewPager>
<LinearLayout
android:id="#+id/dots"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:orientation="horizontal"></LinearLayout>
</RelativeLayout>
I found a solution
just by add this inside my App
mDotsLayout.removeAllViews();
thank you all

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So I have this custom list adapter and listview thingy and I can't seem to get it to work. I've spent a couple of days now trying to figure how to fix it. Change this change that, nothing seems to work. Any idea? thanks
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import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
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import java.util.ArrayList;
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private static final String TAG = "MainActvty";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_inventory_actvity);
Log.d(TAG, "onCreate, Started");
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resClass wood = new resClass("Wood", 10);
resClass iron = new resClass("Iron", 50);
resClass meat = new resClass("Meat", 5);
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resArrayList.add(wood);
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public class resClass {
private String resType;
private int resCount;
public resClass(String resType, int resCount) {
this.resType = resType;
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this.resType = resType;
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return resCount;
}
public void setResCount(int resCount) {
this.resCount = resCount;
}
}
ResListAdapter.class
I'm guessing there is something wrong with the adapter. But I'm not really sure.
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.ArrayList;
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private static final String TAG = "ResListAdapter";
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int mResource;
public ResListAdapter( Context context, int resource, ArrayList<resClass> objects) {
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String resType = getItem(position).getResType();
int resCount = getItem(position).getResCount();
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The xml files
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
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android:textColor="#000"
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android:layout_width="wrap_content"
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It's been really frustrating guys hope I can find the solution by asking this time.

RecyclerView does not load data, shows nothing

I'm a beginner with Android and struggling with the implementation of a RecyclerView. Was working through a tutorial and changing the values to what I need. But when I start, the view stays empty. As far as I was planning, it was supposed to show 20 times the same item for the moment.
ExerciseList.java (Start Activity):
package com.example.erik.orlandoapp;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
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#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle(getString(R.string.title_activity_exercise_list));
setContentView(R.layout.activity_exercise_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
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}
ExerciseBlock.java:
package com.example.erik.orlandoapp;
import java.util.ArrayList;
import java.util.List;
public class ExerciseBlock {
private String title;
private int difficulty;
private int exerciseId;
private static int lastId = 0;
public ExerciseBlock(String title, int difficulty, int exerciseId) {
this.title = title;
this.difficulty = difficulty;
this.exerciseId = exerciseId;
}
public String getTitle() {
return title;
}
public int getDifficulty() {
return difficulty;
}
public int getExerciseId() {
return exerciseId;
}
public static ArrayList<ExerciseBlock> createContactsList(int numContacts) {
ArrayList<ExerciseBlock> exerciseBlocks = new ArrayList<ExerciseBlock>();
for (int i = 1; i <= numContacts; i++) {
exerciseBlocks.add(new ExerciseBlock("Title",1,1));
}
return exerciseBlocks;
}
}
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package com.example.erik.orlandoapp;
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.TextView;
import java.util.List;
public class ExerciseBlockAdapter extends RecyclerView.Adapter<ExerciseBlockAdapter.ViewHolder> {
private List<ExerciseBlock> exList;
private Context mContext;
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
View contactView = inflater.inflate(R.layout.exercise_item, parent, false);
ViewHolder viewHolder = new ViewHolder(contactView);
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#Override
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public int getItemCount() {
return exList.size();
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return this.txtExercise;
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public TextView getTxtDiff() {
return this.txtDiff;
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super(itemView);
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}
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package com.example.erik.orlandoapp;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import java.util.ArrayList;
public class UserListActivity extends AppCompatActivity {
ArrayList<ExerciseBlock> exerciseBlocks;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
RecyclerView rvContacts = (RecyclerView) findViewById(R.id.exerciseList);
exerciseBlocks = ExerciseBlock.createContactsList(20);
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rvContacts.setLayoutManager(new LinearLayoutManager(this));
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activity_exercise_list.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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"
android:fitsSystemWindows="true"
tools:context="com.example.erik.orlandoapp.ExerciseList">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="#dimen/appbar_padding_top"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/AppTheme.PopupOverlay">
</android.support.v7.widget.Toolbar>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/exerciseList"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_marginBottom="20dp"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
exercise_item.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"
android:paddingTop="10dp"
android:paddingBottom="10dp"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:weightSum="1">
<TextView
android:id="#+id/txtExName"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Whatever" />
<TextView
android:id="#+id/txtExDiff"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#color/colorDifEasy"
android:paddingBottom="6dp"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="6dp"
android:text="Leicht"
android:textSize="10sp" />
</LinearLayout>
Thanks a lot!
I don't see UserListActivity calling setContentView()
Either put this code inside ExersiceList Activity
RecyclerView rvContacts = (RecyclerView) findViewById(R.id.exerciseList);
exerciseBlocks = ExerciseBlock.createContactsList(20);
ExerciseBlockAdapter adapter = new ExerciseBlockAdapter(this, exerciseBlocks);
rvContacts.setAdapter(adapter);
rvContacts.setLayoutManager(new LinearLayoutManager(this));
or call setContentView(R.layout.activity_exercise_layout) on Your UserListActivity

Android Studio ListView items gravity

I want to have my items in listview looking like a conversation in messenger.
There is simple code of recieving messages:
if (arrayList2.get(y).toString().equals(myEmail)) {
arrayList.add(arrayList2.get(k).toString());
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When array.get.....equals(myEmail), the messages are from me so, they should stay like they are. When ...equals(recipientEmail), I want text to be on the right of the screen/or listview and have an background of image, like classically in messenger
I will recommend you to add all Your messages in one Arraylist and create two layouts one of sender with left gravity and one of receiver with right gravity then make a logic like-
if(arraylist.get(position).getUserID==currentUser){
senderLayout.setvisibility(View.VISIBLE);
senderTextview.setText(arraylist.get(position).getText)
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senderLayout.setvisibility(View.GONE);
receiverLayout.setvisibility(View.VISIBLE);
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Do this in getView method of your adapter.
You may create a row with 2 views. One on left and other on right. Based on your if condition you can make one of the views gone and the other visible. At any time only one view in that will be visible.
Another way of doing is to use single view in it and setting (left/right) gravity based on your condition.
You may refer http://www.uandblog.com/How-to-Create-Chat-Application-using-Firebase-in-Android-. See MainActivity.java and item.xml
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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
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android:layout_height="match_parent">
<com.github.library.bubbleview.BubbleTextVew
android:id="#+id/tv_chatRecive"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="7dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="35dp"
android:layout_marginTop="8dp"
android:padding="10dp"
android:textColor="#android:color/white"
android:visibility="gone"
app:angle="5dp"
app:arrowHeight="12dp"
app:arrowLocation="left"
app:arrowPosition="5dp"
app:arrowWidth="12dp"
app:bubbleColor="#color/colorPrimary" />
<com.github.library.bubbleview.BubbleTextVew
android:id="#+id/tv_chatSend"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_marginBottom="7dp"
android:layout_marginLeft="35dp"
android:layout_marginRight="10dp"
android:layout_marginTop="8dp"
android:padding="10dp"
android:textColor="#color/text_labelColoe"
android:visibility="gone"
app:angle="5dp"
app:arrowHeight="12dp"
app:arrowLocation="right"
app:arrowPosition="5dp"
app:arrowWidth="12dp"
app:bubbleColor="#android:color/white" />
</RelativeLayout>
and in Adapter class use this kind of logic to manage textview
#Override
public void onBindViewHolder(final CustomViewHolder customViewHolder, final int position) {
if (listChat.get(position).CHAT_SEND_RECIVE.equalsIgnoreCase("right")) {
customViewHolder.tvSend.setVisibility(View.VISIBLE);
customViewHolder.tvRecive.setVisibility(View.GONE);
customViewHolder.tvSend.setText(listChat.get(position).CHAT_MESSAGE);
} else if (listChat.get(position).CHAT_SEND_RECIVE.equalsIgnoreCase("left")) {
customViewHolder.tvRecive.setVisibility(View.VISIBLE);
customViewHolder.tvSend.setVisibility(View.GONE);
customViewHolder.tvRecive.setText(listChat.get(position).CHAT_MESSAGE);
}
}
Add key in chat responce like just i add right and left
Here is complete example.
Resources under drawable:
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"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.andrii.myapplication.MainActivity">
<android.support.v7.widget.RecyclerView
android:id="#+id/chat"
android:background="#color/colorAccent"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
Message layout will looks like so (message.xml):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<FrameLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="15dp"
android:paddingTop="10dp"
android:paddingBottom="10dp"
android:paddingRight="10dp"
android:background="#drawable/in_9">
<TextView
android:id="#+id/message"
android:textSize="18sp"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:breakStrategy="balanced"
android:maxWidth="200dp"
android:text="test"
/>
</FrameLayout>
</LinearLayout>
And finally in MainActivity.java :
package com.example.andrii.myapplication;
import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.LinkedList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
List<Message> list= new LinkedList<>();
list.add(new Message(true, "hi"));
list.add(new Message(false, "hello"));
list.add(new Message(true, "how are you"));
list.add(new Message(false, "I'm fine"));
list.add(new Message(false, "Test test test test test"));
RecyclerView view = (RecyclerView) findViewById(R.id.chat);
view.setLayoutManager(new LinearLayoutManager(this));
view.setAdapter(new ChatAdapter(this, list));
}
private class Message {
private boolean misMine;
private String mMessage;
public Message (boolean mine, String message) {
misMine = mine;
mMessage = message;
}
public boolean isMine() { return misMine; }
public String getMessage() { return mMessage; }
}
private class MessageViewHolder extends RecyclerView.ViewHolder {
private View mContainer;
private TextView mMessage;
public MessageViewHolder(View itemView) {
super(itemView);
mMessage = (TextView) itemView.findViewById(R.id.message);
mContainer = itemView.findViewById(R.id.container);
}
public void setMessage(String message) {
mMessage.setText(message);
}
public void setMine(boolean isMine) {
LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) mContainer.getLayoutParams();
params.gravity = isMine ? Gravity.RIGHT : Gravity.LEFT;
mContainer.setBackgroundResource(isMine ? R.drawable.out_9 : R.drawable.in_9 );
mContainer.setLayoutParams(params);
}
}
private class ChatAdapter extends RecyclerView.Adapter<MessageViewHolder> {
private List<Message> mMessages;
public ChatAdapter(Context context, List<Message> list) {
mMessages = list;
}
#Override
public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.message, parent, false);
MessageViewHolder holder = new MessageViewHolder(view);
return holder;
}
#Override
public void onBindViewHolder(MessageViewHolder holder, int position) {
Message message = mMessages.get(position);
holder.setMessage(message.getMessage());
holder.setMine(message.isMine());
}
#Override
public int getItemCount() {
return mMessages.size();
}
}
}
The result of code above:

StaggeredGrid RecyclerView not showing anything

I'm trying to inflate a RecyclerView which has as StaggeredGrid Layout, but it is not showing anything. I've pretty much copied previous code I've used before for the RecyclerView so I'm kind of stumped.
In MuseumStoriesViewHolder.onCreateViewHolder() the return of holder has the following value ViewHolder{337ec22b position=-1 id=-1, oldPos=-1, pLpos:-1 unboundundefined adapter position no parent} I'm not sure if this is realated, but it was something that seemed off to me.
It also might help to know that the fragment I'm inflating this RecyclerView is a nested Fragment.
Any help would be greatly appreciated.
MuseumFragment
package com.example.android.radiobuttontestproject.fragments;
import android.app.Activity;
import android.os.Bundle;
import android.app.Fragment;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.example.android.radiobuttontestproject.R;
import com.example.android.radiobuttontestproject.adapters.MuseumStoriesAdapter;
import com.example.android.radiobuttontestproject.helpers.pojo.StoryObject;
import com.example.android.radiobuttontestproject.test.SampleDataFactory;
import java.util.List;
import butterknife.Bind;
import butterknife.ButterKnife;
public class MuseumFragment extends Fragment {
private List<StoryObject> storyObjectList;
private StaggeredGridLayoutManager storyGridLayoutManager;
private MuseumStoriesAdapter storyAdapter;
#Bind(R.id.stories_recycler_view) RecyclerView storiesRecyclerView;
public static MuseumFragment newInstance() {
MuseumFragment fragment = new MuseumFragment();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
}
public MuseumFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_museum, container, false);
ButterKnife.bind(this, view);
//Sets up the stories
SampleDataFactory sampleDataFactory = new SampleDataFactory();
storyObjectList = sampleDataFactory.getSampleStories(
getResources().getStringArray(R.array.test_titles_for_grid_museum1),
getResources().getStringArray(R.array.test_desc_for_grid_museum1));
storyGridLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
storiesRecyclerView.setLayoutManager(storyGridLayoutManager);
storyAdapter = new MuseumStoriesAdapter(getActivity().getApplicationContext(), storyObjectList);
storiesRecyclerView.setAdapter(storyAdapter);
return view;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
#Override
public void onDetach() {
super.onDetach();
}
}
MuseumStoriesAdapter
package com.example.android.radiobuttontestproject.adapters;
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.TextView;
import android.widget.Toast;
import com.example.android.radiobuttontestproject.R;
import com.example.android.radiobuttontestproject.helpers.pojo.StoryObject;
import java.util.List;
public class MuseumStoriesAdapter extends RecyclerView.Adapter<MuseumStoriesAdapter.MuseumStoriesViewHolder> {
private List<StoryObject> itemList;
private LayoutInflater inflater;
private Context context;
public MuseumStoriesAdapter(Context context, List<StoryObject> itemList) {
this.itemList = itemList;
this.context = context;
inflater = LayoutInflater.from(this.context);
}
#Override
public MuseumStoriesViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
View view = inflater.inflate(R.layout.view_box_small, viewGroup, false);
MuseumStoriesViewHolder holder = new MuseumStoriesViewHolder(view);
return holder;
}
#Override
public void onBindViewHolder(MuseumStoriesViewHolder holder, int position) {
holder.title.setText(itemList.get(position).getTitle());
holder.desc.setText(itemList.get(position).getDescription());
}
#Override
public int getItemCount() {
return itemList.size();
}
class MuseumStoriesViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView type,title,desc;
public MuseumStoriesViewHolder(View itemView) {
super(itemView);
//Tried Butterknife, but it doesn't seem like it was working in the view holder. - Peter
type = (TextView) itemView.findViewById(R.id.small_box_type);
title = (TextView) itemView.findViewById(R.id.small_box_title);
desc = (TextView) itemView.findViewById(R.id.small_box_desc);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View view) {
Toast.makeText(view.getContext(), "Clicked Position = " + getPosition(), Toast.LENGTH_SHORT).show();
}
}
}
fragment_museum.xml
<ScrollView
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="com.example.android.radiobuttontestproject.fragments.MuseumFragment">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1">
<TextView
android:id="#+id/museum_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="#dimen/header_margin"
android:gravity="center"
android:textSize="#dimen/font_larger"
android:text="#string/museum_header" />
<android.support.v7.widget.RecyclerView
android:id="#+id/stories_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</ScrollView>
view_box_small.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="#dimen/small_box_margin"
android:background="#color/small_box_background_color">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<!--TODO Make layout_height wrap contenet -->
<ImageView
android:layout_width="match_parent"
android:layout_height="120dp"
android:background="#color/test_color2"/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:src="#drawable/abc_btn_rating_star_off_mtrl_alpha"
/>
</FrameLayout>
<TextView
android:id="#+id/small_box_type"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="#dimen/font_small"
android:textColor="#color/font_red"
android:text="Object"
/>
<TextView
android:id="#+id/small_box_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="#dimen/font_large"
android:textColor="#color/font_black"
android:text="Sample Text Here"
/>
<TextView
android:id="#+id/small_box_desc"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="#dimen/font_normal"
android:textColor="#color/font_black"
android:textStyle="italic"
android:text="Sample Text Here"
/>
</LinearLayout>

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